dionb wrote on 2020-05-19, 17:01:

It's also missing a MOSFET. Odd, as it's otherwise undamaged as far as I can see, but it's clear there used to be a MOSFET there and there isn't any more. Here's a stock pic of a board with the MOSFET present:
The other two of the same size on my board (next to the ATX connector) are Philips/NXP PHB95N03LT. Would it be the same?
Unless I'm mistaken I used to cycle past the factory that made those on the way to work when this board was made 😜

Do not have that exact board but do not think that would be same MOSFET as the other two, the others are in a switching VRM (the coil gives that away) for the CPU. There is no coil in the circuit near the missing one so most likely a different power Mosfet or even a V Reg (for the DIMMS). One of my boards is similar and has a Lintek LV1084 near the DIMMS (is a variable 5Amp power v.reg chip). Not saying the chips are same but the location and support chips around are similar. Cannot find any good closeups thru Google....

I have both revision A1 and B1.

On my revision A1, that Mosfet is not present, although the solder landings for it are prepared. The IC in the far upper right corner is also not populated.

On the revision B1, the Mosfet element is present:

1PHB
255N03LTA
3PHm 0122 A1

as is the IC next to it (towards the corner):

1Texas Instruments
213DFXXK
3HC74

The two large MOSFETS near the coil and the at the lower end of the serial ports are:

1PHB
28383N03LT
3PHm0109B6

Horun wrote on 2020-05-20, 00:36:

[...]
Do not have that exact board but do not think that would be same MOSFET as the other two, the others are in a switching VRM (the coil gives that away) for the CPU. There is no coil in the circuit near the missing one so most likely a different power Mosfet or even a V Reg (for the DIMMS). One of my boards is similar and has a Lintek LV1084 near the DIMMS (is a variable 5Amp power v.reg chip). Not saying the chips are same but the location and support chips around are similar. Cannot find any good closeups thru Google....

Nope, looked and this was about as good as it got. Thanks anyway.

flupke11 wrote on 2020-05-20, 06:22:

I have both revision A1 and B1. […]
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I have both revision A1 and B1.

On my revision A1, that Mosfet is not present, although the solder landings for it are prepared. The IC in the far upper right corner is also not populated.

On the revision B1, the Mosfet element is present:

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1PHB
255N03LTA
3PHm 0122 A1

as is the IC next to it (towards the corner):

Copy code to clipboard

1Texas Instruments
213DFXXK
3HC74

The two large MOSFETS near the coil and the at the lower end of the serial ports are:

Copy code to clipboard

1PHB
28383N03LT
3PHm0109B6

Thanks. TI IC is also not present on my board, so I suspect that the MOSFET may be missing by design. Still looks like something was there though...

Have now replaced the dead caps and tested, but board dead as a doornail. Will re-flash BIOS tomorrow to see if that was the problem.

Hmm Good luck on re-flash. well the 55N03LTA is a high amperage Mosfet but cannot find any info on the TI 13DFXXK. Is like the chip never was, not even a old link. Very strange.

I think that's a date code or something like that, and the chip is a 74HC74.