OT: Failed Capacitors on MB and PSU

craftech schrieb am 23.03.2006 um 15:13 Uhr
This is not a new subject, but since this is the second time for me I thought I would post some information for you.

The motherboard on my editing computer refused to post which is the first sign of blown capacitors. This happened on the computer I am typing this on two years ago and I replaced the blown electrolytic caps. It has been working perfectly ever since.

The average individual tosses the motherboard or the entire computer when this happens which is foolish because it is so easy to replace them if you have reasonable soldering skills. There were a few years worth of motherboards that suffered from poor quality capacitors from Taiwan. And it wasn't just a few companies. It was most of them at one point or another. The bad caps came from Capxcon, Chhsi, Jpcon,Wendell, Jackon, Fuhjyuu, Fuh Yin, Tocon, Stone, Skywell, Raycon, Teapo, Supacon, Tayeh, Yec, Partsnic, JunFu, GSC, G-Luxin, Choyo, CTC, and many others. Newer motherboards have improved in that respect.

Unfortunately power supplies have been rife with bad caps for several years and for PSUs the problem is getting worse instead of better. And it is not just low grade PSUs like Deer. Antec has had a notoriously high failure rate even in their "True Power" series because of mainly Fuhjyuu and Teapo caps.

It is very easy to tell if a cap is blown by looking at the top of the elctrolytic cap at the vent which looks like a cross. Bad caps are bulged (domed) often with brown ooze coming out of them.

They should be replaced with low-Esr caps of which the Panasonic FC and FM caps seem most readily available. The height is what will be different on most of them. The diameter should be matched exactly so they go into the holes in the PCB easily. The blown caps are usually 8mm or 10mm in diameter, but the 11.5mm height of many of them will have to be substituted with 16-20mm caps because that is what is most readily available in low-Esr capacitors.
Most of the bad caps are 6.3v, but 10v is often a better substitute. You can go as high as 16 volts without a problem. Just don't change the actual capacitance value unless you know what you are doing. You have to make sure the longer caps won't interfere with anything. Most of the time it won't and you can lay caps down on their side if there is room by bending the wires at right angles.

Here are the low-Esr caps which are reliable and the last listed have the VERY lowest ESR (not absolutely necessary to choose the very lowest by the way).

Panasonic FC and FM
Nichicon HV, HM, HN, HZ
Rubycon ZL, ZLG, MCZ
Sanyo WX, WG
United Chemicon KZE, KZH, KZG, KZJ

All are Japanese.

As I said the Panasonic FC and FM are the easiest to find in the sizes you may need. I replaced the two that were blown on my editing computer with Panasonic FM caps that I bought at Digikey.

Not to scare you but you do have to be careful when removing them because motherboards have up to six layers with copper traces on each layer. The components are soldered inside a tiny tube whose edges touch the copper on the different layers. The tube must not be disturbed or rotated when you unsolder the cap (usually happens from overheating). Soldering in the replacement is a piece of cake (they DO have a polarity though which is plainly marked).

If you need help with this at any time feel free to e-mail me or post it on the forums.

Regards,
John

Kommentare

johnmeyer schrieb am 23.03.2006 um 15:30 Uhr
There were definitely some bad capacitors awhile back. Another problem is that some manufacturers don't use the low ESR caps in switching power supplies. They are absolutely required there because the series resistance (the SR in the above acronym) will cause the capacitor to heat up and eventually dry out.

All that said, the switching power supply -- which is one of the most marvelous advances in modern equipment, allowing products to be built without those incredibly heavy and expensive power transformers -- are also extremely hard on their internal components, especially since so many products that use them, like computers and VCRs, are left on all the time. There is no solution to the problem, since it is impossible to know ahead of time whether the manufacturer has used high quality capacitors. However, when you replace them, you can usually create something that will last longer than you will, if you use the components that John recommends.

