Re: [time-nuts] I love the smell of tantalum in the morning

[Clint Jay]

Definitely, for a proven bad or dirt cheap leaded part when the board is
valuable cut the legs. gives you an added advantage when removing the part
as well as you can apply heat to both sides of the leg if it's through
hole.

On 5 November 2016 at 21:56, Mark Sims  wrote:

> Tom's method is what I use when replacing commodity parts that I don't
> care about salvaging.  Much less chance of damaging anything.   Hack the
> part apart,  cut the leads on gull wing packages, etc.  Don't waste your
> time with tweezers,  lifting one end, etc.   I have a very nice set of hot
> tweezers and almost never use them.
>
> And for DIP packages cut the package free from the leads first...  even
> though I have a $6000+ vacuum desoldering station,  trying to get all the
> leads unsoldered cleanly and prying out the chip always risks tearing out a
> feed through... particularly on multi-layer boards with out thermal
> isolation vias on power/ground connections.
>
> -
>
> >  I usually nibble away at the center of the part until it is two separate
> pieces. Then unsolder each piece. Clean the pads off with wick then install
> the new part.
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-- 
Clint.

*No trees were harmed in the sending of this mail. However, a large number
of electrons were greatly inconvenienced.*
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Re: [time-nuts] I love the smell of tantalum in the morning

[Everett B. Fulton]

I also use the double-iron method over hot air for tiny components. I use them 
like tweezers, yet with an improvement in dexterity.

Liberal use of liquid or paste flux, in addition to what might be in the solder 
itself, is very helpful in obtaining good results.  If you have the "SMT 
solder paste" with tiny spheres of solder mixed in with rosin paste, that also 
works well.

Obviously, a hot air machine with assortment of nozzles is the easiest way to 
handle components with a large lead count.  Under "field conditions" I've 
actually used a common heat gun and a watchful eye on the phase change.  Since 
leaving the 2-way radio field a dozen years ago, I only get to work on my own 
gear.  I still like maintaining the ability, although the eyesight is becoming 
an issue.  Time for those glasses I've been avoiding...

First post for me, despite a few years of lurking.  Always one of my favorite 
reads!

On Saturday, November 05, 2016 12:55:55 PM Hal Murray wrote:
> t...@leapsecond.com said:
> > Having not done SMT before, how should I do it with minimal risk to the
> > very precious PCB. Or, what equipment should I use this as a good excuse
> > to buy?
> 
> If you can get at it, 2 soldering irons, one on each end, works reasonably
> well.  When both ends are melted, just push the part out of the way.
> Small/light things like 0805 resistors will frequently stick to one of the
> tops by surface tension of the liquid solder.

-- 
Everett B. Fulton, AF5OK
eful...@rackspace.com
DNS/NTP Engineer
(the other time-nuts guy from the Spring Branch TX area)
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Re: [time-nuts] I love the smell of tantalum in the morning

[Bill Hawkins]

So what are the odds that the failed cap would be C13?

Is this cause for triskaidekaphobia?  ;-)

Please pardon this random excursion outside the bounds of precision
time.

Bill Hawkins

(who learned not to let kakorraphiophobia lead me to osphresiolagnia
[bad odors, not erotic] in college)

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Re: [time-nuts] I love the smell of tantalum in the morning

[David]

I usually find that the pad itself has enough tin plating to melt and
adhere the part's termination so I tack it down like that, solder the
second termination, and then go back and solder the first termination.

On Mon, 7 Nov 2016 02:34:51 +, you wrote:

>The best way to hand solder small SMT parts is to put a blob of solder on one 
>pad,  position the part,  old it down with something (fingernail works well, 
>maybe tweezers),  then touch that pad/solder blob with the iron.  The blob 
>should melt and the part should push down into the blob.  Make sure the part 
>is aligned, then go to town soldering the remaining pads. Go back and touch up 
>the blob pad.
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Re: [time-nuts] I love the smell of tantalum in the morning

[Tom Van Baak]

Thank you everyone for the superb set of replies to this posting over the 
weekend. I'm sure I will have my 5071A boards working again shortly. Thanks 
also for the generous offers on- and off-list from people who do this 
professionally. The level of hands-on experience on this list is amazing.

If there's more to add to the thread in the coming week, perhaps send it to me 
off-list.

Thanks,
/tvb

- Original Message - 
From: "Tom Van Baak" 
To: "Discussion of precise time and frequency measurement" 
Sent: Saturday, November 05, 2016 11:12 AM
Subject: [time-nuts] I love the smell of tantalum in the morning


See C13 in the attached photo. I need to replace some blown caps on a few 
boards [1]. In one instance the cap got so hot it melted itself off the board. 
Quiet convenient, actually -- it acts like its own fuse -- but I don't think 
the 5071 designers had that clever feature in mind.

Having not done SMT before, how should I do it with minimal risk to the very 
precious PCB. Or, what equipment should I use this as a good excuse to buy?

Thanks,
/tvb

[0] http://www.imdb.com/title/tt0078788/quotes
[1] http://leapsecond.com/museum/hp5071a/A1-mother.htm

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Re: [time-nuts] I love the smell of tantalum in the morning

[Christopher Hoover]

+1

I only use tweezers for removal.  I use the one-side-then-the-other
technique described elsewhere in this thread for mounting parts.
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[time-nuts] I love the smell of tantalum in the morning

[Mark Sims]

The best way to hand solder small SMT parts is to put a blob of solder on one 
pad,  position the part,  old it down with something (fingernail works well, 
maybe tweezers),  then touch that pad/solder blob with the iron.  The blob 
should melt and the part should push down into the blob.  Make sure the part is 
aligned, then go to town soldering the remaining pads. Go back and touch up the 
blob pad.
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Re: [time-nuts] I love the smell of tantalum in the morning

[Nathan Johnson]

I run two Hakko 936 stations with 907 irons. I use the wide chisel tips, 
and just heat both sides at once. The two Hakko stations are cheaper than a 
set of Metcal tweezera(although I would love a set of those)

Nathan KK4REY

via Newton Mail 
[https://cloudmagic.com/k/d/mailapp?ct=pi=9.2.5=10.1=email_footer_2]

On Sun, Nov 6, 2016 at 14:42, Bryan _  wrote:
If the SMD is small enough I have found it easy to remove by just applying 
a blob of solder to one end, this will quickly gap over to the other lead, 
and the SMD component and solder ball just slides off the board. Only works 
on the very small components though.



-=Bryan=-



From: time-nuts  on behalf of Robert 
LaJeunesse 

Sent: November 6, 2016 8:42 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] I love the smell of tantalum in the morning

Another admittedly low-budget way of heating both ends is to use a heat 
spreader. Solder a short piece of braid to one component end, fold it over 
the top of the part, and solder it to the other end. Heat the braid in the 
center, add solder until both ends are melted, and lift the combination off 
with tweezers. Sometimes a heavy enough copper wire bent around the part 
will also work as the heat spreader..


Bob LaJeunesse

> Sent: Saturday, November 05, 2016 at 9:05 PM
> From: "Andy ZL3AG via time-nuts" 
> To: "Discussion of precise time and frequency measurement" 


> Subject: Re: [time-nuts] I love the smell of tantalum in the morning
>
>
> Yes. Unless you're grinding it away with a dremel (which I wouldn't 
recommend as far as chemical dust is concerned), nibbling away with 
sidecutters would be trying to force the 2 ends of the component apart. 
That may be stressing the pads they're soldered to, leading to a possible 
pad lifting at some stage.

>
> Any of the methods mentioned that heat both ends at the same time - 
allowing the component to be wiped off the board - would have to be the 
best, stress-wise.

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Re: [time-nuts] I love the smell of tantalum in the morning

[jimlux]

On 11/6/16 4:17 PM, Hal Murray wrote:


jim...@earthlink.net said:

tweezers to remove
single iron to install
use a orange stick to hold the part down while you solder each end.


How many hands does that take?

I normally use one to hold the iron and the other to apply solder.



You can hold the stick in one hand with a couple of fingers and use your 
thumb and forefinger for the solder.


And, there's always your teeth

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Re: [time-nuts] I love the smell of tantalum in the morning

[Robert LaJeunesse]

I tear off a short piece of solder and push it up against the part (with 
orangewood stick) before picking up the iron.

