Re: Memory Tech you don't see very often

[Eric Smith via cctalk]

On Thu, Jan 6, 2022, 01:20 Joshua Rice via cctech 
wrote:

>
> Not cost effective at nearly $10,000! I understand they're very rare,
> given they were only used for a few years in industry and they're
> clocking on 3/4 of a century old, but even then, that seems an order of
> magnitude or two off the real value.
>

The rarity wasn't that only one _model_ of computer used it. Only one
_unit_ used it. It used 80 tubes at a cost of around $500 each, in
mid-20th-century dollars.

Given that they'd have needed some spares and replacements, the production
run would have been more than 80 pieces, but I'd think it unlikely that
more than 250 production units were ever made.

If someone wants one and is able to purchase it for $10,000, I think they
are very lucky.

Re: Source for replacement caps in H744 regulators

[Jon Elson via cctalk]

On 1/6/22 6:04 PM, Matt Burke via cctalk wrote:


Quiet regulator: http://www.9track.net/posts/h744/h744_ba11_q2e.png
Noisy regulator: http://www.9track.net/posts/h744/h744_ts11_q2e.png

The yellow trace is the emitter of Q2 (input of L1) and the cyan trace
is the output of L1. Q2 seems to be switching partly on then fully on in
the noisy regulator. it should of course be fully on or fully off as
seen on the quiet regulator. Also the switching frequency seems to be lower.

Yes, the 2nd unit is running at 5 KHz, clearly explaining 
the noise.  Possibly there is a bad flyback diode, or 
something causing the different waveform.


Jon

Re: Memory Tech you don't see very often

[Eric Smith via cctalk]

On Thu, Jan 6, 2022, 08:45 Mike Katz via cctalk 
wrote:

> There was also a 1K by 4 version of this tube.
>

I've never seen any info on a 1K*4 Selectron, but they weren't even able to
make the 4K*1 work, and the only production tubes were 256*1.

Re: Source for replacement caps in H744 regulators

[Brent Hilpert via cctalk]

On 2022-Jan-06, at 4:04 PM, Matt Burke via cctalk wrote:
> On 06/01/2022 12:59, Jonathan Chapman via cctalk wrote:
>> That said, it's not like replacing them with new will *hurt* -- it just 
>> might not fix the whine.
> 
> I suspect that it won't fix the problem. Slightly hijacking the thread
> here but hopefully in a semi-helpful way.
> 
> I have two of these regulators, one from a BA11K and one from a TS11.
> Under the same test conditions the one from the TS11 produces a
> significantly louder whining noise than the one from the BA11K. Given
> that they are largely the same circuit as the H745 regulators and all
> the ones I have are silent in operation I find it hard to believe they
> are supposed to be like this. I used to have two more TS11 drives and
> they both exhibited the same behaviour. Seems to be a common problem.
> 
> Now, for the one from the BA11K (quiet one) the output capacitors were
> completely open (0uF) so I had to replace them. Given that I had the new
> capacitors I decided to try them in the TS11 regulator to see if it
> would fix the whining noise. It made no difference.
> 
> After some probing with an oscilloscope I found that between the two
> regulators there was a very different waveform on the emitter of Q2.
> 
> Quiet regulator: http://www.9track.net/posts/h744/h744_ba11_q2e.png
> Noisy regulator: http://www.9track.net/posts/h744/h744_ts11_q2e.png
> 
> The yellow trace is the emitter of Q2 (input of L1) and the cyan trace
> is the output of L1. Q2 seems to be switching partly on then fully on in
> the noisy regulator. it should of course be fully on or fully off as
> seen on the quiet regulator. Also the switching frequency seems to be lower.


The intermediate step voltage at Q2.E-L1.input is not Q2 partially on. It's D5 
shutting off, as it would do when L1 has discharged and current is no longer 
flowing in it, and follows from the basic principles of a buck converter. 
Notice that the step is 5V, i.e. the output voltage.


> I tried testing/swapping a few parts between the two regulators, L1, Q2,
> Q3, E1. It started out reasonably logical and after several days
> descended into a unscientific mess of swapping anything and everything
> that could possibly be at fault. I got to the point where I had
> eliminated just about every component so I must have overlooked
> something. I was hoping to stumble upon the answer and then learn
> something from it but so far no luck. This project has been shelved for
> a while now.

RE: Source for replacement caps in H744 regulators

[W2HX via cctalk]

My 2c. I am not familiar with a "whine" but certainly a "hum." Sometimes if a 
power supply has seen a lot of heavy load over its lifetime, the heat generated 
can begin to do things to the transformer. And once that heat has done its 
"thing" to the transformer, it stays that way. And no replacing external 
components will change the hum. However, there are some transformers with bolts 
and nuts that hold the laminations together. Sometimes they can be tightened to 
reduce the hum. I don’t know this PS specifically and whether it falls into 
this category or not.

