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aguerrero810
March 4th, 2017, 07:10 PM
The seller of the machine said the computer worked fine until he turned it on one day and it popped. When I took the rear cover off the computer, I saw two busted Tantalum Capacitors, but I've heard that on some IBM machines they don't matter. It almost sounds like its under too much load and restarting constantly. I also checked the Power Supply, but everything looked fine in there. Here's a video of the symptoms.

https://www.youtube.com/watch?v=2ZaZ8F9bs7w
Thanks!

modem7
March 5th, 2017, 10:13 PM
... I saw two busted Tantalum Capacitors, but I've heard that on some IBM machines they don't matter.
For the IBM machines that you write of, the capacitors that can be left out and not affect motherboard (repeat: motherboard) operation, are in specific locations within the circuit. Other capacitors on the same motherboards do have an effect. For example, the tantalum capacitors that service the RAM are very important (failure resulting in nil or flakey RAM operation).

pcdata76
March 6th, 2017, 12:46 AM
I've got an IBM PS/2 Model 80 last year from a recycler. Computer was working perfect except it couldn't manage to keep CMOS settings despite the new battery. Then, I've carefully inspected the board and saw that none of the tantalums were in place :D They were all cut from their legs and discarded.

My theory here is that after the explosion of few of them, somebody saw that the computer is working without them and then thought that they are unnecessary and removed all as a precautionary measure :P I've installed electrolytics (they were all three legged tantalums originally) and CMOS issue has then gone.

aguerrero810
March 14th, 2017, 04:56 PM
So I got the computer to work after removing one of the Tantalums. I was working with it for a while then it stopped again. I think I'm going to do what you are saying. So they can just be replaced directly with electrolytics?

Thanks!
Anthony

pcdata76
March 16th, 2017, 10:34 AM
So it means that the tantalum which you've removed was causing a short and kicking the short circuit protection of the power supply. Don't continue with them cause they may pop and make you a firework show :)

You can safely replace tantalums with electrolytics having the same capacitance value and at least same voltage. They are long replaced with modern electrolyric/polymer caps and used rarely now. Just be careful about the polarity. In tantalums, marking is located for the positive pole but in electrolytics for the negative. I replace tantalums with eqivalent electrolytics all the time when they've failed.

FJB
December 1st, 2018, 08:54 AM
How do you get the cover off of the Power Supply? Thank you!