Motherboard repair headache Asrock G41M \ VOGONS

Motherboard repair headache Asrock G41M

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First post, by Nexxen

Posted on 2023-04-01, 16:20

Nexxen Offline

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I got this board. Not powering on, PSU is preventing a short I guess.
I checked ATX power connections and I have a short on +3V and maybe on +5VSB too.
Just plugging the power connector makes the SB turn hot, but not unbearably. No other components get hot.

I have a strange behaviour on the +5VSB and PSON#, where VSB goes to a 20Kohm R, on the other side I have +5V as well, which is wrong.
A site provided many m/b schematics and I tried to identify the issue and my conclusion is that the SB is dead or possibly the NB (stays cold though).

I'm not really looking for help in troubleshooting, more of a general comment on what's happening.
Even with boardview schematics it's till difficult to sort things as beginner 😀
To me it's a donor board from now on because desoldering the SB is too difficult.

Thanks

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Reply 1 of 2, by shevalier

Posted on 2023-04-01, 18:18

shevalier Offline

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i am not familiar with Intel (matherboard) Core 2 era.
But ICH7 (or something like) has no direct powering from Vsb or 3.3V rail. You should find little regulator (LM1117 or equivalent) for 2.5~1.8V from +5V_standbay and powerful mosfet regulator from 3.3V rail to Vcore of South bridge.

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Reply 2 of 2, by Nexxen

Posted on 2023-04-01, 18:28

Nexxen Offline

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Rank: l33t
Posts: 2446
Joined: 2020-03-05, 13:37
Location: Italy

shevalier wrote on 2023-04-01, 18:18:

i am not familiar with Intel (matherboard) Core 2 era.
But ICH7 (or something like) has no direct powering from Vsb or 3.3V rail. You should find little regulator (LM1117 or equivalent) for 2.5~1.8V from +5V_standbay and powerful mosfet regulator from 3.3V rail to Vcore of South bridge.

I found that but even by desoldering both it didn't change.
My guess is that something shorted to GND and until I find it there's gonna be some issue.

I'm not stressing about it, I liked the board as it has a THT socket and not BGA.
Its small form factor. 😀

There's a mosfet that gets 1.75V but has no output.

Thanks for your input, I'll keep it mind in a future fault finding session.

Stay safe 😀

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