I don’t know if what you are hearing is transformer hum, but if it is, you may 
just have to live with it.

73 Eugene W2HX
Subscribe to my Youtube Channel: https://www.youtube.com/c/w2hx-channel/videos



-Original Message-
From: cctalk  On Behalf Of Matt Burke via cctalk
Sent: Thursday, January 6, 2022 7:05 PM
To: cctalk@classiccmp.org
Subject: Re: Source for replacement caps in H744 regulators

On 06/01/2022 12:59, Jonathan Chapman via cctalk wrote:
> That said, it's not like replacing them with new will *hurt* -- it just might 
> not fix the whine.

I suspect that it won't fix the problem. Slightly hijacking the thread here but 
hopefully in a semi-helpful way.

I have two of these regulators, one from a BA11K and one from a TS11.
Under the same test conditions the one from the TS11 produces a significantly 
louder whining noise than the one from the BA11K. Given that they are largely 
the same circuit as the H745 regulators and all the ones I have are silent in 
operation I find it hard to believe they are supposed to be like this. I used 
to have two more TS11 drives and they both exhibited the same behaviour. Seems 
to be a common problem.

Now, for the one from the BA11K (quiet one) the output capacitors were 
completely open (0uF) so I had to replace them. Given that I had the new 
capacitors I decided to try them in the TS11 regulator to see if it would fix 
the whining noise. It made no difference.

After some probing with an oscilloscope I found that between the two regulators 
there was a very different waveform on the emitter of Q2.

Quiet regulator: http://www.9track.net/posts/h744/h744_ba11_q2e.png
Noisy regulator: http://www.9track.net/posts/h744/h744_ts11_q2e.png

The yellow trace is the emitter of Q2 (input of L1) and the cyan trace is the 
output of L1. Q2 seems to be switching partly on then fully on in the noisy 
regulator. it should of course be fully on or fully off as seen on the quiet 
regulator. Also the switching frequency seems to be lower.

I tried testing/swapping a few parts between the two regulators, L1, Q2, Q3, 
E1. It started out reasonably logical and after several days descended into a 
unscientific mess of swapping anything and everything that could possibly be at 
fault. I got to the point where I had eliminated just about every component so 
I must have overlooked something. I was hoping to stumble upon the answer and 
then learn something from it but so far no luck. This project has been shelved 
for a while now.

Regards,

Matt

Re: Source for replacement caps in H744 regulators

[Matt Burke via cctalk]

On 06/01/2022 12:59, Jonathan Chapman via cctalk wrote:
> That said, it's not like replacing them with new will *hurt* -- it just might 
> not fix the whine.

I suspect that it won't fix the problem. Slightly hijacking the thread
here but hopefully in a semi-helpful way.

I have two of these regulators, one from a BA11K and one from a TS11.
Under the same test conditions the one from the TS11 produces a
significantly louder whining noise than the one from the BA11K. Given
that they are largely the same circuit as the H745 regulators and all
the ones I have are silent in operation I find it hard to believe they
are supposed to be like this. I used to have two more TS11 drives and
they both exhibited the same behaviour. Seems to be a common problem.

Now, for the one from the BA11K (quiet one) the output capacitors were
completely open (0uF) so I had to replace them. Given that I had the new
capacitors I decided to try them in the TS11 regulator to see if it
would fix the whining noise. It made no difference.

After some probing with an oscilloscope I found that between the two
regulators there was a very different waveform on the emitter of Q2.

Quiet regulator: http://www.9track.net/posts/h744/h744_ba11_q2e.png
Noisy regulator: http://www.9track.net/posts/h744/h744_ts11_q2e.png

The yellow trace is the emitter of Q2 (input of L1) and the cyan trace
is the output of L1. Q2 seems to be switching partly on then fully on in
the noisy regulator. it should of course be fully on or fully off as
seen on the quiet regulator. Also the switching frequency seems to be lower.

I tried testing/swapping a few parts between the two regulators, L1, Q2,
Q3, E1. It started out reasonably logical and after several days
descended into a unscientific mess of swapping anything and everything
that could possibly be at fault. I got to the point where I had
eliminated just about every component so I must have overlooked
something. I was hoping to stumble upon the answer and then learn
something from it but so far no luck. This project has been shelved for
a while now.

Regards,

Matt

What happened to Bill Whitson?

[Ryan Ottignon via cctalk]

Bill Whitson, the original ClassicCmp ListOp, has a surprisingly little amount 
of information available about him online. Does anyone know what happened to 
him after the late 90s? (If anyone has any contact information, that would be 
nice!)