Bob LaJeunesse



> Sent: Sunday, November 06, 2016 at 7:17 PM
> From: "Hal Murray" 
> To: "Discussion of precise time and frequency measurement" 
> 
> Cc: hmur...@megapathdsl.net
> Subject: Re: [time-nuts] I love the smell of tantalum in the morning
>
> 
> jim...@earthlink.net said:
> > tweezers to remove
> > single iron to install
> > use a orange stick to hold the part down while you solder each end. 
> 
> How many hands does that take?
> 
> I normally use one to hold the iron and the other to apply solder.
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] I love the smell of tantalum in the morning

[Hal Murray]

jim...@earthlink.net said:
> tweezers to remove
> single iron to install
> use a orange stick to hold the part down while you solder each end. 

How many hands does that take?

I normally use one to hold the iron and the other to apply solder.

-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] I love the smell of tantalum in the morning

[Gerhard Hoffmann]

Am 06.11.2016 um 22:16 schrieb Bryan _:

By far the easiest method.


https://youtu.be/3jxSKaIRhAQ

That must be the guy who removes the e**y MV-89s from China from their 
boards.

At least two of mine have scars that are best explained by such a tool.

regards, Gerhard
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Re: [time-nuts] I love the smell of tantalum in the morning

[jimlux]

On 11/6/16 10:47 AM, Adrian Godwin wrote:

You might also want normal cold tweezers to place the part. I'm not sure
what an orange stick is, around here I'd use a wooden toothpick. Perhaps
that's the same thing !


An orange stick is a piece of wood about 1/4" in diameter which has been 
tapered and then trimmed to a chisel point. I don't know if they were 
originally colored orange, or they're made from the wood of orange trees 
or what.


A quick google says they're also used for nail art and cuticle pushing, 
and are made from orangewood.  I note that orangewood doesn't 
necessarily mean "wood from orange trees", which I can't imagine being a 
good lumber to process (small diameter, not straight, etc.).


I would guess that they're made from fir or birch or something which 
comes in logs and has straight grain - essentially a giant toothpick.


Any way, they are non-magnetic, non conductive (but not an insulator, so 
they're ESD safe), a thermal insulator (so the heat on your part isn't 
sucked into the tool).


They're also great for pushing a SMD part off the pads gently when the 
solder has been liquified.


And for holding copper foil snowflakes when tuning a microwave circuit




The Swiss Venus tweezers have a lovely finish and the ends always meet.
There are probably others as good.

If you get some placing tweezers, make sure they're antimagnetic. Some
small parts (even resistors, that I wouldn't expect to contain steel) seem
to stick even to stainless steel. I've also heard bambooo tweezers are
good, but have never tried them.


On Sun, Nov 6, 2016 at 6:17 PM, jimlux  wrote:


On 11/6/16 9:24 AM, Scott Stobbe wrote:


I would not recommend purchasing soldering tweezers without trying them
first. They are not easy to control solder application when mounting a
component.



tweezers to remove
single iron to install
use a orange stick to hold the part down while you solder each end.







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Re: [time-nuts] I love the smell of tantalum in the morning

[Graham / KE9H]

If you are in a position where you are worried about damaging the PCB.
(And I would really be worried cutting any part in half with cutters, or
cutting leads off an IC with diagonal cutters.)
For two leaded parts, "Hot tweezers" work fine.
For parts with more leads, like ICs, you need hot air tools.

If you don't have those tools, or you have an unusually expensive or rare
PCB, consider low temperature solder.

You can buy a kit (from Mouser or others) for $16 called "ChipQuik" SMD1

Watch the video:
http://www.chipquik.com/store/product_info.php?products_id=210001

Manufacturer's Part number SMD1
Mouser part number: 910-SMD1

Remove as much normal (lead containing or lead-free) solder as you can from
each lead with solder wick.
Flood each pin with the low temp solder alloy (melting temp about 136
degrees F or 58 degrees C)
Usually putting a soldering iron on any one pin (or use a hot air pencil)
will raise the entire part and nearby board above 136 degrees F, so just
pick the part off with tweezers.
Now clean off all the low temp solder with solder-wick or as instructed.

For $16, you get enough for several years of casual reworks.
This is much gentler on the PC board than any other technique.

--- Graham

==

On Sun, Nov 6, 2016 at 2:42 PM, Bryan _  wrote:

> If the SMD is small enough I have found it easy to remove by just applying
> a blob of solder to one end, this will quickly gap over to the other lead,
> and the SMD component and solder ball just slides off the board. Only works
> on the very small components though.
>
>
> -=Bryan=-
>
>
> 
> From: time-nuts  on behalf of Robert
> LaJeunesse 
> Sent: November 6, 2016 8:42 AM
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] I love the smell of tantalum in the morning
>
> Another admittedly low-budget way of heating both ends is to use a heat
> spreader. Solder a short piece of braid to one component end, fold it over
> the top of the part, and solder it to the other end. Heat the braid in the
> center, add solder until both ends are melted, and lift the combination off
> with tweezers. Sometimes a heavy enough copper wire bent around the part
> will also work as the heat spreader..
>
> Bob LaJeunesse
>
> > Sent: Saturday, November 05, 2016 at 9:05 PM
> > From: "Andy ZL3AG via time-nuts" 
> > To: "Discussion of precise time and frequency measurement" <
> time-nuts@febo.com>
> > Subject: Re: [time-nuts] I love the smell of tantalum in the morning
> >
> >
> > Yes. Unless you're grinding it away with a dremel (which I wouldn't
> recommend as far as chemical dust is concerned), nibbling away with
> sidecutters would be trying to force the 2 ends of the component apart.
> That may be stressing the pads they're soldered to, leading to a possible
> pad lifting at some stage.
> >
> > Any of the methods mentioned that heat both ends at the same time -
> allowing the component to be wiped off the board - would have to be the
> best, stress-wise.
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> time and frequency measurement and related topics. To see the collection of
> prior postings to ...
>
>
>
> and follow the instructions there.
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Re: [time-nuts] I love the smell of tantalum in the morning

[Bryan _]

By far the easiest method.


https://youtu.be/3jxSKaIRhAQ



-=Bryan=-



From: time-nuts  on behalf of Scott Stobbe 

Sent: November 6, 2016 1:10 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] I love the smell of tantalum in the morning

In the case of the rt7 (or knife soldering tips for other brands) you get a
fine point that easily handles 30-32 awg wire, and the edge of the tip is a
little over 100 thou long, so for parts 0805 and smaller you just lay the
edge along the side of the component and heat both pads and swipe it to the
side.

On Sunday, 6 November 2016, Bryan _  wrote:

> If the SMD is small enough I have found it easy to remove by just applying
> a blob of solder to one end, this will quickly gap over to the other lead,
> and the SMD component and solder ball just slides off the board. Only works
> on the very small components though.
>
>
> -=Bryan=-
>
>
> 
> From: time-nuts > on behalf of
> Robert LaJeunesse >
> Sent: November 6, 2016 8:42 AM
> To: time-nuts@febo.com 
> Subject: Re: [time-nuts] I love the smell of tantalum in the morning
>
> Another admittedly low-budget way of heating both ends is to use a heat
> spreader. Solder a short piece of braid to one component end, fold it over
> the top of the part, and solder it to the other end. Heat the braid in the
> center, add solder until both ends are melted, and lift the combination off
> with tweezers. Sometimes a heavy enough copper wire bent around the part
> will also work as the heat spreader..
>
> Bob LaJeunesse
>
> > Sent: Saturday, November 05, 2016 at 9:05 PM
> > From: "Andy ZL3AG via time-nuts" >
> > To: "Discussion of precise time and frequency measurement" <
> time-nuts@febo.com >
> > Subject: Re: [time-nuts] I love the smell of tantalum in the morning
> >
> >
> > Yes. Unless you're grinding it away with a dremel (which I wouldn't
> recommend as far as chemical dust is concerned), nibbling away with
> sidecutters would be trying to force the 2 ends of the component apart.
> That may be stressing the pads they're soldered to, leading to a possible
> pad lifting at some stage.
> >
> > Any of the methods mentioned that heat both ends at the same time -
> allowing the component to be wiped off the board - would have to be the
> best, stress-wise.
> ___
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> To unsubscribe, go to https://www.febo.com/cgi-bin/
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> www.febo.com
> time-nuts is a low volume, high SNR list for the discussion of precise
> time and frequency measurement and related topics. To see the collection of
> prior postings to ...
>
>
>
> and follow the instructions there.
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Re: [time-nuts] I love the smell of tantalum in the morning

[Scott Stobbe]

In the case of the rt7 (or knife soldering tips for other brands) you get a
fine point that easily handles 30-32 awg wire, and the edge of the tip is a
little over 100 thou long, so for parts 0805 and smaller you just lay the
edge along the side of the component and heat both pads and swipe it to the
side.

