Epox KP6-BS

[darklock]

Sorry for the long post, but I want to geive enough information....

Bought a non-working Epox KP6-BS (dual slot 1 board). Upon inspection, all of the 1200uf 6.3V caps were bulging at the #1 CPU slot. The caps at the #2 CPU slot looked fine. Also all of the 1000uf 10V caps by the MOFSETS looked bad also. Tayhem was the manufacturer of all the caps. I replaced all of the caps by the CPU slots (1200uf) , and by the MOFSETS (1000uf)

Unfortunately this did not resolve the issue. I am not 100% sure on how to check the MOFSETS, but I did notice that one of them appear to "open" when using an ohm meter. Input leg to output leg = inifinite resistance. FYI - this particular MOFSET was by the #1 CPU slot. The MOFSETS are still soldered to the board. The other MOFSET by the #2 CPU slot do not exhibit the same behavior while testing with an ohm meter.

Could the bad caps have blown the MOFSET? Any recommendations on where I can get a replacement? I tried to Google the part # D50N03A and nothing of value found. Other markings include K8 5A below the part number & a "M" on the casing. Also, has anyone ever been able to remove one of these from a motherboard? I had tried on a different motherboard in the past, and was never successful.

Thanks in advance.

[kc8adu]

if they read open it is normal.
you may read protection diodes at the gate but thats it.
any with a low resistance between any pin are stuck on or as we would say shorted.

[darklock]

The BIOS was flashed to the latest version using an EPROM programmer, so I know the BIOS is not the issue. When I had CPUs inserted in the slots and measured the output, the MOFSET which appears to be good was putting out 2.8V (Klamath CPU in Slot #2), and the questionable MOFSET was putting out 3.8V (Klamath CPU in Slot #1) --> too much voltage.

Any other ideas on why the board won't POST? Perhaps the some other component is dead?

Thanks again.

[kc8adu]

chipset or processor damage.
fix the vrm issue or you will destroy the cpu's

[bushytails]

you most likely have, at a minimum, a shorted FET. as kc8 said, if you're getting excessive voltage to the cpu, DON'T RUN IT. you'll fry your cpu. it's also possible the northbridge or other components are already dead. unless you want a real project (and have the skills and tools to do one), you might want to just find a new motherboard...

--Randy

[darklock]

chipset or processor damage.
fix the vrm issue or you will destroy the cpu's

Any recommendations on where I can get a replacement VRM? I tried to Google the part # D50N03A and nothing of value found. Other markings include K8 5A below the part number & a "M" on the casing. Also, has anyone ever been able to remove one of these from a motherboard? I had tried on a different motherboard in the past, and was never successful.

Thanks again for the tips.

[kc8adu]

that is a 50a 30v n channel
there are some 2sk types that will work too.

[darklock]

Thanks for the information. I'll give it a shot and post back once I am able to replace them. Might be about a week or so.

[darklock]

Re: Epox KP6-BS

Well, I replaced the MOSFETs and unfortunately the problem is still there. Still getting 3.8V for the output where slot # 1 CPU should be.

Any other ideas of what I can check?

[kc8adu]

Re: Epox KP6-BS

the vrm ic.
follow the gate to it.

[darklock]

Re: Epox KP6-BS

Thanks for the reply. The VRM IC is a LinFinity LX1664CD. Unfortunately the part is obsolete. DigiKey tech rep said that ST Micro L5991AD13TR is an equivalent, but looking at the datasheets for both, the pinouts are different.

Maybe you guys know of an equivalent for the LinFinity part # ?

Cheers.

[darklock]

Re: Epox KP6-BS

Actually, DigiKey carries a replacement for this (LX1663CD-ND) but the lead time is 12 weeks.

Anyone know of another electronics supplier in the US that might have it?

I already checked Mouser, but they don't carry it.

Thanks again.