Ryan Ottignon

Re: Source for replacement caps in H744 regulators

[Bill Degnan via cctalk]

It would be a lot easier to replace the large circular regulator if you're
taking the shotgun approach, and much more likely that the regulator is a
source of faults.  and it's cheaper.  For the h744, 45, 54.  BUT measuring
things is the best way if you can do it.   Pull the values from the
backplane, there are test points that you can measure from.
Bill

On Thu, Jan 6, 2022 at 2:30 PM Wayne S via cctech 
wrote:

> So you want to replace capacitors just because they “whine” ?
> I’ll say that because you are learning, that is not good troubleshooting
> practice.
> Make a checklist of troubleshooting power supplies.
> There are a lot of good youtube videos  and other internet information  on
> how power supplies work, how to check them and repair them. There is danger
> when working  with power supplies.
> When working on electrical equipment do you know about the  “working with
> one hand in your pocket rule?” Doing this stuff, videos and reading, is not
> overly time consuming and may save your life!
>
>
>
> Sent from my iPhone
>
> > On Jan 6, 2022, at 07:50, Jon Elson via cctalk 
> wrote:
> >
> > On 1/6/22 2:52 AM, Rob Jarratt via cctalk wrote:
> >> I think I may need to replace the two output capacitors in some of my
> H744
> >> regulators. These are screw terminal 6,000uF 10V parts. I have looked on
> >> Mouser, Farnell and Digikey and there don't seem to be any available,
> and
> >> any that are listed are really rather costly.
> >>
> >>
> >> Does anyone know where I might find some, preferably from a reputable
> >> supplier. Note that I am in the UK.
> >>
> >>
> >
> > Mouser is a good place to find big caps (or at least used to be).  You
> might have to get "snap in" caps and solder wires to them, that style seems
> to be more available.
> >
> > Jon
> >
>

Re: Memory Tech you don't see very often

[Paul Koning via cctalk]

> On Jan 6, 2022, at 2:11 PM, Chuck Guzis via cctalk  
> wrote:
> 
> On 1/6/22 10:17, William Donzelli wrote:
>> If you include prototypes, then you need to include ALL the prototypes
>> - even things made in single quantities that never worked.
>> 
>> That is a HUGE amount of stuff that makes EBAM look gigantic.
> 
> To be fair, EBAM received a not-insignificant amount of press coverage.
> What doomed it was the falling cost and increasing density of
> semiconductor memory.  Good idea, wrong time.
> 
> It was pitched in a few forward-looking responses to government RFPs.
> But then, so was a lot of other stuff.

So what is an EBAM tube?  Google turns up very little; I found a reference in a 
1977 textbook (courtesy Google Books) that makes it sound like a synonym for 
"Williams tube".  Those were decades obsolete by then; so what were these 
things and why were they being considered in the days of not just semicondutor 
memory but also core memory?

Selectrons are weird devices, but just like (nearly all) core memory they use 
coincidence addressing to keep the control logic complexity reasonable, a very 
significant consideration in the days of vacuum tube logic.  And actually the 
addressing is even more clever so it scales with the 1/4th power of the memory 
size (same as core does if you put current switches at both ends of the X/Y 
wires).

A 1948 discussion of memory technology concepts makes fascinating reading; it 
includes wild stuff like photographic film and paper marked by electric 
discharge, along with familiar stuff like drum and acoustic memory.  But the 
drum discussion suggests that a drum might be spun at 60,000 rpm -- which would 
certainly do wonders for performance but it's puzzling where that dream came 
from.

paul

Re: Memory Tech you don't see very often

[Chuck Guzis via cctalk]

On 1/6/22 10:17, William Donzelli wrote:
> If you include prototypes, then you need to include ALL the prototypes
> - even things made in single quantities that never worked.
> 
> That is a HUGE amount of stuff that makes EBAM look gigantic.

To be fair, EBAM received a not-insignificant amount of press coverage.
 What doomed it was the falling cost and increasing density of
semiconductor memory.  Good idea, wrong time.

It was pitched in a few forward-looking responses to government RFPs.
But then, so was a lot of other stuff.

--Chuck

Re: Memory Tech you don't see very often

[William Donzelli via cctalk]

Prototypes don't count.

--
Will

On Thu, Jan 6, 2022 at 12:41 PM Chuck Guzis via cctech
 wrote:
>
>
> Perhaps even rarer were the EBAM tubes that CDC worked with during the
> 1970s.  I recall seeing a 6' rack of a complete assembly sitting in a
> hallway at ADL around 1974.  If CDC followed the dictates of management
> then, the unit was probably utterly demolsihed before being sold as
> scrap metal.
>
> --Chuck
>
>
>

Re: Memory Tech you don't see very often

[Chuck Guzis via cctalk]

Perhaps even rarer were the EBAM tubes that CDC worked with during the
1970s.  I recall seeing a 6' rack of a complete assembly sitting in a
hallway at ADL around 1974.  If CDC followed the dictates of management
then, the unit was probably utterly demolsihed before being sold as
scrap metal.

