Re: [q] Centris 650 Problems

[Nick]

--- Jeff Walther <[EMAIL PROTECTED]> wrote:

> >Date: Tue, 6 Dec 2005 16:56:46 -0800 (PST)
> >From: Nick <[EMAIL PROTECTED]>
> >Subject: [q] Centris 650 Problems
> 
> >I was hoping someone could give me some suggestions
> >for a sick Centris 650.  I had it in storage for a
> >while and before I put it in, it worked great. 
> Once I
> >took it out, however, I couldn't get it to turn on
> at
> >all.  It appears to be dead.  I can't get the fan
> to
> >come on or get a chime or anything.  As far as I
> can
> >tell, everything is fine.  I even pulled the SIMMs
> to
> >see if that would help.  I also replaced the PRAM
> >battery and nothing worked.  At this point, I am at
> a
> >loss.
> 
> >At any rate, I would appreciate any suggestions or
> >tips anyone can offer me on getting this Centris
> 650
> >back from the grave.  I'd hate to scrap it as it's
> a
> >fine machine.

There motherboard and power supply are perfectly
clean.  No dark stains.  

> Most likely the some capacitors in the power supply
> or on the 
> motherboard have given up the ghost.  Examine the
> motherboard 
> carefully for a slightly dark discoloration around
> the area where the 
> power supply plugs into the MB.   If it looks like
> there's a cola 
> stain on there, then your surface mount electrolytic
> capacitors (look 
> like tiny silver storage tanks) have leaked their
> electrolyte onto 
> the board.
> 
> If the MB caps have leaked you could have three
> problems.  The 
> electrolyte is somewhat conductive and can cause
> shorts.  This is 
> corrected by cleaning the MB.  Some folks run them
> through the 
> dishwasher, but I recommend a careful scrubbing with
> 91% isopropyl 
> alcohol (or spray with Flux remover and scrub).  A
> soft bristle or 
> worn out toothbrush is good for scrubbing.
> 
> The electrolyte is corrosive and may have eaten
> through traces, 
> solder joints or vias (conductive holes through the
> motherboard) on 
> the motherboard.  If this is the case, you would
> need to identify the 
> damaged area and either resolder damaged solder
> joints or bypass with 
> wire wrap (for damaged traces or vias).

As far as I can tell, all the capacitors are fine.  I
have read about the "capacitor plague" but I think
that's been more recent and has mostly effected PC
hardware.  The power supply circuit boards looke clean
too.  And even if I could just replace the caps, I
have zero skill with a soldering iron.

> There are about four of these caps that are
> important to the power-on 
> circuitry.  If those caps stop working, then the
> machine won't stay 
> on.  However, this problem more commonly has the
> symptom that the 
> machine powers on for a moment and then turns off. 
> If these caps are 
> dead then you need to replace them.  If you have
> leaky caps, you 
> really ought to replace them all anyway, because
> they could continue 
> to leak.   If you use two 15W soldering pencils
> (Radio Shack <$10 
> each) it is easy to remove the surface mount caps. 
> Just apply one 
> pencil to each side and gently lift the cap when it
> comes loose.

I'm kind of looking for a no cost/super low cost
solution as I'm a college student.  Much of the Mac
stuff I have is from Goodwill or sometimes people just
giving their old stuff away.  If I ever pick up a
compatible power supply or motherboard I could plop
those in.  But I wouldn't want to gut a working Quadra
just to revive a Centris.

> Alternatively, your power supply may be history. 
> Again, the 
> electrolytic capacitors in the supply are the most
> likely culprit, 
> but this time you'd be dealing with through-hole
> caps rather than 
> tiny surface mount caps.   Replacing the caps in the
> power supply 
> might fix it.

Do you know anything about the fuse?  

> You can use the power supply from the following Macs
> in the Centris 
> 650:  Mac IICX, IICI, IIvi, IIvx, Q700, C650, Q650,
> PM7100.
> 
> Motherboards for the Centris 650 are not uncommon on
> Ebay and 
> generally under $15.  You can also use the
> motherboard from a Quadra 
> 650 or a Q800.   Your CPU chip is almost certainly
> still fine, so you 
> could even get a MB with no CPU and just move it
> over, which might 
> save you a bit.   I like the seller, Olde Mac Milt
> (olde-mac-milt), 
> so you might contact him and see if he has a C or
> Q650 motherboard 
> available.