I even preemptively replaced all the caps in the power supply of my industrial strength Panasonic VCR after I lost the battle with my old Panasonic AG-1830 and didn't want to lose another one.

When working on big capacitors, just remember to take a 10 ohm resistor and short them out before working on them. If they truly are damaged, there is no hazard, but if the darn thing is still good, it can still hold quite a wallop. Even the little ones will give you a jolt that makes a bee sting feel good by comparison.

plasmavideo schrieb am 23.03.2006 um 15:41 Uhr
Excellent post, John. I find that bad caps are 95% of the problems we encounter in our tech shop on most all pieces of equipment. I just repaired 2 LCD monitors by replacing electrolytics. I always use low ESR hi temp (105 degree) caps fro replacements, and they last much longer than the originals. Normally, if I have time, I will replace all of the power supply electrolytics as a precaution.

Another point of failure is the tiny .1uf bypass caps usually used across a power rail for RFI suppresion. They will change value or short and load the power supply down.

Another failure point that is now really showing up is the small surface mount electrolytics used on camera and VTR circuit boards. Our DVCPro machines have been notorious for these type of cap failures. As most of our machines are from the same general timeframe I'm assuming that there was a run of bad caps. Some of the newer ones don't seem to have the problem.

While I'm on the topic, I want to encourage everyone not to dump old computers in the dumpster. As the old saying goes, one man's trash is another man's treasure. I've been able to take pieces/parts and make up perfectly good working systems from "junk" (to some people that's anything more than 6 months old) and donate them to various places or needy families. Look for a computer recycler in your area. Most will take your stuff for free and do something useful with what they can, and properly dispose of the rest at no, or modest, cost to you (sometimes they charge 5 or 10 bucks disposal fee for dead monitors). Non-profits and families that need only word processing, internet and email and accounting software are grateful to get PIII 450 machines all day long - something that for editing is ancient crud to us. I just arranged with a recycling company to get 2 PIII laptops for a non-profit I'm on the board of, and everyone is happy, including the landfill.

Nuff of the soapbox, now back to reality which is already in progress.

Tom
riredale schrieb am 23.03.2006 um 15:49 Uhr
You can do a Google search on "motherboard capacitor replacement" and get lots of useful info about how to do this yourself. Personally, I would only recommend this for the kind of person who has worked with soldering irons in the past (remember the old Heathkits? Are they still around?).

An alternative solution is to just buy another motherboard on eBay. I did this when my board died around Christmas; I found an identical board via eBay for about $21 + $8 shipping. Just unplug everything, swap the boards, and plug everything back in. On many boards the bios is on a chip that can also be swapped. Presto!--back in business.
Coursedesign schrieb am 23.03.2006 um 15:50 Uhr
It is also outright illegal to dump computers, printers, etc. in household trash in many locales.

These contain large amounts of toxic chemicals that can seep out of landfills and destroy groundwater supplies.

Gotta get it to a specialized recycler, they really take care of every part. It's like the cattlemen using "everything except the moo."
plasmavideo schrieb am 23.03.2006 um 15:55 Uhr
"remember the old Heathkits?"

Used to build those for my ham radio stuff. You can still find them around on ebay. I saw a listing several months ago for one of their ham transceiver kits from the mid 70s STILL UNASSEMBLED IN ORIGINAL BOX. If I had lots of spare time, I might have tried to pick it up just for old time sake.
johnmeyer schrieb am 23.03.2006 um 16:07 Uhr
And don't forget to NOT dump Ni-Cad batteries, possibly the most toxic item in your house. Our local recycling makes no provision for batteries, which absolutely astounds me. Cadmium is really nasty stuff.
craftech schrieb am 23.03.2006 um 16:19 Uhr
An alternative solution is to just buy another motherboard on eBay. I did this when my board died around Christmas; I found an identical board via eBay for about $21 + $8 shipping. Just unplug everything, swap the boards, and plug everything back in. On many boards the bios is on a chip that can also be swapped. Presto!--back in business.
============
Not a bad idea, but how about this?
While the new motherboard got you up and running fast it still has the same capacitors on it that will also probably fail at some point (if that's what is wrong with the old one).
Replace any blown caps on the old one and when and if the new one goes you will have an instant replacement.

