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This instructable will show you how to diagnose and repair bad capacitors on computer circuitry saving you money on new appliances and preventing landfills from filling up.
WARNING RISK OF ELECTRICAL SHOCK CONTINUE AT YOUR OWN RISK
Always unplug electronic devices before opening them! Even after opening make shore you discharge all the capacitors with a discharge rod.
WARNING RISK OF ELECTRICAL SHOCK CONTINUE AT YOUR OWN RISK
Always unplug electronic devices before opening them! Even after opening make shore you discharge all the capacitors with a discharge rod.
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Signing UpStep 1Materials
You will need.
a Soldering iron
a cutting pliers
gloves
safety glasses
rosin core solder
the replacement capacitors
an anti static band (if your working with delicate circuitry)
a de soldering pump (optional)
and de soldering wick (optional)
a Soldering iron
a cutting pliers
gloves
safety glasses
rosin core solder
the replacement capacitors
an anti static band (if your working with delicate circuitry)
a de soldering pump (optional)
and de soldering wick (optional)
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By mixing new with older capacitors in a parallel bank, the newer capacitors will take more than their fair share of the load as the old capacitors have higher ESR.
Many years ago I did some research on these capacitors. It turns out some companies had stolen some designs from a Japanese manufacturer and left out some of the chemical formula. So millions of these were put into products.
Safety: All though not a major concern, motherboards can be subject to static electricity damage. So try to ground yourself to earth ground especially when working on carpet. In the U.S. all those screws in between the AC sockets are tied to earth ground.
The author is correct that polarity is very important. The little grey stripes indicate the negative side. And higher voltage ratings doesn't matter. The voltage rating is just the maximum voltage that can be applied to the component.
And the author is also correct that shape and size don't matter as long as you can get it to fit and soldered.
I've read this also, but it does not make sense.
Would an established capacitor maker, with their own magic brew just take another formula without testing? It just does not make sense.
Purchasers for the motherboards, printers, etc., looked for the best price. They may have done some internal testing but, in this case, the major failures were often years down the road. I worked in the electronic reliability testing for many years and know the difficulties of finding long term failures in a short period of time. (Manufacturers can't test a product for 10-15 years before they sell it as it would be obsolete)
As a retiree, I buy a lot of my electronics on ebay, mostly from China. Most of it has been fairly good quality but I have had some bad, especially cables, audio and USB. But when I spend a $1 or $2 for a cable, I don't expect a lot.
As for long term reliability, I have even less expectations, but then I am old.
LOG
There is also accelerated aging (at high temperatures) to try and gauge future failures.
You are probably more familiar with the current state of electronic manufacturing but I suspect that 99% of electronics is manufactured overseas. Though much is probably outsourced by established companies, there is still issues of transfer of technology and quality control.
My experience was in testing products rather than components. Heat was the primary gauge but we also used cold, high/low humidity and vibration in all axis. Another method we uses was reliability software where you input a bill of materials and estimated weakest components based on reliability data from the component manufacturers (primarily MTBF).
In my experience, I almost never see an electronic component failure unless it was subject to static or lightning. Most of the failures I've seen are mechanical, especially fans and connectors.
LOG
Most motherboards are powered by 5Vdc and 12Vdc which should be well buffered by the power supply. In my opinion, if capacitors on the motherboard were damaged by power surge problem, then the power supply would be completely fried.
LOG
* I have had some equipment last a long time, possibly because of the surge protectors
* The surge would be seen mainly on the high voltage side of the power supply
http://www.macrumors.com/2011/09/13/intel-previews-low-power-haswell-processors-for-2013/
Given that computers are said to consume more energy than air travel, this might not be a bad thing at all.
These capacitors are electrolytic capacitors used to filter DC power. Current doesn't actually pass through them. That is why they only have a voltage rating and a value. So in a higher powered circuit an electrolytic capacitor may not filter as well but it wouldn't contribute to a higher capacitor failure rate.
There is a trend to low power consumption. IMHO, this is due to lower CPU voltages and multiple cores. Multiple cores generally run at lower speeds (less power) but higher performance (because of multi-cores and other design advancements.
By the way, I just ran across an interesting but somewhat biased website:
www.badcaps.net
LOG
So I must differ with you on this, the higher the power of the circuit, the higher the heating of the capacitor and so the faster it fails.
Now I agree that electrolytic capacitors in an analog circuit can pass current. And this is important especially in AC motor circuits.
