CurtPalme.com Home Theater Forum

ecrabb · Posted: Thu Sep 10, 2009 11:07 pm Post subject: Bad caps?

So, is this what it looks like when electrolytic capacitors die? I've always heard you guys talking about bad/leaky caps, but I'd never seen them first-hand.

The specimen in question here is a Lenovo desktop PC of summer '02 vintage - so just over 7 years old. For you techs, I have a couple of questions...

1) What causes this? Age? Heat? Cheap parts? Combination of all of the above?

2) In a PC motherboard, how will these failing caps affect the computer?

It's torn apart because I was looking to see what network chipset was in the machine to make sure the drivers were correct. The computer was blue-screening whenever anybody tried to access a Novell volume in a Save As dialog box. I tried just updating Novell and the network drivers, but Windows wouldn't update to SP3, either so I decided to nuke the install. It's just our audio box, so it only had a few apps on it.

Now, I've reinstalled, Windows is up to date, and so are all drivers. There's only one weird thing... If anything is tapping network resources, the mouse will hesitate/lock up momentarily. This occurs only sometimes, not all the time, and usually if there is any activity in the foreground, like an MSNBC page rendering in the browser or whatever. It happens in both IE and in Firefox, but not as bad in Firefox. Network driver? Bad caps?

I couldn't update the Nvidia driver beyond 2003 vintage, either... The nvidia installer won't install because it says there are no drivers for my hardware, even though I let it detect my video card and pick the driver install itself. I love how in Windows, there are different driver versions listed, depending on where you look - Display adapter properties, Nvidia control panel, Nvidia web site - with no way to correlate the three. Nice. Thanks, Nvidia.

Probably time to retire this machine, I suppose.

SC

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Change those caps!!! the Pc will be fine after. Very Happy

Athanasios

ecrabb · Posted: Thu Sep 10, 2009 11:12 pm Post subject:

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

I know, But i like to fix sh*t for fun Wink

lol

yeah get a new mac Wink

Athanasios

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

wow, those suckers are toasted. Yeah usually heat is what gets them. theyre rated for x number of hours at a given temp. As the temp. goes up beyond that they're life-span drops.

Mark_A_W · Posted: Fri Sep 11, 2009 12:26 am Post subject:

It's not worth fixing.

You can get a new mobo ram and cpu for $200. It's not a $40k CRT projector worth rescuing. It's time for recycling that PC.

Those are part of the motherboard power regulation circuits for the CPU. As they fail the CPU will see more of a ripple in the voltage.

I'd expect it to become unstable.

I have to admit, I haven't heard the name "Novell" since Windows 3.1..

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

mp20748 · Posted: Fri Sep 11, 2009 11:16 am Post subject:

Those caps did not fail. When they swell like that it's either reversed polarity or an over voltage problem. In the case of the circuit those caps are in, they are swelled from over voltage, which is more of a common problem on aged PC boards.

The surrounding caps are really HIGH temperature or HIGH frequency caps which are used in most high quality switching power supplies. So you'll not find "cheap" caps being used there. The high frequency would eat up low quality caps in that circuits in no time.

The cross lines are on the top of the cap to keep it from exploding when operated outside of its voltage range. When over operated, there will be a split where the lines are. Back in the day, the cap would explode under the same conditions.

Replacing the caps would produce the same results, because the problem is not the caps. The buck regulators are no longer regulating the safe voltage into the caps.

It's easier and cheaper to replace the mother board.

Mark_A_W · Posted: Fri Sep 11, 2009 12:56 pm Post subject:

That may well be Mike.

But Mac is right. There was a big scandal about bad caps on mobos a few years back.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Enjoy some reading... Smile

This was posted by MikeEby in the other thread: http://news.cnet.com/PCs-plagued-by-bad-capacitors/2100-1041_3-5942647.html

Another site based on the original problem: http://www.badcaps.net/pages.php?vid=4

ecrabb · Posted: Fri Sep 11, 2009 2:51 pm Post subject:

Thanks, guys... I really like reading the opinions and all the supplemental material - thanks, Mac!

Obviously, these things see pretty high temps sitting right next to the CPU. It was a 24/7 machine most of the time, too - so I'm sure that didn't help in the longevity department.

I think I'll just shelve it, and pick up a newer used box for $150 or whatever. It's a royal pain in the ass to get purchase approvals this time of the year, but we've got some stuff sitting around I can ebay to get the funds for a newer machine. Anybody want a deal on an Exabyte DDS-1 tape drive w/auto-loader? Wink

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beun · Joined: 28 Jun 2006 Posts: 676

I just had this recently on my nieces computer, the caps looked exactly the same as on the photo above. Most were just bulging and one was leaking. I just replaced them with new caps of a higher voltage rating and everything was OK again. It took be barely 15min and maybe $10 in caps.

Mike,

The caps are bulging because of gas pressure buildup, this is either caused by reverse voltage, over voltage, over current, over heating, shoddy design or just plain aging. Replacing them should just fix the issue especially when you do it before anything else had the time to break.

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

its true, all the power supplies in the iMac G5's have a bunch of bad caps that apple found out after they built all the computers, up untill last summer they would replace the power supply for free but the new supply also had the same bad caps. Jim Waraholic http://jimwarholic.com/labels/iMac_G5.php he has kits for replacement caps. I knew of the issue I just ddint know about the espionage thing!! but I think the apple caps were not Nichicons.

Athanasios

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

had to post this pic. Was up late last night working on a Marquee convergence board. It's been stated by some people that "Marquee's can run forever practically and that most of the EL caps will be fine, No need to worry".
This is a sample of what I pulled last night. I'll say it again, these things are not designed to last 15 years

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

ecrabb · Posted: Sun Sep 20, 2009 7:38 pm Post subject:

Wow, dragan - those are nasty. Thanks for posting. Was the machine that convergence board came from still functioning properly? Any idea what the chassis manufacture date was?

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draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

the board is a 1997, so like me, it's "middle aged" by Marquee standards. No idea how many chassis hours but I don't think that matters all that much, this is just a result of being 12 years old. I should save this thread so next time someone asks "why is my convergence drifting?" I can just link to it.

ecrabb · Posted: Sun Sep 20, 2009 10:52 pm Post subject:

1997, eh? Coincidentally, the same year my G70 was manufactured, IIRC. Next time I'm digging around in there, I'll have to pull the convergence board and see how the caps look. Getting old sucks. Wink

SC