Would you replace defective capacitors on 5 yr. old motherboards ?

[Matthew Kane]

Which 1 of the above brand names are made in Japan? And are they solid state capacitor?

All except Teapo originated from Japan and still are but the other 4 have factories in Taiwan and China.

Different capacitors are designed for different purposes. For motherboards, the ones that wears out the fastest are usually the Low-ESR (equivalent series resistance, an important factor in fast drain-charge situations, like decoupling) varieties. They are used to smooth out the PWM (pulse-width modulation) power signals from the MOSFETS (or whatever equivalent they actually use, could be bipolar or just FETS if they are older boards), and thus you really want the lowest ESR for that size of a cap. Higher ESR means that the cap heats up more due to Ohmic heating (like batteries) when subjected to large drain-charge cycles. This tends to wear them out faster.

The circuit is not critical with what type of electrolytic is used. You can use less then stellar FL's and FC's and still get away with a rock solid working recapped mobo. But I agree with the rest using the right capacitor for the right job in the circuit when required.

Not necessarily. If used for decoupling, larger capacitance values are generally fine as long as the ESR is equal or lower.

There is no decoupling in HH's application. You also don't have to match the microfarad rating and voltage needs to be matched or higher (both of which you need to watch out for as get to high in value you will have problems with fitting the physical capacitor into the solder lead spacings due to size). In more carefully designed circuits where AC coupling or filtering comes right off zener diodes or a rectifier bridge dropping 100% greater uf rated cap's compared to the original may put too much stress on the diodes, SMPS and PC psu's fall into this category. For motherboard's no big deal. For audio applications, no big deal sometimes more of a benefit, but that's all subjective.

 

[Fenris_Ulf]

Actually, it is decoupling. Not the DC decoupling of a signal capacitor, but the power decoupling of a bypass capacitor.

In my experience the caps that fail on motherboards are the ones that are subjected to the highest heat and load. Those are usually the power regulators for the CPU. In that application, oversizing the caps is fine and doesn't hurt to give them a higher voltage rating. Also in that application, lower ESR is better (in some applications high ESR can be good for dampening, but not here) and the primary limitation is size and cost. Just use one that fits physically (lead spacing, outside diameter, height if that's an issue). You would probably need a cap that is 5-10 times the original value to have an impact on the operation of the circuit and you couldn't physically fit that big of a cap into that space.

 

[tdowning]

Admittedly, I didn't read all of the 3 pages, but IMO,

Do replace caps if:
you're really short on cash.
you have a very specialized situation
^old specialized hardware that only works on Win XP, and you need that old AGP motherboard, because you can't get Win XP drivers for a PCI-Express video-card

don't replace caps if:
you can justify buying a refurbished off-lease dual core system for $200-250 (that's what I see good ones run in the Detroit/SE Michigan area.)

 

[Maxx_Power]

Maxx, some of the info you mentioned reminds me of what I learned back in university. Some other material, such as ESR, I don't recall my professors mentioned it, so either I skip too many lectures or my professors are idiots

I'm going to buy them locally, so I can exchange it easily, some1 told me if I buy a bag, it will be a lot cheaper than $4/capacitor.

I'm just hoping for all the defective that I have in those 2 motherboards, that I can buy 1 bag that has high enough uF to replace all of them.

thanks for the info

You are very welcome. I think you might be able to source some locally. As others have mentioned, it is usually okay to go over the capacitance of the replaced capacitor, but not under (as long as they are close). Ditto for voltage ratings.

 

[Maxx_Power]

The circuit is not critical with what type of electrolytic is used. You can use less then stellar FL's and FC's and still get away with a rock solid working recapped mobo. But I agree with the rest using the right capacitor for the right job in the circuit when required.