On Sunday, 6 November 2016, Bryan _  wrote:

> If the SMD is small enough I have found it easy to remove by just applying
> a blob of solder to one end, this will quickly gap over to the other lead,
> and the SMD component and solder ball just slides off the board. Only works
> on the very small components though.
>
>
> -=Bryan=-
>
>
> 
> From: time-nuts > on behalf of
> Robert LaJeunesse >
> Sent: November 6, 2016 8:42 AM
> To: time-nuts@febo.com 
> Subject: Re: [time-nuts] I love the smell of tantalum in the morning
>
> Another admittedly low-budget way of heating both ends is to use a heat
> spreader. Solder a short piece of braid to one component end, fold it over
> the top of the part, and solder it to the other end. Heat the braid in the
> center, add solder until both ends are melted, and lift the combination off
> with tweezers. Sometimes a heavy enough copper wire bent around the part
> will also work as the heat spreader..
>
> Bob LaJeunesse
>
> > Sent: Saturday, November 05, 2016 at 9:05 PM
> > From: "Andy ZL3AG via time-nuts" >
> > To: "Discussion of precise time and frequency measurement" <
> time-nuts@febo.com >
> > Subject: Re: [time-nuts] I love the smell of tantalum in the morning
> >
> >
> > Yes. Unless you're grinding it away with a dremel (which I wouldn't
> recommend as far as chemical dust is concerned), nibbling away with
> sidecutters would be trying to force the 2 ends of the component apart.
> That may be stressing the pads they're soldered to, leading to a possible
> pad lifting at some stage.
> >
> > Any of the methods mentioned that heat both ends at the same time -
> allowing the component to be wiped off the board - would have to be the
> best, stress-wise.
> ___
> time-nuts mailing list -- time-nuts@febo.com 
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
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> www.febo.com
> time-nuts is a low volume, high SNR list for the discussion of precise
> time and frequency measurement and related topics. To see the collection of
> prior postings to ...
>
>
>
> and follow the instructions there.
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Re: [time-nuts] I love the smell of tantalum in the morning

[Bryan _]

If the SMD is small enough I have found it easy to remove by just applying a 
blob of solder to one end, this will quickly gap over to the other lead, and 
the SMD component and solder ball just slides off the board. Only works on the 
very small components though.


-=Bryan=-



From: time-nuts  on behalf of Robert LaJeunesse 

Sent: November 6, 2016 8:42 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] I love the smell of tantalum in the morning

Another admittedly low-budget way of heating both ends is to use a heat 
spreader. Solder a short piece of braid to one component end, fold it over the 
top of the part, and solder it to the other end. Heat the braid in the center, 
add solder until both ends are melted, and lift the combination off with 
tweezers. Sometimes a heavy enough copper wire bent around the part will also 
work as the heat spreader..

Bob LaJeunesse

> Sent: Saturday, November 05, 2016 at 9:05 PM
> From: "Andy ZL3AG via time-nuts" 
> To: "Discussion of precise time and frequency measurement" 
> 
> Subject: Re: [time-nuts] I love the smell of tantalum in the morning
>
>
> Yes. Unless you're grinding it away with a dremel (which I wouldn't recommend 
> as far as chemical dust is concerned), nibbling away with sidecutters would 
> be trying to force the 2 ends of the component apart. That may be stressing 
> the pads they're soldered to, leading to a possible pad lifting at some stage.
>
> Any of the methods mentioned that heat both ends at the same time - allowing 
> the component to be wiped off the board - would have to be the best, 
> stress-wise.
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Re: [time-nuts] I love the smell of tantalum in the morning

[William H. Fite]

It's obvious you've never had a manicure, Adrian.
An orangewood stick is an instrument for torturing the cuticles.

Il faut soufrir pour etre belle!



On Sunday, November 6, 2016, Adrian Godwin  wrote:

> You might also want normal cold tweezers to place the part. I'm not sure
> what an orange stick is, around here I'd use a wooden toothpick. Perhaps
> that's the same thing !
>
> The Swiss Venus tweezers have a lovely finish and the ends always meet.
> There are probably others as good.
>
> If you get some placing tweezers, make sure they're antimagnetic. Some
> small parts (even resistors, that I wouldn't expect to contain steel) seem
> to stick even to stainless steel. I've also heard bambooo tweezers are
> good, but have never tried them.
>
>
> On Sun, Nov 6, 2016 at 6:17 PM, jimlux  > wrote:
>
> > On 11/6/16 9:24 AM, Scott Stobbe wrote:
> >
> >> I would not recommend purchasing soldering tweezers without trying them
> >> first. They are not easy to control solder application when mounting a
> >> component.
> >>
> >
> > tweezers to remove
> > single iron to install
> > use a orange stick to hold the part down while you solder each end.
> >
> >
> >
> >
> >
> >
> >
> > ___
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> > ailman/listinfo/time-nuts
> > and follow the instructions there.
> >
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-- 
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Re: [time-nuts] I love the smell of tantalum in the morning

[Adrian Godwin]

You might also want normal cold tweezers to place the part. I'm not sure
what an orange stick is, around here I'd use a wooden toothpick. Perhaps
that's the same thing !

The Swiss Venus tweezers have a lovely finish and the ends always meet.
There are probably others as good.

If you get some placing tweezers, make sure they're antimagnetic. Some
small parts (even resistors, that I wouldn't expect to contain steel) seem
to stick even to stainless steel. I've also heard bambooo tweezers are
good, but have never tried them.


On Sun, Nov 6, 2016 at 6:17 PM, jimlux  wrote:

> On 11/6/16 9:24 AM, Scott Stobbe wrote:
>
>> I would not recommend purchasing soldering tweezers without trying them
>> first. They are not easy to control solder application when mounting a
>> component.
>>
>
> tweezers to remove
> single iron to install
> use a orange stick to hold the part down while you solder each end.
>
>
>
>
>
>
>
> ___
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Re: [time-nuts] I love the smell of tantalum in the morning

[jimlux]

On 11/6/16 9:24 AM, Scott Stobbe wrote:

I would not recommend purchasing soldering tweezers without trying them
first. They are not easy to control solder application when mounting a
component.


tweezers to remove
single iron to install
use a orange stick to hold the part down while you solder each end.






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Re: [time-nuts] I love the smell of tantalum in the morning

[Adrian Godwin]

I agree - I find them totally useless for applying solder. I'd only use
them for removing parts. To solder them, clean the pads as described here
and solder one end at a time.