So I would like to see any digital computer circuitry that has electrolytic capacitors that pass much current and heat up.
LOG
First, I was wrong about electrolytic capacitors not heating up in operation. They do.
"Ripple current is the rms value of alternating current flowing through a capacitor." This means it's AC current not DC so higher steady currents don't affect it.
Second, I believe ripple current is more of an effect of input variations than output. But output AC loading will affect it. Higher powered systems are usually running at higher frequencies which could increase ripple current so you may be right about them generating more heat. Another factor is higher powered CPUs generate more heat which will likely raise the ambient temperature of the motherboard which will also raise the temperature of the capacitors.
Third, I think the main reason designers use capacitors with lower ESR is that lower ESRs improve their filtering capabilities.
Full disclosure: I am speaking more in practical terms (technician) than in theoretical terms (engineer) as I do not have an engineering degree.
So have you seen/heard of more capacitor failures in higher powered systems? Personally, speaking, I haven't seen any electrolytic capacitor failures except when I put one in backwards. In my opinion, if a motherboard is properly designed, you should see minimal failures of all components including capacitors. The only significant motherboard capacitors failures I've heard of, seem to be because of the 'bad' caps.
LOG
In is my theory that the slew of failures was not so much due to industrial espionage as the increasing demands of high power CPUs and that designs then caught up with this by using the new solid-state capacitor technology.
All this said after the need to recap the mother-board of a G5 iMac a couple of weeks back. I used electrolytic capacitors, and now wonder if perhaps I should have moved to solid-state types.
Perhaps there was a bad run years back, but for me it doesn't make sense; the well established manufacturers would surely not have use an untested stolen recipe when they had their own. Hence the theory of higher power CPUs as resistive heating goes like I^2, so just doubling the speed of a chip would increase heating by a factor of 4.
I recapped the power supplies on these machines a few years back, but one of the capacitors was not low ESR, and this failed after only 2 years; so I think low ESR is important for life.
http://en.wikipedia.org/wiki/Capacitor_plague
Your concepts may certainly have contributed to capacitor failures but how would you explain:
1 Flawed capacitors first appeared in 1996, long before high powered computers.
2. Failures in compact fluorescent lamp ballasts, LCD monitors
Here is another quote from http://en.wikipedia.org/wiki/Nichicon
"In the early 2000s, Nichicon is known to have produced and sold bad capacitors to major computer manufacturers, including Dell, Hewlett-Packard, and Apple. Nichicon's capacitors were prone to pop and leak fluid, causing computer failure."
I am very aware that you can't believe everything that appears on the internet but I do believe these.
Anyway, you may have an opportunity to test your theory, if your G5 iMac fails again with the replaced capacitors.
By the way, I agree that low ESR capacitors are important in power supplies. You should also check the maximum operating temperature of the capacitors as many power supplies run pretty hot. Several articles said that power supply capacitors may get 10-15 degrees Celsius hotter than ambient.
LOG
I should have more detail soon when I can use an ESR meter on those capacitors I removed by looked physically sound.
I went with the Peak Atlas ESR-70 ($130) although the Bob Parker ESR kit ($70) also looks nice.
While such meters can measure capacitors while still in circuit, they may not be very useful for parallel banks, as the good units will give rise to a low ESR reading.
One thing you might want to try is see if any are running particularly hot, which might also spell impending failure.
I also find working on a mother board somewhat risky, so would prefer to keep the number of times I work on it to a minimum.
Anyhow, glad to learn your fix is holding up for you.
those capacitors were not repaired, they were replaced... (board was repaired)
;-P
I needed 50uF and I had 100's
So I soldered them in series and put the leads in, lol.
The final board looked like huge electrolytic caps sticking out, so unprofessional, but it worked.
Some other key specifications to look for in your replacement caps (other than the capacitance and voltage rating) is the Diameter, Lead Spacing and Body Height of the caps, which is usually given in millimeters (mm). Some mobo's don't have much space or vertical clearance available, so getting an exact match can be pretty important.
Once you have these physical measurements (as well as the μF and V) you'll be able to search the web more accurately for the exact parts. There are a lot of eBay stores out there selling kits too, or check out Futurlec (http://futurlec.com/CapElectro.shtml) for pretty cheap capacitors - they also provide all the sizing specifications.
*and* you can re-route the larger caps a few mm or cm here or there with longer leads -- thats how ben heck makes the xbox 360 laptop, by laying all the caps flat and lengthening the leads.