John
JJKizak schrieb am 23.03.2006 um 16:29 Uhr
I sort of question the use of a given motherboard for over two years or three years unless it is used for "E" mails. Just get a new one and be 5 times more current, more speed, more capabilities, more usefull USB & Firewire jacks, wireless, dual core support, 64 bit support, etc.
That's why they put the "last for two year" caps on in the first place. Not everybody builds Supermicro boards. The upgrading will never stop---"HDV editing"---"3D HDV editing"---"holographic editing"---3D HDV Holographic editing---"3D Holographic 4K editing"---"3D Holographic 100K editing"--- and so on and so on. Power supplies are a different story.

JJK
bw schrieb am 24.03.2006 um 06:40 Uhr
Lots of small appliances are going to be dumped because of uneconomical professional repair. The prime cause will be faulty or dried out caps in the power supplies. Almost all power supplies now are switchmode with dozens of critical electros. If you're not a tech' cultivate a friend who is. Some times one 20c cap will fix it!!
Brian
johnmeyer schrieb am 24.03.2006 um 15:44 Uhr
I sort of question the use of a given motherboard for over two years or three years unless it is used for "E" mails.

I see your point, but the vast majority of computer use is nothing more than web surfing, email, word processing, and spreadsheet. The speed increases of the past decade make very little difference for users of these applications.

I still have an ancient 486 running Win 3.11 and it works just fine for that, although I'll admit that this is not the ideal computer. However, I also have three computers running Win95 and Win98, and they get used all the time, with absolutely no problems or complaints. I never feel like I am compromising when I go back and use them, although I also have a laptop using Win98 that has one of the earliest Pentiums, and it is actually pretty slow when surfing the web, so in that case, it is not so hot.

Most users who only do these few things with their computer upgrade not to get a faster computer but because they've gotten some sort of adware or virus and can't get rid of it. I can't tell you how many people I talk to that talk about how their old computer "slowed down" and they figure it was time for a new one. If I were a conspiracy kind of guy, I'd think all the adware and viruses were done by the computer makers themselves, and that Microsoft's inept response to the threat was intentional, since it has clearly helped their bottom line.
JJKizak schrieb am 24.03.2006 um 16:52 Uhr
Windows 3.1, oooh yes, now I remember, the last operating system I understood.

JJK
Coursedesign schrieb am 24.03.2006 um 16:58 Uhr
Best Buy has some kind of battery recycling program wonder if they take NiCads?

Every POS razor, Dustbuster, cordless phone, etc. has one of these batteries (unless it's really new), and of course they go bad pretty quickly.

plasmavideo schrieb am 24.03.2006 um 17:23 Uhr
John,

That's my point. Most of the computers that I've rebuilt and passed on are to either people who have never had a computer, or to non-profits that just need basic WP, Database and email functions. For them, W98 and a Pentium 266 MMX is just fine.

I still have a AMD K6 233 running W98 that runs all of my ham radio software and radio interconnects just great, plus I can boot into pure DOS whenever I need to.
johnmeyer schrieb am 24.03.2006 um 18:18 Uhr
Every POS razor, Dustbuster, cordless phone, etc. has one of these batteries (unless it's really new), and of course they go bad pretty quickly.

You are exactly right. And they all get thrown into the dump. I'm not the "greenest" guy around by a long shot, but of all the things we as individuals put into the trash, these are ten times worse than just about anything else I can think of.

I rebuild all my gadgets when the batteries go, usually replacing the old NiCads with NiMh, which are a LOT greener, and usually have a huge increment in capacity. My old 1975 HP-67 calculator runs all day on NiMh, compared to just 2.5 hours on its original batteries.