On Sun, Nov 6, 2016 at 5:24 PM, Scott Stobbe 
wrote:

> I would not recommend purchasing soldering tweezers without trying them
> first. They are not easy to control solder application when mounting a
> component.
>
>  I do really like the Weller rt7 knife tip.
>
> On Sunday, 6 November 2016, Adrian Godwin  wrote:
>
> > SMD parts aren't going to go away. It's worth investing in good tools to
> > deal with them and learning the best way to use them.
> >
> > I'd put tweezers quite high on that list, and although the metcals are
> > worthwhile if you can avoid full price, the chinese tweezers are
> > surprisingly useful at very low cost. Buy them to explore their
> deficiences
> > and buy better when you know what you really need.
> >
> > On Sun, Nov 6, 2016 at 4:53 PM, Clint Jay  > > wrote:
> >
> > > Heating one end and adding a little solder to the joint will allow you
> to
> > > lift the cap,  the leads are folded over tabs so they'll bend nicely
> and
> > > allow the cap to lift,  once you've got one end lifted,  heat the other
> > and
> > > it will come away easily.
> > >
> > > Clean up the pads with solder wick then you're good to replace the
> part.
> > >
> > > While I'd like an excuse (and the funds)  to buy a pair of tweezers for
> > > SMD,  I'd find it hard to use that job as an excuse.
> > >
> > > On 5 Nov 2016 19:12, "Tom Van Baak"  >
> > wrote:
> > >
> > > > See C13 in the attached photo. I need to replace some blown caps on a
> > few
> > > > boards [1]. In one instance the cap got so hot it melted itself off
> the
> > > > board. Quiet convenient, actually -- it acts like its own fuse --
> but I
> > > > don't think the 5071 designers had that clever feature in mind.
> > > >
> > > > Having not done SMT before, how should I do it with minimal risk to
> the
> > > > very precious PCB. Or, what equipment should I use this as a good
> > excuse
> > > to
> > > > buy?
> > > >
> > > > Thanks,
> > > > /tvb
> > > >
> > > > [0] http://www.imdb.com/title/tt0078788/quotes
> > > > [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
> > > >
> > > > ___
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> > > > To unsubscribe, go to https://www.febo.com/cgi-bin/
> > > > mailman/listinfo/time-nuts
> > > > and follow the instructions there.
> > > >
> > > ___
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> > > To unsubscribe, go to https://www.febo.com/cgi-bin/
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> > > and follow the instructions there.
> > >
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Re: [time-nuts] I love the smell of tantalum in the morning

[Scott Stobbe]

I would not recommend purchasing soldering tweezers without trying them
first. They are not easy to control solder application when mounting a
component.

 I do really like the Weller rt7 knife tip.

On Sunday, 6 November 2016, Adrian Godwin  wrote:

> SMD parts aren't going to go away. It's worth investing in good tools to
> deal with them and learning the best way to use them.
>
> I'd put tweezers quite high on that list, and although the metcals are
> worthwhile if you can avoid full price, the chinese tweezers are
> surprisingly useful at very low cost. Buy them to explore their deficiences
> and buy better when you know what you really need.
>
> On Sun, Nov 6, 2016 at 4:53 PM, Clint Jay  > wrote:
>
> > Heating one end and adding a little solder to the joint will allow you to
> > lift the cap,  the leads are folded over tabs so they'll bend nicely and
> > allow the cap to lift,  once you've got one end lifted,  heat the other
> and
> > it will come away easily.
> >
> > Clean up the pads with solder wick then you're good to replace the part.
> >
> > While I'd like an excuse (and the funds)  to buy a pair of tweezers for
> > SMD,  I'd find it hard to use that job as an excuse.
> >
> > On 5 Nov 2016 19:12, "Tom Van Baak" >
> wrote:
> >
> > > See C13 in the attached photo. I need to replace some blown caps on a
> few
> > > boards [1]. In one instance the cap got so hot it melted itself off the
> > > board. Quiet convenient, actually -- it acts like its own fuse -- but I
> > > don't think the 5071 designers had that clever feature in mind.
> > >
> > > Having not done SMT before, how should I do it with minimal risk to the
> > > very precious PCB. Or, what equipment should I use this as a good
> excuse
> > to
> > > buy?
> > >
> > > Thanks,
> > > /tvb
> > >
> > > [0] http://www.imdb.com/title/tt0078788/quotes
> > > [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
> > >
> > > ___
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> > > To unsubscribe, go to https://www.febo.com/cgi-bin/
> > > mailman/listinfo/time-nuts
> > > and follow the instructions there.
> > >
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> > and follow the instructions there.
> >
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Re: [time-nuts] I love the smell of tantalum in the morning

[Adrian Godwin]

SMD parts aren't going to go away. It's worth investing in good tools to
deal with them and learning the best way to use them.

I'd put tweezers quite high on that list, and although the metcals are
worthwhile if you can avoid full price, the chinese tweezers are
surprisingly useful at very low cost. Buy them to explore their deficiences
and buy better when you know what you really need.

On Sun, Nov 6, 2016 at 4:53 PM, Clint Jay  wrote:

> Heating one end and adding a little solder to the joint will allow you to
> lift the cap,  the leads are folded over tabs so they'll bend nicely and
> allow the cap to lift,  once you've got one end lifted,  heat the other and
> it will come away easily.
>
> Clean up the pads with solder wick then you're good to replace the part.
>
> While I'd like an excuse (and the funds)  to buy a pair of tweezers for
> SMD,  I'd find it hard to use that job as an excuse.
>
> On 5 Nov 2016 19:12, "Tom Van Baak"  wrote:
>
> > See C13 in the attached photo. I need to replace some blown caps on a few
> > boards [1]. In one instance the cap got so hot it melted itself off the
> > board. Quiet convenient, actually -- it acts like its own fuse -- but I
> > don't think the 5071 designers had that clever feature in mind.
> >
> > Having not done SMT before, how should I do it with minimal risk to the
> > very precious PCB. Or, what equipment should I use this as a good excuse
> to
> > buy?
> >
> > Thanks,
> > /tvb
> >
> > [0] http://www.imdb.com/title/tt0078788/quotes
> > [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
> >
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> > mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
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Re: [time-nuts] I love the smell of tantalum in the morning

[Clint Jay]

Heating one end and adding a little solder to the joint will allow you to
lift the cap,  the leads are folded over tabs so they'll bend nicely and
allow the cap to lift,  once you've got one end lifted,  heat the other and
it will come away easily.

Clean up the pads with solder wick then you're good to replace the part.

While I'd like an excuse (and the funds)  to buy a pair of tweezers for
SMD,  I'd find it hard to use that job as an excuse.

On 5 Nov 2016 19:12, "Tom Van Baak"  wrote:

> See C13 in the attached photo. I need to replace some blown caps on a few
> boards [1]. In one instance the cap got so hot it melted itself off the
> board. Quiet convenient, actually -- it acts like its own fuse -- but I
> don't think the 5071 designers had that clever feature in mind.
>
> Having not done SMT before, how should I do it with minimal risk to the
> very precious PCB. Or, what equipment should I use this as a good excuse to
> buy?
>
> Thanks,
> /tvb
>
> [0] http://www.imdb.com/title/tt0078788/quotes
> [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
>
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Re: [time-nuts] I love the smell of tantalum in the morning

[Robert LaJeunesse]

Another admittedly low-budget way of heating both ends is to use a heat 
spreader. Solder a short piece of braid to one component end, fold it over the 
top of the part, and solder it to the other end. Heat the braid in the center, 
add solder until both ends are melted, and lift the combination off with 
tweezers. Sometimes a heavy enough copper wire bent around the part will also 
work as the heat spreader..

Bob LaJeunesse

> Sent: Saturday, November 05, 2016 at 9:05 PM
> From: "Andy ZL3AG via time-nuts" 
> To: "Discussion of precise time and frequency measurement" 
> 
> Subject: Re: [time-nuts] I love the smell of tantalum in the morning
>
> 
> Yes. Unless you're grinding it away with a dremel (which I wouldn't recommend 
> as far as chemical dust is concerned), nibbling away with sidecutters would 
> be trying to force the 2 ends of the component apart. That may be stressing 
> the pads they're soldered to, leading to a possible pad lifting at some stage.
> 
> Any of the methods mentioned that heat both ends at the same time - allowing 
> the component to be wiped off the board - would have to be the best, 
> stress-wise.
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Re: [time-nuts] I love the smell of tantalum in the morning

[Christopher Hoover]

Ditto.  I use hot tweezers -- metcal talon handpiece, in my case.   There
are other ways to do it if you don't have them.