--Chuck

Re: Source for replacement caps in H744 regulators

[Jon Elson via cctalk]

On 1/6/22 2:52 AM, Rob Jarratt via cctalk wrote:

I think I may need to replace the two output capacitors in some of my H744
regulators. These are screw terminal 6,000uF 10V parts. I have looked on
Mouser, Farnell and Digikey and there don't seem to be any available, and
any that are listed are really rather costly.

  


Does anyone know where I might find some, preferably from a reputable
supplier. Note that I am in the UK.

  


Mouser is a good place to find big caps (or at least used to 
be).  You might have to get "snap in" caps and solder wires 
to them, that style seems to be more available.


Jon

Re: Memory Tech you don't see very often

[Mike Katz via cctalk]

There was also a 1K by 4 version of this tube.

On 1/6/2022 3:03 AM, Brent Hilpert via cctalk wrote:

On 2022-Jan-06, at 12:19 AM, Joshua Rice via cctech wrote:

Not cost effective at nearly $10,000! I understand they're very rare, given 
they were only used for a few years in industry and they're clocking on 3/4 of 
a century old, but even then, that seems an order of magnitude or two off the 
real value.
Actually, looking them up, doesn't seem they were used in much at all. Seems to 
have been a bit of a technological dead-end since core memory quickly 
superseded it with it's (relatively) cheap costs and (relative) ease of 
manufacturing. I imagine the US gov. probably used them somewhere, since they 
were a sucker for cutting edge technology of the time.
Would be interesting to know how many hours it's got on it

"Not cost effective" ?  What does that mean in the arena of valuation of 
historic artifacts?

No, they didn't go anywhere as a product and apparently only saw use in one 
machine.

However, the 'pro' side of such a debate is that they were a very early attempt 
to produce a fast digital RAM memory specifically for use in Stored-Program 
Machines, at a time when memory was at the top of the list of problems in 
development of the first SPMs, and actually before any SPMs had been produced, 
and weren't a serial technology like drums and delays lines tortured into 
applicability for the task.

They are wrapped up in the history of John VonN and the IAS machine, one of the 
most significant machines in computing history (arguably the most significant).

There's always opinion and subjective valuation in assessments of history but 
if one is acquainted with what was going on in that period of 46-50, they are a 
very interesting and notable development attempt.




-- Original Message --
From: "pbirkel--- via cctalk" 
To: "'General Discussion: On-Topic Posts'" 
Sent: Wednesday, 5 Jan, 2022 At 17:35
Subject: Memory Tech you don't see very often
Selectron Vacuum Tube: https://www.ebay.com/itm/174977901251 


Really nice photo-shoot! I wonder what the back-story to this particular
tube might be.

I don't think that $16.18 shipping would be, um, adequate protection by any
measure.
Cheap, but not so sure about "cost-effective" .

Re: Memory Tech you don't see very often

[Paul Koning via cctalk]

> On Jan 6, 2022, at 4:06 AM, Brent Hilpert via cctalk  
> wrote:
> 
> On 2022-Jan-06, at 12:19 AM, Joshua Rice via cctech wrote:
>> Not cost effective at nearly $10,000! I understand they're very rare, given 
>> they were only used for a few years in industry and they're clocking on 3/4 
>> of a century old, but even then, that seems an order of magnitude or two off 
>> the real value.
>> Actually, looking them up, doesn't seem they were used in much at all. Seems 
>> to have been a bit of a technological dead-end since core memory quickly 
>> superseded it with it's (relatively) cheap costs and (relative) ease of 
>> manufacturing. I imagine the US gov. probably used them somewhere, since 
>> they were a sucker for cutting edge technology of the time.
>> Would be interesting to know how many hours it's got on it
> 
> "Not cost effective" ?  What does that mean in the arena of valuation of 
> historic artifacts?
> 
> No, they didn't go anywhere as a product and apparently only saw use in one 
> machine.
> 
> However, the 'pro' side of such a debate is that they were a very early 
> attempt to produce a fast digital RAM memory specifically for use in 
> Stored-Program Machines, at a time when memory was at the top of the list of 
> problems in development of the first SPMs, and actually before any SPMs had 
> been produced, and weren't a serial technology like drums and delays lines 
> tortured into applicability for the task.