Thanks very much for your help.

> Oops, just checked and it looks like he's in the
> process of moving.
> 
> Jeff Walther
> 
> -- 
> Quadlist is sponsored by &l

Re: [q] Centris 650 Problems

[Jeff Walther]

Date: Tue, 6 Dec 2005 16:56:46 -0800 (PST)
From: Nick <[EMAIL PROTECTED]>
Subject: [q] Centris 650 Problems



I was hoping someone could give me some suggestions
for a sick Centris 650.  I had it in storage for a
while and before I put it in, it worked great.  Once I
took it out, however, I couldn't get it to turn on at
all.  It appears to be dead.  I can't get the fan to
come on or get a chime or anything.  As far as I can
tell, everything is fine.  I even pulled the SIMMs to
see if that would help.  I also replaced the PRAM
battery and nothing worked.  At this point, I am at a
loss.



At any rate, I would appreciate any suggestions or
tips anyone can offer me on getting this Centris 650
back from the grave.  I'd hate to scrap it as it's a
fine machine.


Most likely the some capacitors in the power supply or on the 
motherboard have given up the ghost.  Examine the motherboard 
carefully for a slightly dark discoloration around the area where the 
power supply plugs into the MB.   If it looks like there's a cola 
stain on there, then your surface mount electrolytic capacitors (look 
like tiny silver storage tanks) have leaked their electrolyte onto 
the board.


If the MB caps have leaked you could have three problems.  The 
electrolyte is somewhat conductive and can cause shorts.  This is 
corrected by cleaning the MB.  Some folks run them through the 
dishwasher, but I recommend a careful scrubbing with 91% isopropyl 
alcohol (or spray with Flux remover and scrub).  A soft bristle or 
worn out toothbrush is good for scrubbing.


The electrolyte is corrosive and may have eaten through traces, 
solder joints or vias (conductive holes through the motherboard) on 
the motherboard.  If this is the case, you would need to identify the 
damaged area and either resolder damaged solder joints or bypass with 
wire wrap (for damaged traces or vias).


There are about four of these caps that are important to the power-on 
circuitry.  If those caps stop working, then the machine won't stay 
on.  However, this problem more commonly has the symptom that the 
machine powers on for a moment and then turns off.  If these caps are 
dead then you need to replace them.  If you have leaky caps, you 
really ought to replace them all anyway, because they could continue 
to leak.   If you use two 15W soldering pencils (Radio Shack <$10 
each) it is easy to remove the surface mount caps.  Just apply one 
pencil to each side and gently lift the cap when it comes loose.


Alternatively, your power supply may be history.  Again, the 
electrolytic capacitors in the supply are the most likely culprit, 
but this time you'd be dealing with through-hole caps rather than 
tiny surface mount caps.   Replacing the caps in the power supply 
might fix it.


You can use the power supply from the following Macs in the Centris 
650:  Mac IICX, IICI, IIvi, IIvx, Q700, C650, Q650, PM7100.


Motherboards for the Centris 650 are not uncommon on Ebay and 
generally under $15.  You can also use the motherboard from a Quadra 
650 or a Q800.   Your CPU chip is almost certainly still fine, so you 
could even get a MB with no CPU and just move it over, which might 
save you a bit.   I like the seller, Olde Mac Milt (olde-mac-milt), 
so you might contact him and see if he has a C or Q650 motherboard 
available.


Oops, just checked and it looks like he's in the process of moving.

Jeff Walther

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[q] Centris 650 Problems

[Nick]

Greetings,

I was hoping someone could give me some suggestions
for a sick Centris 650.  I had it in storage for a
while and before I put it in, it worked great.  Once I
took it out, however, I couldn't get it to turn on at
all.  It appears to be dead.  I can't get the fan to
come on or get a chime or anything.  As far as I can
tell, everything is fine.  I even pulled the SIMMs to
see if that would help.  I also replaced the PRAM
battery and nothing worked.  At this point, I am at a
loss.  The only thing I can think of trying is to
replace the fuse in the power supply.  I have no idea
if the fuse is blown or not (it's opaque so I can't
see the filament) but I figure it's worth a try. 
Unfortunately, I can't find a replacement fuse around
here.

At any rate, I would appreciate any suggestions or
tips anyone can offer me on getting this Centris 650
back from the grave.  I'd hate to scrap it as it's a
fine machine.

Thank you.

-Nick



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