On Nov 6, 2016 3:21 AM, "jimlux"  wrote:

> On 11/5/16 12:12 PM, Tom Van Baak wrote:
>
>> See C13 in the attached photo. I need to replace some blown caps on a few
>> boards [1]. In one instance the cap got so hot it melted itself off the
>> board. Quiet convenient, actually -- it acts like its own fuse -- but I
>> don't think the 5071 designers had that clever feature in mind.
>>
>> Having not done SMT before, how should I do it with minimal risk to the
>> very precious PCB. Or, what equipment should I use this as a good excuse to
>> buy?
>>
>>
> Suitable hot tweezers would do this just fine, for both the removal and
> the replacement.
>
> this kind of thing
> http://www.weller-toolsus.com/weller-t0051317199-wta-50-twee
> zers-smd-desoldering.html
> https://www.amazon.com/WMRT-Desoldering-Tweezers-Soldering-
> Stations/dp/B000UMMUII
>
> It's what I've used at work, with a wx2021
> Here's the complete set:
> http://www.weller-toolsus.com/soldering/systems/weller-wx202
> 1-solder-stat-wxmpms-wxmtms-wdh51-wdh60-120v.html
>
> The tips heat basically instantly. It makes it easy to remove/replace even
> tiny stuff, although 0402 is just too small for me.
>
> You need a good magnifier or stereo microscope, and some orange sticks to
> hold things in place while you solder, etc.
>
>
> However, I've been given to understand that there is another superior
> brand (on this list.. )
>
>
>
> Thanks,
>> /tvb
>>
>> [0] http://www.imdb.com/title/tt0078788/quotes
>> [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
>>
>>
>>
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Re: [time-nuts] I love the smell of tantalum in the morning

[Andy ZL3AG via time-nuts]

Yes. Unless you're grinding it away with a dremel (which I wouldn't recommend 
as far as chemical dust is concerned), nibbling away with sidecutters would be 
trying to force the 2 ends of the component apart. That may be stressing the 
pads they're soldered to, leading to a possible pad lifting at some stage.

Any of the methods mentioned that heat both ends at the same time - allowing 
the component to be wiped off the board - would have to be the best, 
stress-wise.

On 6/11/2016, at 3:00 PM, Scott Stobbe wrote:

> For through hole parts sure, but I would not recommend that on SMD parts,
> the copper foil of a little pad is pretty easy to tear off and it's a royal
> pain if you have to mount a device missing some of its landing pads.
> 
> On Sat, Nov 5, 2016 at 4:37 PM, Tom Miller  wrote:
> 
>> I usually nibble away at the center of the part until it is two separate
>> pieces. Then unsolder each piece. Clean the pads off with wick then install
>> the new part.
>> 
>> Use a good sharp pair of flush cut side cutters.
>> 
>> Tom
>> 
>> 

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Re: [time-nuts] I love the smell of tantalum in the morning

[Scott Stobbe]

For through hole parts sure, but I would not recommend that on SMD parts,
the copper foil of a little pad is pretty easy to tear off and it's a royal
pain if you have to mount a device missing some of its landing pads.

On Sat, Nov 5, 2016 at 4:37 PM, Tom Miller  wrote:

> I usually nibble away at the center of the part until it is two separate
> pieces. Then unsolder each piece. Clean the pads off with wick then install
> the new part.
>
> Use a good sharp pair of flush cut side cutters.
>
> Tom
>
>
> - Original Message - From: "Bob Camp" 
> To: "Tom Van Baak" ; "Discussion of precise time and
> frequency measurement" 
> Sent: Saturday, November 05, 2016 4:24 PM
> Subject: Re: [time-nuts] I love the smell of tantalum in the morning
>
>
> Hi
>>
>> A *lot* depends on how many planes there are in that board. The weight of
>> he copper
>> also maters a bit. If there is enough thermal mass, you will need a
>> pre-heat process.
>> There are lots of ways to do it ranging from the kitchen oven to various
>> “frame and
>> lightbulb” setups and on into ever more complex heating approaches.
>>
>> If the hot tweezers / soldering iron / hot air tool does not reflow the
>> solder quickly (10 seconds
>> or less) stop. Get a pre-heat setup and try again. With proper heat you
>> should have the part
>> off in under 4 seconds. People don’t tend to use stopwatches when
>> soldering. 4 seconds is quite
>> a while on a joint. Ten seconds is pretty much forever ….
>>
>> Bob
>>
>> On Nov 5, 2016, at 3:12 PM, Tom Van Baak  wrote:
>>>
>>> See C13 in the attached photo. I need to replace some blown caps on a
>>> few boards [1]. In one instance the cap got so hot it melted itself off the
>>> board. Quiet convenient, actually -- it acts like its own fuse -- but I
>>> don't think the 5071 designers had that clever feature in mind.
>>>
>>> Having not done SMT before, how should I do it with minimal risk to the
>>> very precious PCB. Or, what equipment should I use this as a good excuse to
>>> buy?
>>>
>>> Thanks,
>>> /tvb
>>>
>>> [0] http://www.imdb.com/title/tt0078788/quotes
>>> [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
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>>> ailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
>>
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>>
>
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Re: [time-nuts] I love the smell of tantalum in the morning

[Ian Stirling]

On 11/05/2016 03:12 PM, Tom Van Baak wrote:

> Having not done SMT before, how should I do it with minimal risk to the very 
> precious PCB. Or, what equipment should I use this as a good excuse to buy?

Tom, I used the obvious but never read about using two soldering irons,
invented it myself, or co-discovered.

  Also, a recent addition that makes SMT so easy, the title of the manual is,
"Instruction Manual for SE400, SE400-LED,  Long Working Distance Stereo 
Microscope",
about $200.

  With a working distance of nine inches or so, it beats the pants off my
previous magnifier, Optivisor 10x where I have to have my face less than two
inches from the soldering area.

  .. got the microscope from description from W7ZOI web site.
http://w7zoi.net/micscope.html

Ian, G4ICV, AB2GR
--


 

  

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Re: [time-nuts] I love the smell of tantalum in the morning

[Alexander Pummer]

metcal has a "hot twizer " to remove SMD components it heats the 
component on both end


73

Alex


On 11/5/2016 12:55 PM, Hal Murray wrote:

t...@leapsecond.com said:

Having not done SMT before, how should I do it with minimal risk to the
very precious PCB. Or, what equipment should I use this as a good excuse
to buy?

If you can get at it, 2 soldering irons, one on each end, works reasonably
well.  When both ends are melted, just push the part out of the way.
Small/light things like 0805 resistors will frequently stick to one of the
tops by surface tension of the liquid solder.



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Re: [time-nuts] I love the smell of tantalum in the morning

[David]

On Sat, 5 Nov 2016 20:57:11 +0100, you wrote:

>> Having not done SMT before, how should I do it with minimal risk to the very 
>> precious PCB. Or, what equipment should I use this as a good excuse to buy?
>
>Now, for these caps, you can use a normal soldering-iron without too 
>much trouble, but I strongly recommend pre-heating the board with a 
>hot-air gun.
>
>The trick is to pre-heat the board widely so it becomes hot, but not 
>enough to melt any solder. As you now apply your soldering iron, the 
>heat-transfer won't be as large as if you had a room-temperature board, 
>simply because the lower temperature gradient.
>The effect is that your heating up goes quicker and that part of the 
>board won't experience excess heat for too long.

I have never had a problem removing surface mount parts like that with
just a single soldering iron.  If access is good so that a large heat
capacity tip can be applied, then each solder joint can be heated up
very quickly preventing damage to the board.

Through hole parts on multilayer boards which have a high heat
capacity are a different manner.

>Another trick I use is to solder new solder onto the joints. This breaks 
>through the oxide layer, which is a poor heat conductor. I solder onto 
>the joints and let them cool. Then I come back again and now the 
>soldering iron melts it all up nicely.

On newer boards this is also a great way to dilute the lead free
solder lowering the melting point making removal easier without
damaging the board.

Add some leaded solder and flux to each joint, then remove most of the
solder from each joint with braid, and then a little heat will allow
each side of the part to pop off.