Yes, for example in van Wijngaarden's 1948 course text "principles of 
electronic calculating machines", the Selectron is explained in detail (as a 4k 
bit device, which apparently was the original hope).  It also mentions 
something like a Williams tube (not by that name, so perhaps it's not exactly 
that).  The only other idea for a random-access RAM that it mentions is a 
rather vague notion that a crossbar of gas discharge elements could be used.  
That was later (1960) used as a display device, the famous plasma panel display 
invented by Don Bitzer et al.; not clear if it was ever actually used as a 
memory device.  Core memory does not appear in that 1948 document, that's a 
later invention but indeed the one that ended up successful in practice.

paul

RE: Source for replacement caps in H744 regulators

[Rob Jarratt via cctalk]

> -Original Message-
> From: cctalk  On Behalf Of Peter Coghlan
> via cctalk
> Sent: 06 January 2022 12:16
> To: General Discussion: On-Topic and Off-Topic Posts
> 
> Subject: RE: Source for replacement caps in H744 regulators
> 
> 
> >
> >> -Original Message-
> >> From: cctalk  On Behalf Of Christian
> >> Corti via cctalk
> >> Sent: 06 January 2022 10:02
> >> To: General Discussion: On-Topic and Off-Topic Posts
> >> 
> >> Subject: Re: Source for replacement caps in H744 regulators
> >>
> >> On Thu, 6 Jan 2022, r...@jarratt.me.uk wrote:
> >> > If I can't find 10V rated ones, then, generally up to what sort of
> >> > voltage rating can I go? Of course, physical size will be a factor,
> >> > but electrically can it affect operation of the regulator if the
> >> > rated
> > voltage is
> >> too high?
> >>
> >> If you need to ask this, are you sure you want to do electronics
repair?
> >
> > I am gradually learning.
> >
> 
> I'm slowly picking this sort of stuff up as I go along too.
> 
> I think that asking questions like this is the right thing to do when we
are not
> sure about something and is not at all an indication that someone is
> somehow not suited to the task.  Quite the reverse in fact.
> 
> If we don't do this sort of work ourselves, it's not going to be easy to
get
> someone else to do it and make sure it is done well for a
> reasonable price.   Any contemporary electronics repair outfit, assuming
> one can be found, would probably recommend dumping the whole thing and
> replacing it with a "modern" power supply.
> 
> >
> >> And what makes you think that you need to replace these caps at all?
> >
> 
> I appreciate that there is lots of bogus advice out there which suggests
that
> all capacitors need to be replaced before even starting to investigate the
> cause of problems but I think Rob has demonstrated that he is trying to
> figure out what is going on rather than just blindly replacing stuff.
> 
> >
> > One of the H744 regulators whines and I have been told it could be the
> > ESR on these caps. I have measured the ESR on these particular ones
> > (out of
> > circuit) and it seems higher than the expected values printed on the
> > meter and also the ESR is not stable, it fluctuates randomly. This
> > suggests the cap is not in great condition.
> >
> 
> I guess from that the large capacitance of these units, they are probably
> filtering 50Hz or 100Hz ripple and high ESR is probably going to lead to
higher
> than normal levels of ripple on the output which could possibly cause some
> inductive component somewhere to buzz or whine.
> 
> I'm not sure if it is easy to measure the ripple on the output or if it is
specified
> anywhere how much ripple can be tolerated before logic errors start to
> become a problem.
> 
> Maybe it would be good to replace the capacitors in just the unit which is
> whining to begin with and see if it makes a difference?

I will try this by using the caps from other H744s that don't whine.

> 
> To address the original question, I think I read somewhere that
electrolytic
> capacitors that are used for voltages a lot lower than their rating may
fail to
> maintain their dielectric formation which may in turn result in increased
> leakage.
> 
> Here's a thought.  Could the whining be coming from an inductive filter
> before the capactors because of excessive leakage through the capacitors
> rather than because of high ESR? Would they benefit from re-forming?

I did re-form the capacitors first. They didn't seem to need much as I ran
them at 10V with zero leakage current (i.e. not measurable). Maybe I need to
run the reforming process a bit longer anyway?

> 
> Regards,
> Peter Coghlan.
> 
> >
> >>
> >> Christian
> >

RE: Source for replacement caps in H744 regulators

[Rob Jarratt via cctalk]

> -Original Message-
> From: Jonathan Chapman 
> Sent: 06 January 2022 13:00
> To: r...@jarratt.me.uk; Rob Jarratt ; General
> Discussion: On-Topic and Off-Topic Posts 
> Subject: RE: Source for replacement caps in H744 regulators
> 
> > One of the H744 regulators whines
> 
> FWIW, none of mine are silent under load. If they're not being loaded (e.g.
> on a test bench, with no dummy load, or if you have all the boards out) they
> can whine excessively due to no minimum load.

I was testing with a 1R resistor, so drawing 5A of the rated 25A. The other two 
H744s did not whine, but this one does. I can try a bigger load, I think the 
best I may be able to do is 10A, possibly 20A.

