New Capper Needs Guidance

[jbonetwo]

This is going to be my first recap and I don't have any formal training in electronics. I've read all the FAQs on here but its a bit overwhelming. It would be great to get some experienced feedback on this particular problem.

I got a brand new ASRock 970 Pro3 R2.0 motherboard. After assembly, there were some strange symptoms:

The board would not POST: no beep codes, no video. If I removed the video card, i got beeps. If i tapped F2 to enter BIOS, I would get into BIOS with video and all. If I discarded changes from there, I would get a very ordinary "Hard Disk Boot Failure".

I managed to rule out everything except a possible short caused by one of the following:
1. One of the rubber feet of the PSU was displaced.
2. There was a screw wedged between the PSU and the case's motherboard tray.
3. A motherboard pillar may have been contacting the board (most probable).

Unfortunately, my diagnostic steps involved powering on the board ~10 times while it was being thus shorted which is probably what killed it- now i get no beeps or anything with nothing but the CPU and Power connected outside the case. Tested with a different CPU and PSU as well.

Now since I'm abroad, the cost of RMA'ing the board is twice the cost of the board itself. So hell yes I'm all for trying to repair it if I can.

A few questions:
1. Do you guys think this particular case is futile?
2. How would I narrow down which components need replacing (there's no visible damage/burns).
3. If i were to guess, I'd replace everything clumped in the picture below which is in the region of the aforementioned motherboard pillar. What would you recommend for the 3x 820uf CB caps and the 93110 560 6FJ cap?
4. What should I do with the unidentifiable rectangular caps(?) next to the sata ports?

[Agent24]

Re: New Capper Needs Guidance

Did you try resetting the BIOS? Use the clearing jumper (motherboard manual will explain where this is) or take the battery out for a few minutes.

After resetting the BIOS, try the machine again in the same configuration you did when it was working. If you don't get beeps or any sign of life after that, yes, maybe you did short something out with a screw or standoff.


The large square items next to the SATA ports are going to be chokes\coils of some kind, not capacitors. Unfortunately replacing random capacitors and other parts is not at all likely to solve your problem if something did get shorted out. It would require a good level of knowledge to find the fault and good soldering skills and tools to fix it.

Aside from very carefully inspecting the entire board on both sides under good lighting to find anything burnt, there is probably not a lot you can do at this stage. Some of the other guys on the forum can assist in finding shorts but it is not an easy task.

[jbonetwo]

Re: New Capper Needs Guidance

yes i have tried a cmos reset- took the battery out for 10 minutes, connected the pwr sw and held it pressed for 60s to drain. no luck.

close inspection of all caps on the board revealed nothing visibly untoward.

ive done a bit of soldering for my bro when he was studying electronics so this doesn't phase me. will be practicing on old dead motherboards before i do the real thing.

i agree finding the faulty cap if any would be better than guessing but i wouldn't know what reading to expect from a good/bad cap with a multimeter. would a pci post card be able to help diagnose such problems?

[Agent24]

Re: New Capper Needs Guidance

It is unlikely you have a faulty capacitor in this situation, more likely is a burnt PCB trace or damaged semiconductor(s).

I suggest you post your problem in the motherboard section of the forum and ask for help on trying to locate the damage.

Trying to find a schematic of the board would also be a good idea if you want to proceed with troubleshooting at the component level.

[jbonetwo]

Re: New Capper Needs Guidance

several of the smaller caps on the board around the pci-ex slot are giving a 0 reading with the ohm function of my multimeter. does this suggest bad caps? tiny caps on a different board always seem to give me a reading. these ones are 100uf 16v (or 1.6v) caps.

it seems impossible to find schematic for this board unfortunately.

[Agent24]

Re: New Capper Needs Guidance

It depends on what 0 means on your multimeter. Is it the same reading you get when you short the probes together?

Measuring capacitors (especially with a multimeter) in-circuit will not usually get you any reliable readings, however. You need to know if anything is in parallel with the capacitor that could throw off the readings. That is where a schematic would come in handy.

[jbonetwo]

Re: New Capper Needs Guidance

yes it is the same as shorting the probes. these particular caps appear to charge for a split second and then give out a constant zero and will not charge again.

it is the bottom left cap in picture 1 (above the pci-ex slot) and the bottom 2 caps in picture 2 (below the pci-ex slot).



it makes a little sense with the initial no video issue and the way the card sits uncomfortably on the pci-ex slot. I had to prop it up quite a bit to align it to the card holder screws.

i really do appreciate all your help!

[Agent24]

Re: New Capper Needs Guidance

Yes, you should see a charging effect. Try reversing the probes after that happens and see if it does the same thing to discharge.

If the card has trouble fitting in the slot, check the motherboard standoffs on your case are the right height. There are several different styles and some are much shorter than others.

[jbonetwo]

Re: New Capper Needs Guidance

it will charge for a split second the first time. after that it will not charge if i reattach the probes the same way or if i reverse the probes.

the standoffs are fine. only have the ones i need for this board and theyre all the same height and nicely tightened with nose pliers. its just one of those boards where the pci-ex slot is slightly lower on one end than it should be.

got a capacitance meter and a post analyzer card in the mail to look into this. will be about a week.