>I still do SMD with my Weller WECP-20, but it's not optimal.
>At work we moved the otherwise so high valued (over-valued) Metcal to 
>the side as the new JBC stations is much better. Metcal's doesn't keep 
>the temperature good enough and the new JBCs is beeter. Metcal's also 
>have a failure-mode in their tips which makes them break way to early. 
>There exist replacement tips which is in fact better than the original.
>
>So, if you need an excuse to buy a new toy, look at the JBC-stuff:
>http://www.jbctools.com/
>
>However, I would probably be able to replace that cap before your get 
>your new and shiny toy on the table.
>
>Cheers,
>Magnus

I still use my ancient Weller Magnestat irons but have quite a
collection of tips including my overpowered vacuum desoldering head.
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Re: [time-nuts] I love the smell of tantalum in the morning

[paul swed]

So much information from so many that have obviously run into the smell of
a burnt part.
I do the cut the part to pieces and unsolder each leg. Also the 2 iron
approach.
The absolute goal, do not damage the board.
I have a hot air station also and much like the comments made not impressed.
I did grab a scrap board to play with as I was learning.
Since your cap looks like it already split in half 50% of the jobs done.
As everyone focuses on the soldering part. The damaged board is equally
critical.
The stuff in tantalums is nasty. I clean the whole area with alcohol. And
at times actually carve out some of the carbon if I can measure some level
of resistance from each trace to the center point.
Your problem looks simple enough Tom.
Just remember this. I hate caps. But have received some of my best
equipment because they fail for $/pound. Kind of a love hate thing.
Regards
Paul
WB8TSL

On Sat, Nov 5, 2016 at 4:37 PM, Tom Miller  wrote:

> I usually nibble away at the center of the part until it is two separate
> pieces. Then unsolder each piece. Clean the pads off with wick then install
> the new part.
>
> Use a good sharp pair of flush cut side cutters.
>
> Tom
>
>
> - Original Message - From: "Bob Camp" 
> To: "Tom Van Baak" ; "Discussion of precise time and
> frequency measurement" 
> Sent: Saturday, November 05, 2016 4:24 PM
> Subject: Re: [time-nuts] I love the smell of tantalum in the morning
>
>
> Hi
>>
>> A *lot* depends on how many planes there are in that board. The weight of
>> he copper
>> also maters a bit. If there is enough thermal mass, you will need a
>> pre-heat process.
>> There are lots of ways to do it ranging from the kitchen oven to various
>> “frame and
>> lightbulb” setups and on into ever more complex heating approaches.
>>
>> If the hot tweezers / soldering iron / hot air tool does not reflow the
>> solder quickly (10 seconds
>> or less) stop. Get a pre-heat setup and try again. With proper heat you
>> should have the part
>> off in under 4 seconds. People don’t tend to use stopwatches when
>> soldering. 4 seconds is quite
>> a while on a joint. Ten seconds is pretty much forever ….
>>
>> Bob
>>
>> On Nov 5, 2016, at 3:12 PM, Tom Van Baak  wrote:
>>>
>>> See C13 in the attached photo. I need to replace some blown caps on a
>>> few boards [1]. In one instance the cap got so hot it melted itself off the
>>> board. Quiet convenient, actually -- it acts like its own fuse -- but I
>>> don't think the 5071 designers had that clever feature in mind.
>>>
>>> Having not done SMT before, how should I do it with minimal risk to the
>>> very precious PCB. Or, what equipment should I use this as a good excuse to
>>> buy?
>>>
>>> Thanks,
>>> /tvb
>>>
>>> [0] http://www.imdb.com/title/tt0078788/quotes
>>> [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
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>>> ailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
>>
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>> ailman/listinfo/time-nuts
>> and follow the instructions there.
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>
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[time-nuts] I love the smell of tantalum in the morning

[Mark Sims]

Tom's method is what I use when replacing commodity parts that I don't care 
about salvaging.  Much less chance of damaging anything.   Hack the part apart, 
 cut the leads on gull wing packages, etc.  Don't waste your time with 
tweezers,  lifting one end, etc.   I have a very nice set of hot tweezers and 
almost never use them.

And for DIP packages cut the package free from the leads first...  even though 
I have a $6000+ vacuum desoldering station,  trying to get all the leads 
unsoldered cleanly and prying out the chip always risks tearing out a feed 
through... particularly on multi-layer boards with out thermal isolation vias 
on power/ground connections.

-

>  I usually nibble away at the center of the part until it is two separate 
pieces. Then unsolder each piece. Clean the pads off with wick then install 
the new part.
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Re: [time-nuts] I love the smell of tantalum in the morning

[Tom Miller]

I usually nibble away at the center of the part until it is two separate 
pieces. Then unsolder each piece. Clean the pads off with wick then install 
the new part.


Use a good sharp pair of flush cut side cutters.

Tom


- Original Message - 
From: "Bob Camp" 
To: "Tom Van Baak" ; "Discussion of precise time and 
frequency measurement" 

Sent: Saturday, November 05, 2016 4:24 PM
Subject: Re: [time-nuts] I love the smell of tantalum in the morning



Hi

A *lot* depends on how many planes there are in that board. The weight of 
he copper
also maters a bit. If there is enough thermal mass, you will need a 
pre-heat process.
There are lots of ways to do it ranging from the kitchen oven to various 
“frame and

lightbulb” setups and on into ever more complex heating approaches.

If the hot tweezers / soldering iron / hot air tool does not reflow the 
solder quickly (10 seconds
or less) stop. Get a pre-heat setup and try again. With proper heat you 
should have the part
off in under 4 seconds. People don’t tend to use stopwatches when 
soldering. 4 seconds is quite

a while on a joint. Ten seconds is pretty much forever ….

Bob


On Nov 5, 2016, at 3:12 PM, Tom Van Baak  wrote:

See C13 in the attached photo. I need to replace some blown caps on a few 
boards [1]. In one instance the cap got so hot it melted itself off the 
board. Quiet convenient, actually -- it acts like its own fuse -- but I 
don't think the 5071 designers had that clever feature in mind.


Having not done SMT before, how should I do it with minimal risk to the 
very precious PCB. Or, what equipment should I use this as a good excuse 
to buy?


Thanks,
/tvb

[0] http://www.imdb.com/title/tt0078788/quotes
[1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
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Re: [time-nuts] I love the smell of tantalum in the morning

[Andrea Baldoni]

On Sat, Nov 05, 2016 at 12:12:18PM -0700, Tom Van Baak wrote:

> Having not done SMT before, how should I do it with minimal risk to
> the very precious PCB. Or, what equipment should I use this as a good
> excuse to buy?

Hello Tom.
I do this kind of repairs quite often and as you have already read from others,
almost every method like hot air, hot tweezers and two irons is suitable.

However, if you have not previous experience of smd reworking and, being
lucky that the component has only two leads, if you can have someone who
will help you and there is enough clearance around the components, I suggest
you use two irons of normal power (> 50W) with flat tip.

Hot air is a much better way to do this work, but it's also more risky:
the temperature and air flux should be right (too low and you will heat too
much everything before desoldering the component, too high and you do the same).
You can end up with melted plastic parts in other components around the area.
In some cases when sensitive components are very near, I build little fences
out of sheet metal to lay on board around the component, letting just the space
to pull up it with tweezers.

To solder back, clean the pads with solder wick, then with some form of
liquid cleaner to remove traces of rosin (I use alcohol, or thinner in some
stubborn cases). Hold the component in position pushing down to the board and
solder it manually at the sides. Forget to use SMD paste and hot air for
soldering. This has not any sense with parts so big and with only two pins
and it's trickier than desoldering about temperature and airflow...

There is another thing to look at. In some process, mainly time ago, the SMD
components were glued before soldering, so the component, even if solder is
already melt, need some force to be pulled up.

Best regards,
Andrea Baldoni
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Re: [time-nuts] I love the smell of tantalum in the morning

[Bob Camp]

Hi

A *lot* depends on how many planes there are in that board. The weight of he 
copper
also maters a bit. If there is enough thermal mass, you will need a pre-heat 
process. 
There are lots of ways to do it ranging from the kitchen oven to various “frame 
and 
lightbulb” setups and on into ever more complex heating approaches. 

If the hot tweezers / soldering iron / hot air tool does not reflow the solder 
quickly (10 seconds 
or less) stop. Get a pre-heat setup and try again. With proper heat you should 
have the part
off in under 4 seconds. People don’t tend to use stopwatches when soldering. 4 
seconds is quite 
a while on a joint. Ten seconds is pretty much forever ….

Bob

> On Nov 5, 2016, at 3:12 PM, Tom Van Baak  wrote:
> 
> See C13 in the attached photo. I need to replace some blown caps on a few 
> boards [1]. In one instance the cap got so hot it melted itself off the 
> board. Quiet convenient, actually -- it acts like its own fuse -- but I don't 
> think the 5071 designers had that clever feature in mind.
> 
> Having not done SMT before, how should I do it with minimal risk to the very 
> precious PCB. Or, what equipment should I use this as a good excuse to buy?
> 
> Thanks,
> /tvb
> 
> [0] http://www.imdb.com/title/tt0078788/quotes
> [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
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Re: [time-nuts] I love the smell of tantalum in the morning

[Tom Van Baak]

Ok, thanks, Chris! Some day I'll learn SMT but I don't think it's wise for me 
to use a 5071 main board as my first mistake. So I'll follow-up with your 
generous offer off-list.