> 
> > it seems higher than the expected values printed on the meter
> 
> Beware cheap test equipment. $client has a few of these Chinese handheld
> LC/RLC meters, they're wildly inaccurate on some parameters, including ESR
> on large electrolytics. We've got a proper Gen-Rad RLC Digibridge in the shop
> to compare against. We couldn't figure out why some of their tuned filter
> stages were failing QC at a much higher rate than expected. They were off-
> frequency because the cheap meters were giving consistently incorrect
> measurements when trying to match capacitors.
> 

My ESR meter is built from a design by Bob Parker. I got it from someone in 
Portugal (https://evbesrmeter.pt/), so I don't think it is a cheap Chinese one.

> That said, it's not like replacing them with new will *hurt* -- it just might 
> not
> fix the whine.
> 
> Thanks,
> Jonathan

RE: Source for replacement caps in H744 regulators

[Peter Coghlan via cctalk]

>
>> -Original Message-
>> From: cctalk  On Behalf Of Christian Corti
>> via cctalk
>> Sent: 06 January 2022 10:02
>> To: General Discussion: On-Topic and Off-Topic Posts
>> 
>> Subject: Re: Source for replacement caps in H744 regulators
>> 
>> On Thu, 6 Jan 2022, r...@jarratt.me.uk wrote:
>> > If I can't find 10V rated ones, then, generally up to what sort of
>> > voltage rating can I go? Of course, physical size will be a factor,
>> > but electrically can it affect operation of the regulator if the rated
> voltage is
>> too high?
>> 
>> If you need to ask this, are you sure you want to do electronics repair?
>
> I am gradually learning.
>

I'm slowly picking this sort of stuff up as I go along too.

I think that asking questions like this is the right thing to do when we
are not sure about something and is not at all an indication that someone
is somehow not suited to the task.  Quite the reverse in fact.

If we don't do this sort of work ourselves, it's not going to be easy
to get someone else to do it and make sure it is done well for a
reasonable price.   Any contemporary electronics repair outfit, assuming
one can be found, would probably recommend dumping the whole thing and
replacing it with a "modern" power supply.

>
>> And what makes you think that you need to replace these caps at all?
>

I appreciate that there is lots of bogus advice out there which suggests
that all capacitors need to be replaced before even starting to investigate
the cause of problems but I think Rob has demonstrated that he is trying
to figure out what is going on rather than just blindly replacing stuff.

>
> One of the H744 regulators whines and I have been told it could be the ESR
> on these caps. I have measured the ESR on these particular ones (out of
> circuit) and it seems higher than the expected values printed on the meter
> and also the ESR is not stable, it fluctuates randomly. This suggests the
> cap is not in great condition.
>

I guess from that the large capacitance of these units, they are probably
filtering 50Hz or 100Hz ripple and high ESR is probably going to lead to
higher than normal levels of ripple on the output which could possibly
cause some inductive component somewhere to buzz or whine.

I'm not sure if it is easy to measure the ripple on the output or if
it is specified anywhere how much ripple can be tolerated before logic
errors start to become a problem.

Maybe it would be good to replace the capacitors in just the unit which
is whining to begin with and see if it makes a difference?

To address the original question, I think I read somewhere that electrolytic
capacitors that are used for voltages a lot lower than their rating may
fail to maintain their dielectric formation which may in turn result in
increased leakage.

Here's a thought.  Could the whining be coming from an inductive filter
before the capactors because of excessive leakage through the capacitors
rather than because of high ESR? Would they benefit from re-forming?

Regards,
Peter Coghlan.

>
>> 
>> Christian
>

RE: Source for replacement caps in H744 regulators

[Jonathan Chapman via cctalk]

> One of the H744 regulators whines

FWIW, none of mine are silent under load. If they're not being loaded (e.g. on 
a test bench, with no dummy load, or if you have all the boards out) they can 
whine excessively due to no minimum load.

> it seems higher than the expected values printed on the meter

Beware cheap test equipment. $client has a few of these Chinese handheld LC/RLC 
meters, they're wildly inaccurate on some parameters, including ESR on large 
electrolytics. We've got a proper Gen-Rad RLC Digibridge in the shop to compare 
against. We couldn't figure out why some of their tuned filter stages were 
failing QC at a much higher rate than expected. They were off-frequency because 
the cheap meters were giving consistently incorrect measurements when trying to 
match capacitors.

That said, it's not like replacing them with new will *hurt* -- it just might 
not fix the whine.