I agree, but wanted to comment that this depends on the duty frequency of the switch mode regulators on the motherboard. Higher frequencies -> FM being a better capacitor (I'm not actually sure what the frequencies are these days in a motherboard VRM section, I don't have an oscilloscope at home). FM also has a significantly higher rated life than FCs. So if your board has a lot of heat dissipation around the VRM circuits and the hotter the environment of the capacitors, the more benefit to using FMs (admittedly, newer series are out these days). Other than that, FMs generally measure (with my ESR meter) lower than equivalent Nichicons and Rubycons, but that could be subjective given I haven't measured whole batches of these things. The real kicker is that FMs are super cheap, say from Digikey or Mouser or Newark. When I stocked up on some capacitors, I chose largely FMs because of the range of capacitances and voltages as well as size made the call for me. FCs were often larger (due to design) per voltage and capacitance I needed, but the icing on the cake was the nearly equivalent price of FCs and FMs when ordered in large quantities.

 

[Matthew Kane]

Actually, it is decoupling. Not the DC decoupling of a signal capacitor, but the power decoupling of a bypass capacitor.

Fair enough when I saw decoupling my mind automatically thought audio applications and amplifiers.

Generally most boards would have OK rated ESR and decent ripple rating but low-tier Panasonic solid cap's around crucial VRM areas near the processor, I have not seen any of them fail except the fake solid cap's (which were normal lytic's in a solid cap casing with burst slits on top) on graphics cards fail back in the Geforce 8""" series days.

If it's a good board with blown caps and out of warranty (or you happen to have some lying around) I would go for Oscon's in that area, the newer solid cap casing SEPC in particular. These are very good in digital circuits.

 

[MrCaffeineX]

I've replaced the capacitors on several motherboards (most recently an LGA 775 Dell OEM board) and in several LCD monitors. Cleaning out the old solder took the longest. Setting the new components and re-soldering was quick.

If you can get $20 worth of use out of the parts, why not go for it. If it lasts a few years, you're good. Worst case, you gain some experience in electrical engineering and/or soldering

 

[Maxx_Power]

I want to mention, that ASUS uses AP-CON solid capacitors on their motherboards/GPUs/laptops in large quantities. I think other than their top tier series of boards, everything else uses nearly all AP-CON capacitors. These are Taiwan made capacitors by the APAQ group:

http://www.apaq.com.tw/eng_products_detail.asp?Fkindno=F000001&Skindno=&Pidno=201007130001

and they look like this in red, black/grey also common:

They seem to last as well. There seems to be a bit of avoidance of those caps by others, particularly Gigabyte (not sure about their current gen stuff), but a search on badcaps.net shows that these caps are doing okay so far. Apparently they do fail too, though:

http://forums.anandtech.com/showthread.php?t=2190429

 

[Matthew Kane]

Never seen those type of solid caps on mobos before. Most boards I've seen and owned have Panasonic solid caps with the exception of some server mobo's I have uses Oscons throughout.

 

[dandragonrage]

I've replaced the capacitors on several motherboards (most recently an LGA 775 Dell OEM board) and in several LCD monitors. Cleaning out the old solder took the longest.

It depends a lot on the equipment. I assume you guys don't have a JBC soldering iron like those who might use it a lot (just got one myself, so happy with it) so my advice for doing this job is to cut the capacitors off with flush cutters such as http://www.amazon.com/Xuron-170-II-...id=1395864388&sr=8-2&keywords=diagonal+cutter and then remove the leads.

When soldering to something with large power/ground planes - like a motherboard - lower-quality irons are going to have trouble providing enough thermal capacity. It's easy to destroy the board if you aren't careful. Not saying you personally have this issue, but more as a warning to those who might be looking to do this job for the first time and who might have a very inexpensive iron. Even my Weller WES51 wasn't all THAT good at it.

BTW, as a side-note, the tool to check which capacitors are bad is called an ESR meter. It's been mentioned in the thread by someone else already. If any of you expect to be doing multiple capacitor replacement jobs, definitely get an ESR meter. It's more important than a capacitance meter for this specific purpose.