/tvb

  - Original Message - 
  From: Chris Waldrup 
  To: Tom Van Baak ; Discussion of precise time and frequency measurement 
  Sent: Saturday, November 05, 2016 12:58 PM
  Subject: Re: [time-nuts] I love the smell of tantalum in the morning


  Hi Tom,


  I'm a SMT rework technician for a large satcom and defense company. 
  I have a shop at home too and all the equipment to repair this if I can be 
provided with the replacement cap. 
  Please let me know if I can be of help. 


  Chris
  KD4PBJ

  On Nov 5, 2016, at 14:12, Tom Van Baak  wrote:


See C13 in the attached photo. I need to replace some blown caps on a few 
boards [1]. In one instance the cap got so hot it melted itself off the board. 
Quiet convenient, actually -- it acts like its own fuse -- but I don't think 
the 5071 designers had that clever feature in mind.

Having not done SMT before, how should I do it with minimal risk to the 
very precious PCB. Or, what equipment should I use this as a good excuse to buy?

Thanks,
/tvb

[0] http://www.imdb.com/title/tt0078788/quotes
[1] http://leapsecond.com/museum/hp5071a/A1-mother.htm


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Re: [time-nuts] I love the smell of tantalum in the morning

[Chris Waldrup]

Hi Tom,

I'm a SMT rework technician for a large satcom and defense company. 
I have a shop at home too and all the equipment to repair this if I can be 
provided with the replacement cap. 
Please let me know if I can be of help. 

Chris
KD4PBJ

> On Nov 5, 2016, at 14:12, Tom Van Baak  wrote:
> 
> See C13 in the attached photo. I need to replace some blown caps on a few 
> boards [1]. In one instance the cap got so hot it melted itself off the 
> board. Quiet convenient, actually -- it acts like its own fuse -- but I don't 
> think the 5071 designers had that clever feature in mind.
> 
> Having not done SMT before, how should I do it with minimal risk to the very 
> precious PCB. Or, what equipment should I use this as a good excuse to buy?
> 
> Thanks,
> /tvb
> 
> [0] http://www.imdb.com/title/tt0078788/quotes
> [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
> 
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Re: [time-nuts] I love the smell of tantalum in the morning

[Magnus Danielson]

Dear Tom,

On 11/05/2016 08:12 PM, Tom Van Baak wrote:

See C13 in the attached photo. I need to replace some blown caps on a few 
boards [1]. In one instance the cap got so hot it melted itself off the board. 
Quiet convenient, actually -- it acts like its own fuse -- but I don't think 
the 5071 designers had that clever feature in mind.


You're clearly lucky, one failure mode is short-circuit, and they can 
bring other stuff with them as they fail, and hence hated by some.



Having not done SMT before, how should I do it with minimal risk to the very 
precious PCB. Or, what equipment should I use this as a good excuse to buy?


Now, for these caps, you can use a normal soldering-iron without too 
much trouble, but I strongly recommend pre-heating the board with a 
hot-air gun.


The trick is to pre-heat the board widely so it becomes hot, but not 
enough to melt any solder. As you now apply your soldering iron, the 
heat-transfer won't be as large as if you had a room-temperature board, 
simply because the lower temperature gradient.
The effect is that your heating up goes quicker and that part of the 
board won't experience excess heat for too long.


Another trick I use is to solder new solder onto the joints. This breaks 
through the oxide layer, which is a poor heat conductor. I solder onto 
the joints and let them cool. Then I come back again and now the 
soldering iron melts it all up nicely.


I still do SMD with my Weller WECP-20, but it's not optimal.
At work we moved the otherwise so high valued (over-valued) Metcal to 
the side as the new JBC stations is much better. Metcal's doesn't keep 
the temperature good enough and the new JBCs is beeter. Metcal's also 
have a failure-mode in their tips which makes them break way to early. 
There exist replacement tips which is in fact better than the original.


So, if you need an excuse to buy a new toy, look at the JBC-stuff:
http://www.jbctools.com/

However, I would probably be able to replace that cap before your get 
your new and shiny toy on the table.


Cheers,
Magnus
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Re: [time-nuts] I love the smell of tantalum in the morning

[Hal Murray]

t...@leapsecond.com said:
> Having not done SMT before, how should I do it with minimal risk to the
> very precious PCB. Or, what equipment should I use this as a good excuse
> to buy? 

If you can get at it, 2 soldering irons, one on each end, works reasonably 
well.  When both ends are melted, just push the part out of the way.  
Small/light things like 0805 resistors will frequently stick to one of the 
tops by surface tension of the liquid solder.

-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] I love the smell of tantalum in the morning

[Bob Stewart]

Hi John,

I've never used the hot tweezers.  I'm going to have to look into them.  
Normally, for desoldering, I use a narrower nozzle with an elevated temperature 
- usually between 280C and 350C.  That blows the part completely off the pads 
just as soon as the solder flows, with little impact on adjacent components.  
For soldering, since I use a 240C leaded solder paste, i use a larger nozzle 
with slower air flow at about 245C-260C depending on what I'm soldering.  
Desoldering against a copper plane is always a problem regardless of the 
thermal pad's shape.  I'd think you'd need a pretty hot set of tweezers to get 
a big 1210 sized tantalum off the board if there's a ground plane.

Bob
 -
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info

  From: John Ackermann N8UR 
 To: time-nuts@febo.com 
 Sent: Saturday, November 5, 2016 2:35 PM
 Subject: Re: [time-nuts] I love the smell of tantalum in the morning
   
Either hot tweezers or a hot air rework station are the best/easiest 
ways to remove dead parts.  But two fine-tip soldering irons will also 
work and are a lot cheaper.  The idea is to heat both ends of the part 
at once, and when the solder flows, lift or flip the part off.  Then, 
use some liquid flux and narrow solder wick to suck off the excess 
solder, and you should end up with nice smooth pads ready for the 
replacement part.

The key thing to avoid damage is to make sure the solder is really 
flowing on both pads before you try to lift the part.  Sometimes ground 
pads have enough thermal mass that it takes a while to get them hot 
enough.  Be patient.

Good luck!
John


On 11/05/2016 03:12 PM, Tom Van Baak wrote:
> See C13 in the attached photo. I need to replace some blown caps on a few 
> boards [1]. In one instance the cap got so hot it melted itself off the 
> board. Quiet convenient, actually -- it acts like its own fuse -- but I don't 
> think the 5071 designers had that clever feature in mind.
>
> Having not done SMT before, how should I do it with minimal risk to the very 
> precious PCB. Or, what equipment should I use this as a good excuse to buy?
>
> Thanks,
> /tvb
>
> [0] http://www.imdb.com/title/tt0078788/quotes
> [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
>
>
>
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Re: [time-nuts] I love the smell of tantalum in the morning

[Bryan _]

Surprisingly the 852D+ which is a very cheap rework station is quite good. 
Quite a few reviews on the EEVblog.


-=Bryan=-



From: time-nuts  on behalf of Bob Stewart 

Sent: November 5, 2016 12:18 PM
To: Tom Van Baak; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] I love the smell of tantalum in the morning

Hi Tom,
Personally, I wouldn't touch this without a hot air gun.  I don't know what 
your budget is.  What I consider reasonable may be an order of magnitude 
smaller than for you.  So, I use a generically labeled 852D+ rework combo.  It 
has both solder pencil and hot air gun.  There are better hot air guns for a 
reasonable price that have a better system for changing the nozzles.  OTOH, 
I've heard some complaints about this "better" system where the nozzle has 
fallen off.  If you've got a Pace soldering system, then you already know what 
to do.  =)

Bob




  From: Tom Van Baak 
 To: Discussion of precise time and frequency measurement 
 Sent: Saturday, November 5, 2016 2:12 PM
 Subject: [time-nuts] I love the smell of tantalum in the morning

See C13 in the attached photo. I need to replace some blown caps on a few 
boards [1]. In one instance the cap got so hot it melted itself off the board. 
Quiet convenient, actually -- it acts like its own fuse -- but I don't think 
the 5071 designers had that clever feature in mind.

