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Old 07-24-2008, 02:54 PM   #1
robofind
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Default Compaq Evo D510 SFF - worked 30 minutes after recapp and than stopped.

The computer is Compaq Evo D510 SFF, with motherboard spare part number 277977-001 (where SFF means Small Form Factor). The processor is P4 2GHz, on socket 478.

1. For many years the computer was worked fine without any problems.
2. One day is suddenly "freezes" and, after waiting some time, it is shut down from the power botton. And it no longer boots.
3. I tought "It is a semiconductor device - the capacitors do not fail so suddenly". But there were 13 bad capacitors, most of them in the processor core voltage regulator.
4. They were National Chemi-Con KZG 2200uF, 6.3V, which have ESR of 12 mOhm.
5. I replaced them with Hitano EXR with the same value, but they have ESR of 68 mOhm.
6. The system started and worked fine for about 30 minutes. Then it restarted, and again it was not able to boot. After a rest of about 5 minutes it was able to start again. This time it worked about 5 minutes and got "frozen".
7. That was - the system is in its initial condition, can not start.

The question is - what is the problem, the ESR of the capacitors?
Or there is something else that I did not got in consideration?
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Old 07-29-2008, 08:14 AM   #2
Gianni
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Default Re: Compaq Evo D510 SFF - worked 30 minutes after recapp and than stopped.

Quote:
Originally Posted by robofind
The question is - what is the problem, the ESR of the capacitors?
Or there is something else that I did not got in consideration?
In my recent experience I can say that ESR can't be the problem.
If the motherboard won't start at all check everything as usual: short circuit, reversed cap, etc...

I suppose you have already check the main PSU.

I have no more suggestions, good luck.
Gianni
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Old 07-31-2008, 06:03 AM   #3
robofind
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Default Re: Compaq Evo D510 SFF - worked 30 minutes after recapp and than stopped.

Gianni you are right.
The CPU Vcore voltage is OK, so the problem is elswhere on the board.
The power supply may have problem too. All its capacitors are Rubycon and look OK.
But the voltages are higher than normal. 5V is 5.8V, 12V is 13.7V.
I will measure all the voltages and will try to see which part of the scheme shuts down.
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