comp mainboard repair

Use good grade 2200 uF, 16V, 105C of the same physical dimensions.

I usually get mine from Digikey, but there are many other vendors.

There's nothing special about the caps on motherboards (unless you consider the 105C spec "special").

They usually need to be 'low ESR' types suitable for high frequencies but seeing as you got the replacements from other mobos, that should be just fine. 105C rating simply lasts longer in this kind of use than the more common 85C parts.

Graham

Ideally you want low ESR caps of the same or slightly greater voltage and temp rating. You can't go too high in most cases or they won't physically fit in the space. I fixed a pile of boards with this problem a few years ago, there was a huge rash of faulty capacitors.

Are you sure? Because I thought that the switching regulators on mobos required low-ESR caps, not just any 105C caps, and that was why different model caps were used for the regulator than for bypass, even when all the caps were of the same brand. Also I've seen many mobos with high quality caps in the regulator circuitry, almost always Japanese brands, but lower quality Taiwanese or Chinese caps for bypass, and this included budget brand mobos, like Asrock and ECS (but not ECS' own budget brand, PCchips).

On 9 Apr 2007 02:48:11 -0700, "larry moe 'n curly" put finger to keyboard and composed:

I don't know what the relationship is like today, but soon after their merger, PCChips and ECS sold exactly the same boards under different model names.

- Franc Zabkar

On Sun, 08 Apr 2007 19:31:50 GMT, CJT put finger to keyboard and composed:

Some motherboards use "solid" aluminium electrolytics, eg Sanyo OS-CON. These are claimed to have half the ESR and half the size of equivalent liquid electrolytics.

FWIW, this is what Gigabyte has to say:

- Franc Zabkar

My ECS K7VTA3 v. 8 was identical to a PCChips mobo, except the latter was red, lacked one set of jumper pins, and had soldered jumper wires in place of fuses. And with another design, the ECS version had Chemicon capacitors for the CPU voltage regulator but OST caps everywhere else, while the PCChips version had OST everywhere. IOW PCChips is cheap ECS' even cheaper line of mobos. :(

I'm taking back an ECS P4M800Pro-M mobo made for the Intel Core2 CPU because it doesn't have STR (suspend to RAM). I can't believe that a mobo so new would lack STR.

I have a Soyo retail mobo based on the intel 810i chipset, and it has Taiwan brand capacitors all over it, but the same mobo used by Gateway uses only higher quality Japanese caps, including Sanyo OS-CONs.

On 11 Apr 2007 02:01:39 -0700, "larry moe 'n curly" put finger to keyboard and composed:

FWIW, OST do make solid caps:

Whether PCChips uses them is another matter, though.

While I was on the OST web site, I noticed that the expected lifetimes for capacitors when operated at their rated temperature are surprisingly low:

- Franc Zabkar

I thought they were all flushed from the pipeline by now, but recently I've seen bad ASROCK K7S41GX boards purchased about 2 years ago going bad (one of them on my own computer, but I had sold several others and now they're all going bad). Arrgh.

Dave