After updating motherboard capacitors, what to do next (Asrock K7VT2, SOLTEK SL-75FRN2L)

[dragon3x]

Hi, I have some 32 bits computer motherboards that need repair, as they fail to
power on.

Here are some examples :

(N.B. "capacitors" indicated here are electrolytic capacitors located in the onboard
switching supply area).
(N.B. #2 : I could not find a 3300 microF aluminum-polymer with a higher voltage
than 6.3 V.)

1 - Motherboard #1 : this is an Asrock K7VT2 (socket A) that still works well. To put it on test
I replaced capacitors with aluminum-polymer.
3300 microF/6.3 V. x 4 replaced by 3300 microF/6.3 V. (KYOCERA AVX)
1500 microF/6.3 V. x 4 replaced by 1500 microF/16 V. (Chinsan (Elite))
***Result : Still works well, as before. This seems to validate the new caps as installed
on the motherboard.

2 - Motherboard #2 : this is an Asrock K7VT2 (socket A) that doesn't POST or work. CPU fan
is running, heat comes from CPU and chipset.
Capacitors were replaced by aluminum-polymer.
3300 microF/6.3 V. x 4 replaced by 3300 microF/6.3 V. (KYOCERA AVX)
1500 microF/6.3 V. x 4 replaced by 1500 microF/16 V. (Chinsan (Elite))
***Result : No better. Doesn't POST or work. CPU fan is running, heat comes from
CPU and chipset.

3 - Motherboard #3 : this is a SOLTEK SL-75FRN2L (socket A) that I wanted recently
to put on test. It POSTed fine and ran for about an hour then stopped by itself.
There was no way to make it POST anymore so I replaced capacitors with
aluminum-polymer.
3300 microF/6.3 V. x 5 replaced by 3300 microF/6.3 V. (KYOCERA AVX)
1500 microF/6.3 V. x 4 replaced by 1500 microF/16 V. (Chinsan (Elite))
***Result : No better. Doesn't POST or work. CPU fan is running for 1 second
then stops.

Now what to do ? Continue with caps ? Next step seems to be 1000 microF on
these motherboards. By the way I checked on either side of these with a
magnifying glass and no damage could be detected.
Besides caps, what can go wrong ? Also what is the likelyhood it can happen ?

There seems to be what could be called "generic" or "standard" motherboard
failures :
1 - One Shot failure: On power on the CPU fan runs for one second, then nothing else
2 - Indefinite failure: On power on the CPU fan starts and heat is produced by CPU
and other chips, as a normal motherboard. However thre is no POST, monitor
stays black and that state remains indefinitely

The present topic contains discussions and advice about these seemingly
eternal problems with motherboards and as such could be merged with
some equivalent topic, i.e. what and how to test, what is important and
what is not, how to repair, which parts are needed ..... lets make this topic
constructive and useful, with real, definitive solutions for the average user.
I thank people for their patience,

[chaos-theory]

I have an asrock z97x with the same symptoms, especially when cold, it doesn't post, sometimes it posts then shuts down then restarts, I keep playing around with flashing bios and checking voltage, I still couldn't find the missing voltage, I checked most voltages and they are normal, this is your next step, check all the rails and voltages with a multimeter, there are posts here about that, there is also a post I made check it, download a boardview and start checking.
For me, I don't know what's my next step, but when mine starts it works the whole day without a problem, I even tried stress tests many times.
You should also check for bent CPU pins, or lowered pins, that happens a lot, if the CPU is getting hot, like really hot quickly then it's fetching something, probably the first bios memory address and reading it, then either boot looping or communication problems, if it gets only warm then it's only idling, not fetching anything, I realised this by trial and error, try switching bioses, take the bios off take the power plug off and press the power button waitz then replace the bios and boot, sometimes it works, this is all I learned, except for some other technical stuff that needs a book to write. Badcaps isn't as alive when it comes to motherboard than it used to be, most people are either tired of helping or don't have time or they think you're not worth it, so yea mate

[stj]

very small caps are used by the syscon chip to handle standby/run etc - dont overlook tiny smd electrolytics.
you can sometimes test this by heating them with a hairdryer and seeing if the board starts

what are these Elite and AVX caps?
i dont think either company makes caps suitable for this job.

[dragon3x]

Re: After updating motherboard capacitors, what to do next (Asrock K7VT2, SOLTEK SL-75FRN2L)

Hi, thanks for these replies.

what are these Elite and AVX caps?
i dont think either company makes caps suitable for this job.

The new alum-polymer caps have been bought at DigiKey (Minnesota, USA). 3300 microF/6.3 V. are made by KYOCERA (AVX series),
a well known japanese company. 1500 microF/16 V. come from Chinsan (Elite brand), a taiwanese company. I have no reason
to believe they are bad or medium quality. Both have an ESR in the 10 milliOhms range, this is the criteria why I choose them.
As a test I installed the caps on a perfectly working motherboard (replacing original, stock ones) and it still works fine
(see Motherboard #1 in my post)

I checked most voltages and they are normal, this is your next step, check all the rails and voltages with a multimeter, there are posts here about that, there is also a post I made check it, download a boardview and start checking.
For me, I don't know what's my next step, but when mine starts it works the whole day without a problem, I even tried stress tests many times.

I would be so easier for me if I had the item number of these posts (i.e. topic number) about measuring voltages with a multimeter,
so that I could find them from the thousands of post on badcaps. Also that post you made with the boardview, another interesting
and useful post I would need to read.

By the way I just ordered 1000 microF/16 V alum-polymer caps to continue replacing/testing. One day I will find something ......