effects of bad capacitors

[davexnet]

Hi all, I resoldered in some replacement capacitors about 6 months
ago due to leakage. No stabilty problems now,
but I do get a weird brrrrrp sound when I turn off the PC (1 or 2 seconds
long) .

I'm using the onboard audio and the sound can be heard through the
speakers. My current "solution" is to make sure I turn off the speakers
before I power down the PC. (out of sight, out of mind, or something
like that)

I suspect either something was damaged in the onboard sound HW or
there could be some current leakage somewhere. (My capacitor
replacement not 100% successful)

It's an older MB, socket 939. It doesn't seem to be getting any worse,
and I'm leaning towards getting a cheap PCI sound card to try.

Any thoughts ?

 

[stahlhart]

Replacing the motherboard is not an option? There isn't another Socket 939 board available without the capacitor leakage issue?

You could probably get a Santa Cruz (if there's still driver support from Turtle Beach for your OS) for a couple bucks on eBay, which ought to be sufficient for the troubleshooting, but I'd be real careful about not throwing away good money after bad here.

 

[Harvey]

Hi all, I resoldered in some replacement capacitors about 6 months
ago due to leakage. No stabilty problems now,
but I do get a weird brrrrrp sound when I turn off the PC (1 or 2 seconds
long) .
.
.

I suspect either something was damaged in the onboard sound HW or
there could be some current leakage somewhere. (My capacitor
replacement not 100% successful)

I don't know what you mean by "not 100% successful," but in theory, every part was specified by the designer(s) for a purpose so if you didn't replace all of the caps, this could be the problem. You could also have problems if you didn't use caps with the same high frequency, leakage and temperature characteristics (or better) as the originals.

The biggest problem is that high quality caps are expensive in small quantities so it may be less expensive to buy another known working Socket 939 motherboard.

Hope that helps. Good luck.

P.S. YGPM about regaining access to your original account.

 

[davexnet]

Harvey, thanks for doing the biz on my ID.

The worry I have about my attempt to transplant the capacitors is related to my
poor attempt at soldering.
First of all, my original soldering iron was too low powered and I'm wondering if my
futile attempt to heat the area could have resulted in excessive heat reaching the
board, possibly damaging some of the fine traces.

I had this problem repairing a TV once. The parts came out easily, but
the little traces dissolved at the solder point. I was lucky that I could follow the path
and run a wire to replace the trace.

With the MB, no clear indication because the traces immediately disappear under
the green lacquer and are impossible to follow. The solder point is a tiny circle
around the hole, barely 1 millimeter across.

 

[stahlhart]

I would assume that it's probably a plated-through hole and a multi-layer board also.

 

[Harvey]

Harvey, thanks for doing the biz on my ID.

I would assume that it's probably a plated-through hole and a multi-layer board also.

Which is a major problem when removing and replacing components. You can easily break connections on the internal layers with no visible evidence of the damage on the top and bottom surfaces.

 

[Iron Woode]

Harvey, thanks for doing the biz on my ID.

The worry I have about my attempt to transplant the capacitors is related to my
poor attempt at soldering.
First of all, my original soldering iron was too low powered and I'm wondering if my
futile attempt to heat the area could have resulted in excessive heat reaching the
board, possibly damaging some of the fine traces.

I had this problem repairing a TV once. The parts came out easily, but
the little traces dissolved at the solder point. I was lucky that I could follow the path
and run a wire to replace the trace.

With the MB, no clear indication because the traces immediately disappear under
the green lacquer and are impossible to follow. The solder point is a tiny circle
around the hole, barely 1 millimeter across.

http://www.badcaps.net

has lots of info about repairing a board.

 

[davexnet]

AS I mentioned, the board runs stable, no issues to speak of except the
"brrrp" sound at power-off. It did seem to start after I replaced the caps.

I looked at the advice on badcaps.com and my method was similar to theirs,
once I had a proper soldering iron. Perhaps I'll email them to see if they
think any further tinkering will help.
At this point, obtaining a used socket 939 motherboard may be an option,
or perhaps throw in a cheap sound card to see if it fixes it.

Thanks all for your suggestions.

 

[Xpage]

I was able to find a used 939 board about 18 months ago when I finally got tired of my abit Kn-8, not having 2 SUB ports work on the back, I eventually tossed the board one day, though I should have kept it and ebayed it for $15 or some amount.

You can probably snag one for around $40-60ish is my guess depending ont he board you want

 

[Linflas]

When the caps went in my A7N8X the only sign I saw originally sounds very similar to what you describe. I would shut down the machine and after it powered off it would do a sound like you describe. At first it would last just a couple of seconds but it gradually increased in length to the point where it would do it continuously unless I powered off the power supply. Other than this the machine was rock stable while up and running until one day it refused to power on at all.

 

[davexnet]

Linflas, thanks for that detailed info. I suspect something like will happen to mine
if I leave it alone. Did you ever replace your caps?

I'm concerned that if I do nothing, it might eventually destroy all the add-on cards also.

I've got some extra caps. I guess I could make a second attempt.

 

[Linflas]

Linflas, thanks for that detailed info. I suspect something like will happen to mine
if I leave it alone. Did you ever replace your caps?

I'm concerned that if I do nothing, it might eventually destroy all the add-on cards also.

I've got some extra caps. I guess I could make a second attempt.

Nah, I came across an A7N8X-E at a computer show and bought it from the guy for under $50.00 IIRC. It was also flashing a light on the case while it made the brrp noise, I don't remember whether it was the HD access light or the power light. The day it decided to start doing it all the time my wife happened to be home and called me at work to tell me about the strange noise coming out of my computer room.

 

[davexnet]

I made the second attempt today. I had the box open to replace the CPU HSF and
recalled that I had a 2nd new set of the 5 capacitors sitting in my desk.

I did it a little differently this time. I left the capacitors slightly proud of the board,
enough so that I could attach a heatsink to the legs as I soldered them in.

Problem resolved, no more "brrrrp" sound at power off.
Playing music through the onboard audio actually sounds better than it did before,
a more tighter sound. Perhaps a side effect of the, presumably, cleaner power ?

 

[amorimluc]

Capacitors can be very tricky...

Leakage was already mentioned here, but I second the opinion that it's usually the primary cause for a capacitor malfunction.

In my experience replacing motherboard capacitors I've found these sites useful:

http://www.capacitorlab.com/replacing-motherboard-capacitors-howto/index.htm

http://afrotechmods.com/tutorials/2011/11/28/capacitor-replacement-tutorial/

http://www.motherboardcapacitors.com

 

[Magic Carpet]

IMO, getting a used Sound Blaster Audigy is a good reason to upgrade your sound experience.