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Bad Capacitors?

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October 27, 2002 3:17:35 AM

After pulling my hair out for a few days working on a friend's machine, I think I may have found the problem. In a quick glance at the board as I removed the CPU for heatsink modifications, I noticed that all of the capacitors near the CPU are slightly rounded at the end. Like the begining of bulging.

Now the system (Athlon 900 Slot A on an Epox KX7A board) is displaying all the signs of having too small of a power supply. It freezes in startup, reboots randomly, ect. MBM monitor shows teh voltages as being low as well. So I thought this was the problem....

I used a VOM to test the voltage comming from the PSU, Just to make sure MBM was right. I found that even on a load (System booting, running when it wants to) it does not dip below 12, 5, and 3.3.

Now this leaves me to swapping out parts. I even got a hold of a new CPU to try in place of the normal one. Still all my problems remained. Only part that was not swapped was the mobo.

I have heard of this before with some boards, and know that power fluctuations can be horrible to electronics (my buddy's house is bad for this sometimes). So is this a feasible problem? Is there a way to test them? I was just going to tell him to spend $20 on a new slot A mobo I found (in school and broke, might be a while till he upgrades fully).

Im thinking, New mobo, dont look back. Good Idea? or am I barking up the wrong tree?

System:
900 Athlon "Classic" Slot A
320mb PC133 RAM
Epox K-X7A Mobo
Maxtor 10gb HD (formerly WD 6gb, cloned during troubleshooting)
Geforce2 MX400 AGP
Creative 6X DVD
3com NIC
Generic 56k modem
Win XP Pro

You dont have an <b>ANY</b> key? Your keyboard must not be Windows XP certified...

More about : bad capacitors

a b V Motherboard
October 27, 2002 4:00:16 AM

It happens quite frequently. In fact over 90% of my dead boards have been due to bad capacitors. I repair them by the way, I could fix his.

<font color=blue>You're posting in a forum with class. It may be third class, but it's still class!</font color=blue>
October 27, 2002 11:55:25 AM

It's as simple as replacing them right? Ive soldered circuits before, so it would be no problem.

Btw, you know what causes this ?

thanks for the help crash.

You dont have an <b>ANY</b> key? Your keyboard must not be Windows XP certified...
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a b V Motherboard
October 27, 2002 3:23:52 PM

Normally low quality parts cause this. I've found Mouser Electronics carries high quality replacement parts, but in a slightly larger size. The values are exactly the same, but the mean time between failure is much higher, like over 100,000 hours for some parts.

<font color=blue>You're posting in a forum with class. It may be third class, but it's still class!</font color=blue>
October 27, 2002 3:57:50 PM

I'll check later what the specs on them are, but I might be able to get an Asus board for 20 plus shipping. Could be cheaper than replacing all 19 of them.

You dont have an <b>ANY</b> key? Your keyboard must not be Windows XP certified...
a b V Motherboard
October 27, 2002 4:32:43 PM

ALL 19 ARE SWOLLEN? Wow, never seen that except in lightening damage!

<font color=blue>You're posting in a forum with class. It may be third class, but it's still class!</font color=blue>
October 27, 2002 4:53:14 PM

all 19 of em. Now this is in the same house that has gone through 2 tvs in 3 years, and uncounted other electronics devices. Im wondering if the voltage in the house is low, or spiking. I recommended them to put surge protectors on all the outlets, and that is underway now.

now I must add that they are not severly swollen, just swollen a bit. I dont know if that makes a differance, but still all of them are bad.

You dont have an <b>ANY</b> key? Your keyboard must not be Windows XP certified...<P ID="edit"><FONT SIZE=-1><EM>Edited by Lonemagi on 10/27/02 08:55 AM.</EM></FONT></P>
a b V Motherboard
October 27, 2002 9:25:26 PM

Yes, it sounds like spikes are killing things.

<font color=blue>You're posting in a forum with class. It may be third class, but it's still class!</font color=blue>
November 3, 2002 7:40:37 AM

You're talking about SMT caps right? A quick way to tell if a cap might be out is to see if it's shorted. Caps typically short as they go bad, (the obvious exception being when the explode!) whereas resistors usually fail open. Also, if you've got a magnifying glass, check the solder beads on each side of the cap. The solderable part of poor quality caps sometimes seperates from the body and it's sometimes hard to see with te naked eye. Just some tips.

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