Cap fell off ASUS Motherboard

C

culthuu

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I recently bought an ASUS M4A785TD-M EVO off of ebay. This isn’t a practice I usually do but the customer was very specific he wanted this particular AM3 board and it wasn’t available at a reasonable price anywhere else. It arrived quickly and looked good but when I went to put it into the case one of the capacitors fell off. This is a thru hole cap and the leads had pulled out of the rubber base of the body. Looking at the location where the cap came from, I believe it’s part of the power phase array.
The board works without it, boots normally and doesn’t appear to be unstable in any way. But then I haven’t stressed it either. Does anybody out there know if it’s safe to run the board while I try and find a replacement cap. I know I can solder a new one in and the customer is adamant he wants this particular board. But I’m reluctant to turn it over to him without knowing if it’s going to die somewhere down the line. I’d send it back but finding a replacement is iffy and who knows what I might get.
I’ll post some photos of the board hopefully so you can see the original location.


http://oecwsa.sn2.livefilestore.com/y1pHsD-2Vgi466HYeHU-UxiOFd51QS2V-FPgr4KAEPXI67Eb6imrPKXz8yq9L2mclFf5bBj3moG-AutUR4rtnYzBbH1e2ItrmR7/IMG_1052.JPG?psid=1

http://oecwsa.sn2.livefilestore.com/y1ptLO_LXgJKVz9PXwu3dUL5f3pK5RZ72Uxp0-sfWOE-oMhe1M7yJURNk8y26eSdLUHsfXrgOLoMLGGQ3uHFnxWTYhaqvC9qaQB/IMG_1053.JPG?psid=1

http://oecwsa.sn2.livefilestore.com/y1p0ABmf2kZHcI7Uh9XIZ1M2cHMHYbVgbpvItYjMNQiA-oq3grNl0YyERPgDuf7yeLMUbHwruCf0rFOsh3dXXp1FL6ctA4ioNb3/IMG_1057.JPG?psid=1
 
if you have the old board. you could always take one from the old board and put it on the new board. if you dont you could try google to find one. or you could stress it. and stress as much as you can and if it's stable then its stable
 
Well if it is just a filter cap you are probably fine. Generally power rails have more capacitance than they need, for a lot of reasons, so one down would probably be ok. Could it be problems? Sure, as the capacitance in the ones left fades (it does with time) then maybe a problem develops. There is no real way to test or to guarantee.

So, if you are worried, then buy a new cap. A low ESR electrolytic of the same voltage and capacitance rating should do the trick. If not, just leave it be and it'll probably be fine.
 
It does appear to be a filter capacitor for the processor. I would be careful running it too hard. If you do stress it, it could damage something. That part of the voltage regulation is going to have high votage ripple because essentially the filter is no longer within spec (or not functioning at all). I do not know the specifics on that circuit, but if it didnt need voltage regulation it would not have it. Think of it like you lost a chunk of your harmonic balancer or a chunk of crankshaft on your car. It may not be a problem at low RPM, but it could cause the whole engine to come apart at high RPM.

If it were somewhere else I wouldnt have been too worried, but that close to the processor makes me think its the voltage regulation to the CPU which is more sensitive than most components.
 
Just look at the spec of that cap and order one from Ebay or any electronics dealers and unsolder the broken pieces off and solder the new cap on. It's not hard at all...
 
JCNiest5 said:
Just look at the spec of that cap and order one from Ebay or any electronics dealers and unsolder the broken pieces off and solder the new cap on. It's not hard at all...
Click to expand...

undershoot, overshoot, droop, peak to peak and poof there goes a cpu lalala
 
Sycraft said:
Well if it is just a filter cap you are probably fine. Generally power rails have more capacitance than they need, for a lot of reasons, so one down would probably be ok. Could it be problems? Sure, as the capacitance in the ones left fades (it does with time) then maybe a problem develops. There is no real way to test or to guarantee.

So, if you are worried, then buy a new cap. A low ESR electrolytic of the same voltage and capacitance rating should do the trick. If not, just leave it be and it'll probably be fine.
Click to expand...

well what happens when a overshoot occurs? No output cap poof cpu. Caps are there to give the voltage regulator more time to adjust.
 
The filtering circuit around a CPU is designed to smooth out any ripple still there after the PSU has converted AC power to DC. If you have a very good PSU such as the Seasonic X-660 which does less than 10 mV (!!) of ripple on each rail, you don't need much filtering at all. On the other hand if you're powering the system with some more questionable PSU with 80 mV or worse ripple on 12V you bet you want those filtering caps.

Replacing them isn't very hard. Keep capacitance the same, voltage same or (somewhat) higher and use low-ESR caps since the frequency of the signal will be changing rapidly which would heat up high-ESR caps much more. No use in wasting energy and speeding up the demise of the cap.

Good luck :)
 
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