Having not done SMT before, how should I do it with minimal risk to the very 
precious PCB. Or, what equipment should I use this as a good excuse to buy?

Thanks,
/tvb

[0] http://www.imdb.com/title/tt0078788/quotes
[https://images-na.ssl-images-amazon.com/images/M/MV5BYWNjNjZjYmMtOTRjOC00ZGIwLWI2YzEtMjkxNTAzODkzZDRlXkEyXkFqcGdeQXVyNjUwNzk3NDc@._V1_UY98_CR0]

Apocalypse Now (1979) - Quotes - 
IMDb
www.imdb.com
Apocalypse Now (1979) Quotes on IMDb: Memorable quotes and exchanges from 
movies, TV series and more...



[1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
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Re: [time-nuts] I love the smell of tantalum in the morning

[John Ackermann N8UR]

Either hot tweezers or a hot air rework station are the best/easiest 
ways to remove dead parts.  But two fine-tip soldering irons will also 
work and are a lot cheaper.  The idea is to heat both ends of the part 
at once, and when the solder flows, lift or flip the part off.  Then, 
use some liquid flux and narrow solder wick to suck off the excess 
solder, and you should end up with nice smooth pads ready for the 
replacement part.


The key thing to avoid damage is to make sure the solder is really 
flowing on both pads before you try to lift the part.  Sometimes ground 
pads have enough thermal mass that it takes a while to get them hot 
enough.  Be patient.


Good luck!
John


On 11/05/2016 03:12 PM, Tom Van Baak wrote:

See C13 in the attached photo. I need to replace some blown caps on a few 
boards [1]. In one instance the cap got so hot it melted itself off the board. 
Quiet convenient, actually -- it acts like its own fuse -- but I don't think 
the 5071 designers had that clever feature in mind.

Having not done SMT before, how should I do it with minimal risk to the very 
precious PCB. Or, what equipment should I use this as a good excuse to buy?

Thanks,
/tvb

[0] http://www.imdb.com/title/tt0078788/quotes
[1] http://leapsecond.com/museum/hp5071a/A1-mother.htm



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Re: [time-nuts] I love the smell of tantalum in the morning

[Bruce Griffiths]

On Saturday, November 05, 2016 12:12:18 PM Tom Van Baak wrote:
> See C13 in the attached photo. I need to replace some blown caps on a 
few
> boards [1]. In one instance the cap got so hot it melted itself off the
> board. Quiet convenient, actually -- it acts like its own fuse -- but I
> don't think the 5071 designers had that clever feature in mind.
> 
> Having not done SMT before, how should I do it with minimal risk to the 
very
> precious PCB. Or, what equipment should I use this as a good excuse to 
buy?
> 
> Thanks,
> /tvb
> 
> [0] http://www.imdb.com/title/tt0078788/quotes
> [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
Tom

Either a hot air jet as used for smt desoldering will work.
A variety of nozzle shapes and sizes are available.

or

One can use a fine tip iron to alloy the solder with a low melting point 
solder alloy making it very easy to remove the component and then 
cleanup the pads using fluxed copper braid or even a cotton bud. Its 
essential to remove the low melting point alloy before resoldering.
 
CHIPQUIK SMD N1 works well with both leaded and unleaded soldered SMT 
parts
Bob Pease touted RF induction heated irons. Hakko makes a nice one 
(FX100) now the patent has expired.

Bruce
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Re: [time-nuts] I love the smell of tantalum in the morning

[Adrian Godwin]

Metcal /OKI might be that other brand. I'd certainly recommend them, but
the tweezers are not as fast to heat as the single tip devices.

I've had little success personally with the hot air devices. I seem to
toast the board before I melt the solder, and when it does melt it's not
limited to one component. Doubtless it's my technique at fault, but I
prefer the tweezers.






On Sat, Nov 5, 2016 at 7:20 PM, jimlux  wrote:

> On 11/5/16 12:12 PM, Tom Van Baak wrote:
>
>> See C13 in the attached photo. I need to replace some blown caps on a few
>> boards [1]. In one instance the cap got so hot it melted itself off the
>> board. Quiet convenient, actually -- it acts like its own fuse -- but I
>> don't think the 5071 designers had that clever feature in mind.
>>
>> Having not done SMT before, how should I do it with minimal risk to the
>> very precious PCB. Or, what equipment should I use this as a good excuse to
>> buy?
>>
>>
> Suitable hot tweezers would do this just fine, for both the removal and
> the replacement.
>
> this kind of thing
> http://www.weller-toolsus.com/weller-t0051317199-wta-50-twee
> zers-smd-desoldering.html
> https://www.amazon.com/WMRT-Desoldering-Tweezers-Soldering-
> Stations/dp/B000UMMUII
>
> It's what I've used at work, with a wx2021
> Here's the complete set:
> http://www.weller-toolsus.com/soldering/systems/weller-wx202
> 1-solder-stat-wxmpms-wxmtms-wdh51-wdh60-120v.html
>
> The tips heat basically instantly. It makes it easy to remove/replace even
> tiny stuff, although 0402 is just too small for me.
>
> You need a good magnifier or stereo microscope, and some orange sticks to
> hold things in place while you solder, etc.
>
>
> However, I've been given to understand that there is another superior
> brand (on this list.. )
>
>
>
> Thanks,
>> /tvb
>>
>> [0] http://www.imdb.com/title/tt0078788/quotes
>> [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
>>
>>
>>
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Re: [time-nuts] I love the smell of tantalum in the morning

[Bob Stewart]

Hi Tom,
Personally, I wouldn't touch this without a hot air gun.  I don't know what 
your budget is.  What I consider reasonable may be an order of magnitude 
smaller than for you.  So, I use a generically labeled 852D+ rework combo.  It 
has both solder pencil and hot air gun.  There are better hot air guns for a 
reasonable price that have a better system for changing the nozzles.  OTOH, 
I've heard some complaints about this "better" system where the nozzle has 
fallen off.  If you've got a Pace soldering system, then you already know what 
to do.  =)

Bob




  From: Tom Van Baak 
 To: Discussion of precise time and frequency measurement  
 Sent: Saturday, November 5, 2016 2:12 PM
 Subject: [time-nuts] I love the smell of tantalum in the morning
   
See C13 in the attached photo. I need to replace some blown caps on a few 
boards [1]. In one instance the cap got so hot it melted itself off the board. 
Quiet convenient, actually -- it acts like its own fuse -- but I don't think 
the 5071 designers had that clever feature in mind.

Having not done SMT before, how should I do it with minimal risk to the very 
precious PCB. Or, what equipment should I use this as a good excuse to buy?

Thanks,
/tvb

[0] http://www.imdb.com/title/tt0078788/quotes
[1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
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Re: [time-nuts] I love the smell of tantalum in the morning

[jimlux]

On 11/5/16 12:12 PM, Tom Van Baak wrote:

See C13 in the attached photo. I need to replace some blown caps on a few 
boards [1]. In one instance the cap got so hot it melted itself off the board. 
Quiet convenient, actually -- it acts like its own fuse -- but I don't think 
the 5071 designers had that clever feature in mind.

Having not done SMT before, how should I do it with minimal risk to the very 
precious PCB. Or, what equipment should I use this as a good excuse to buy?



Suitable hot tweezers would do this just fine, for both the removal and 
the replacement.


this kind of thing
http://www.weller-toolsus.com/weller-t0051317199-wta-50-tweezers-smd-desoldering.html
https://www.amazon.com/WMRT-Desoldering-Tweezers-Soldering-Stations/dp/B000UMMUII

It's what I've used at work, with a wx2021
Here's the complete set:
http://www.weller-toolsus.com/soldering/systems/weller-wx2021-solder-stat-wxmpms-wxmtms-wdh51-wdh60-120v.html

The tips heat basically instantly. It makes it easy to remove/replace 
even tiny stuff, although 0402 is just too small for me.


You need a good magnifier or stereo microscope, and some orange sticks 
to hold things in place while you solder, etc.



However, I've been given to understand that there is another superior 
brand (on this list.. )





Thanks,
/tvb

[0] http://www.imdb.com/title/tt0078788/quotes
[1] http://leapsecond.com/museum/hp5071a/A1-mother.htm



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