Thanks,
Jonathan

RE: Source for replacement caps in H744 regulators

[Rob Jarratt via cctalk]

> -Original Message-
> From: cctalk  On Behalf Of Christian Corti
> via cctalk
> Sent: 06 January 2022 10:02
> To: General Discussion: On-Topic and Off-Topic Posts
> 
> Subject: Re: Source for replacement caps in H744 regulators
> 
> On Thu, 6 Jan 2022, r...@jarratt.me.uk wrote:
> > If I can't find 10V rated ones, then, generally up to what sort of
> > voltage rating can I go? Of course, physical size will be a factor,
> > but electrically can it affect operation of the regulator if the rated
voltage is
> too high?
> 
> If you need to ask this, are you sure you want to do electronics repair?

I am gradually learning.

> And what makes you think that you need to replace these caps at all?

One of the H744 regulators whines and I have been told it could be the ESR
on these caps. I have measured the ESR on these particular ones (out of
circuit) and it seems higher than the expected values printed on the meter
and also the ESR is not stable, it fluctuates randomly. This suggests the
cap is not in great condition.

> 
> Christian

RE: Source for replacement caps in H744 regulators

[Dave Wade G4UGM via cctalk]

Rob,

The voltage rating is just an absolute maximum. For PSU capacitors the other
critical rating is ripple current. Lower voltages are 
The capacitance value won't be too critical either. At the time that was
made typical electrolytic tolerances were -50/+100%
So your 6,000uf could be anywhere between 3,000uf and 12,000uf when new, so
I suspect these

https://uk.rs-online.com/web/p/aluminium-capacitors/8556059

Sprague, 5,800uf 50v would be ok provided they physically fit... although RS
has only one in stock...

Dave

> -Original Message-
> From: cctalk  On Behalf Of Rob Jarratt via
> cctalk
> Sent: 06 January 2022 08:53
> To: General Discussion: On-Topic and Off-Topic Posts
> 
> Subject: Source for replacement caps in H744 regulators
> 
> I think I may need to replace the two output capacitors in some of my H744
> regulators. These are screw terminal 6,000uF 10V parts. I have looked on
> Mouser, Farnell and Digikey and there don't seem to be any available, and
> any that are listed are really rather costly.
> 
> 
> 
> Does anyone know where I might find some, preferably from a reputable
> supplier. Note that I am in the UK.
> 
> 
> 
> If I can't find 10V rated ones, then, generally up to what sort of voltage
rating
> can I go? Of course, physical size will be a factor, but electrically can
it affect
> operation of the regulator if the rated voltage is too high?
> 
> 
> 
> Thanks
> 
> 
> 
> Rob

Re: Source for replacement caps in H744 regulators

[Christian Corti via cctalk]

On Thu, 6 Jan 2022, r...@jarratt.me.uk wrote:

If I can't find 10V rated ones, then, generally up to what sort of voltage
rating can I go? Of course, physical size will be a factor, but electrically
can it affect operation of the regulator if the rated voltage is too high?


If you need to ask this, are you sure you want to do electronics repair?
And what makes you think that you need to replace these caps at all?

Christian

Re: Source for replacement caps in H744 regulators

[Matt Burke via cctalk]

On 06/01/2022 08:52, Rob Jarratt via cctalk wrote:
> I think I may need to replace the two output capacitors in some of my H744
> regulators. These are screw terminal 6,000uF 10V parts. I have looked on
> Mouser, Farnell and Digikey and there don't seem to be any available, and
> any that are listed are really rather costly. 

I think I used Mouser part number80-PEH169HA460AQU2 to replace mine. I
was also considering RS part number 381-9093 as an alternative though
the voltage rating is quite a bit higher.

Regards,

Matt

Re: Memory Tech you don't see very often

[Brent Hilpert via cctalk]

On 2022-Jan-06, at 12:19 AM, Joshua Rice via cctech wrote:
> Not cost effective at nearly $10,000! I understand they're very rare, given 
> they were only used for a few years in industry and they're clocking on 3/4 
> of a century old, but even then, that seems an order of magnitude or two off 
> the real value.
> Actually, looking them up, doesn't seem they were used in much at all. Seems 
> to have been a bit of a technological dead-end since core memory quickly 
> superseded it with it's (relatively) cheap costs and (relative) ease of 
> manufacturing. I imagine the US gov. probably used them somewhere, since they 
> were a sucker for cutting edge technology of the time.
> Would be interesting to know how many hours it's got on it

"Not cost effective" ?  What does that mean in the arena of valuation of 
historic artifacts?

No, they didn't go anywhere as a product and apparently only saw use in one 
machine.

However, the 'pro' side of such a debate is that they were a very early attempt 
to produce a fast digital RAM memory specifically for use in Stored-Program 
Machines, at a time when memory was at the top of the list of problems in 
development of the first SPMs, and actually before any SPMs had been produced, 
and weren't a serial technology like drums and delays lines tortured into 
applicability for the task.

