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Identifying a Capacitor

Thread starter #1
Hello all,

Just acquired a beautiful Compaq Deskpro 386s/20n and, after replacing 3 unhappy capacitors in the power supply, I'm still unable to get it to boot. I then removed the motherboard from the equation and the HDD spun up!

So... dead MB. Question is, can I also revive that? I voted yes, but in that process I came across the following:





On top is "10" then "16v" and the polarity of the pins.
I want to assume they are 10uf.. electrolytic.. and I want to replace them... but... are they?

Google images is not returning any results for any such thing as a rectangular electrolytic.

Of course, replacing these could do nothing... chances are if the power surge has made it through the board to these and cooked these and the PS then the system is dead... but all's well that ends well.

Thank you to anyone in advance that has seen (and is able to describe) such a component!

Update: I powered the system up after nudging the capacitor, as per the image above, and power is staying active, rather than shorting straight away... might head to the electronics store as soon as positive identification is confirmed.
 
Last edited:

JimB

Super Moderator
Most Helpful Member
#2
Yes, 10uF 16volt.

JimB
 
Thread starter #3
Thankyou!
Had some in the toolkit... replaced them... now the fan is 'ticking' again... i.e. the power supply is tripping. DAMN.
Time to work out the pinout... it's totally proprietary!

 

spec

Well-Known Member
Most Helpful Member
#4
Hy stevenh,

Those capacitors are almost certainly supply line decouples, and are probably 10uF 16V, as you say, which would be a reasonable spec for a PC main board. The capacitors are probably solid aluminum polymer polarized capacitors, some of which were troublesome when they first came out. https://en.wikipedia.org/wiki/Polymer_capacitor

I would have thought that if you fitted 10uF to 22uF replacements with a working voltage of at least 16V they should be fine.:) Look for a low and consistent Effective Series Resistance (ESR) with temperature.

spec

(crossed with posts #2 and #3 above)
 
Thread starter #5
I replaced with boring-off-the-shelf 10uf 16v electrolytics... unfortunately it seems that the power supply has retired after I replaced it's 1000uf 10v (when the circuit was 12v) electros.
I think I might just reverse the pinout and engineer an ATX supply into it.
The reversing could be the new reason this thread exists. Stay tuned :)
 

spec

Well-Known Member
Most Helpful Member
#6
I replaced with boring-off-the-shelf 10uf 16v electrolytics... unfortunately it seems that the power supply has retired after I replaced it's 1000uf 10v (when the circuit was 12v) electros.
I think I might just reverse the pinout and engineer an ATX supply into it.
The reversing could be the new reason this thread exists. Stay tuned :)
Sounds like a good move.:p

spec
 

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