I thought I wrote it but I didn't.
Your 3.3v read 14.4, mine read 19.6.
I'm just noting that for now. Not sure if it's a problem or not.
It may be that we have a jumper of switch on different settings.
Paar wrote:I have no way to know which caps are on the +5V rail.
Do a resistance check between the +5v pin in the PSU connector (rather the solder point for it as you will be on that side of the board) and the pins to the caps.
Any that read zero are on the +5v rail.
If you pull one out and the problem with the +5v reading from earlier goes away then you found the last shorted one on +5v.. Checking the +5v to ground after pulling each cap might save you some time.
Paar wrote:I could try to do complete recap
As you are so determined I say go for it. The caps are like 20 years old and don't last forever.
I counted 20 caps and all but one look easy.
That 6.3mm near the CPU slot might be harder to get out but still not THAT hard.
Do a Cap-Map first. Don't want to get them out then forget which way was negative.
If the crystals are cheap you might consider just replacing those too.
Please don't spend more than the board or the experience is worth to you.
The outlook is not good on something like this. It just isn't.
Paar wrote:Could replace all +5V regulators as well.
I wouldn't blanket replace those. Least not the ICs.
The back side is usually soldered all across and they are a bugger to change out.
Look up the numbers on them and find the datasheets.
Most can be checked with a DMM but they aren't all 'wired' the same.
There are tutorials online that tell how to check them.
I can't promise to be here often as I have a busy time ITRW coming up.
Checking the little SMD parts right near them isn't a bad idea.
You/we are expecting shorted caps at this point.
Shorted ones don't need much to find them once they are out.
Shorted is shorted. Capacitance and ESR don't even matter for that.
An analog resistance meter works better but you can sort-a do it with a DMM.
=Connect the leads, the reading should rise as the meter charges the cap.
=Reverse the leads. Should start negative/go to zero/then repeat what it did on the other side.
That is the charge you just put on it discharging and then it charges up again the other way.
If you get a low reading or not much response both ways the cap is shorted or partially shorted.
This is easier to do on an analog meter because you can watch the needle move as the cap charges/discharges. DMM's are harder for this because it's hard to tell if rapidly changing numbers on the display are going up or down. It can be done with a DMM. It's just not so easy.
Obviously you have a DMM but I dunno what other equipment you have available.
I also dunno your skill level but so far you seem to know what you're doing.
[I am not suggesting you buy one. Just telling things to consider if you want one.]
You do not HAVE to have an analog meter. It's just easier for this check with one.
You do NOT need an expensive one. A $10-$15 cheapie is fine for this kind of check.
One with a reasonably sized meter face is a good idea.
The very tiny ones are hard to read and almost useless if you ever need it for actual numbers rather than just to see a trend.
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