They are wrapped up in the history of John VonN and the IAS machine, one of the 
most significant machines in computing history (arguably the most significant).

There's always opinion and subjective valuation in assessments of history but 
if one is acquainted with what was going on in that period of 46-50, they are a 
very interesting and notable development attempt.



> -- Original Message --
> From: "pbirkel--- via cctalk" 
> To: "'General Discussion: On-Topic Posts'" 
> Sent: Wednesday, 5 Jan, 2022 At 17:35
> Subject: Memory Tech you don't see very often
> Selectron Vacuum Tube: https://www.ebay.com/itm/174977901251 
> 
> 
> Really nice photo-shoot! I wonder what the back-story to this particular
> tube might be.
> 
> I don't think that $16.18 shipping would be, um, adequate protection by any
> measure.
> Cheap, but not so sure about "cost-effective" .

Re: Memory Tech you don't see very often

[Joshua Rice via cctalk]

Not cost effective at nearly $10,000! I understand they're very rare, 
given they were only used for a few years in industry and they're 
clocking on 3/4 of a century old, but even then, that seems an order of 
magnitude or two off the real value.
Actually, looking them up, doesn't seem they were used in much at all. 
Seems to have been a bit of a technological dead-end since core memory 
quickly superseded it with it's (relatively) cheap costs and (relative) 
ease of manufacturing. I imagine the US gov. probably used them 
somewhere, since they were a sucker for cutting edge technology of the 
time.

Would be interesting to know how many hours it's got on it

-- Original Message --
From: "pbirkel--- via cctalk" 
To: "'General Discussion: On-Topic Posts'" 
Sent: Wednesday, 5 Jan, 2022 At 17:35
Subject: Memory Tech you don't see very often
Selectron Vacuum Tube: https://www.ebay.com/itm/174977901251 



Really nice photo-shoot! I wonder what the back-story to this particular
tube might be.

I don't think that $16.18 shipping would be, um, adequate protection by 
any

measure.
Cheap, but not so sure about "cost-effective" .

-

Re: Memory Tech you don't see very often

[Brent Hilpert via cctalk]

On 2022-Jan-06, at 12:19 AM, Joshua Rice via cctech wrote:
> Not cost effective at nearly $10,000! I understand they're very rare, given 
> they were only used for a few years in industry and they're clocking on 3/4 
> of a century old, but even then, that seems an order of magnitude or two off 
> the real value.
> Actually, looking them up, doesn't seem they were used in much at all. Seems 
> to have been a bit of a technological dead-end since core memory quickly 
> superseded it with it's (relatively) cheap costs and (relative) ease of 
> manufacturing. I imagine the US gov. probably used them somewhere, since they 
> were a sucker for cutting edge technology of the time.
> Would be interesting to know how many hours it's got on it

"Not cost effective" ?  What does that mean in the arena of valuation of 
historic artifacts?

No, they didn't go anywhere as a product and apparently only saw use in one 
machine.

However, the 'pro' side of such a debate is that they were a very early attempt 
to produce a fast digital RAM memory specifically for use in Stored-Program 
Machines, at a time when memory was at the top of the list of problems in 
development of the first SPMs, and actually before any SPMs had been produced, 
and weren't a serial technology like drums and delays lines tortured into 
applicability for the task.

They are wrapped up in the history of John VonN and the IAS machine, one of the 
most significant machines in computing history (arguably the most significant).

There's always opinion and subjective valuation in assessments of history but 
if one is acquainted with what was going on in that period of 46-50, they are a 
very interesting and notable development attempt.



> -- Original Message --
> From: "pbirkel--- via cctalk" 
> To: "'General Discussion: On-Topic Posts'" 
> Sent: Wednesday, 5 Jan, 2022 At 17:35
> Subject: Memory Tech you don't see very often
> Selectron Vacuum Tube: https://www.ebay.com/itm/174977901251 
> 
> 
> Really nice photo-shoot! I wonder what the back-story to this particular
> tube might be.
> 
> I don't think that $16.18 shipping would be, um, adequate protection by any
> measure.
> Cheap, but not so sure about "cost-effective" .

Source for replacement caps in H744 regulators

[Rob Jarratt via cctalk]

I think I may need to replace the two output capacitors in some of my H744
regulators. These are screw terminal 6,000uF 10V parts. I have looked on
Mouser, Farnell and Digikey and there don't seem to be any available, and
any that are listed are really rather costly.

 

Does anyone know where I might find some, preferably from a reputable
supplier. Note that I am in the UK.

 

If I can't find 10V rated ones, then, generally up to what sort of voltage
rating can I go? Of course, physical size will be a factor, but electrically
can it affect operation of the regulator if the rated voltage is too high?

 

Thanks

 

Rob