PS3 Super Slim 4002C no power and keeps blowing up MOSFET after replacing

[feng_ye]

I came across a 4002C motherboard NPX-001 that turns it self off immediately with no red light. It appears to be having shorts on 12V power rail so I found a mosfet on RSX power rail is short so I replaced it with a donor board's mosfet, in the same place. Assembled and turned on, for the first 3 seconds it even display pictures but again turned it off with no red light again.

Took apart and checked again, the replaced mosfet is shorted too. Checked the PSU and it outputs 12V properly without too much ripples. So I was wondering could be the other mosfet causing the problem, or could it be the switching controller IC? Also it appears in this NPX-001 there's only one set of mosfets that does RSX's power but two sets for the Cell.

I also checked the resistence of the RSX VDDC it appears to be quite high (27.4Ohm rather than single digit like in Phats). Could it be the RSX is faulty? It does show the screen before the blowing up the replaced mosfet though.

 

[feng_ye]

Reference picture


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[vyktormvmpay25]

That side of rsx replace both mosfet and that tiny cap in parallel with line 01 uf.
Also after remove both mosfet check main line with blue if you see low resistance like 10 ohms one of electrolitic may be defective or those ceramic caps of 22 uf.
Mostfets are pair of that side they work in tandem

https://s.go.ro/e6f5wnyh
Won't let me upload photo so is on link

 

[feng_ye]

That side of rsx replace both mosfet and that tiny cap in parallel with line 01 uf.
Also after remove both mosfet check main line with blue if you see low resistance like 10 ohms one of electrolitic may be defective or those ceramic caps of 22 uf.
Mostfets are pair of that side they work in tandem

https://s.go.ro/e6f5wnyh
Won't let me upload photo so is on link

Pretty sure those MLCC or electrolytics are not shorted. The problem is I cannot figure out why the replaced mosfet get blown up. Checked the datasheet and there should be no way so easily, otherwise the current will above the PSU's limit and given the PSU outputs proper 12V.

Any chance because of RSX's resistance(~30Ohm) is far off?

Thanks for your advice, I'll try your trick when I get time.

 

[vyktormvmpay25]

Rsx 28nm min values 26ohm max value 35or 37 ohms so rsx is fine in range, you got image for few seconds if I read correct? so rsx is fine.
Now there is one dodgy cap or ripple not controlled well, can't remember which ic is controller for those but look there to one lose resistance or dodgy ic controller or a dodgy cap for that circuit

 

[feng_ye]

Not been able to work on the board but here is the controller ic i believe ISL6332ADRZ

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[feng_ye]

Update: today I tried to replace the high and low mosfets together. I also sprayed thin rosin on the surface to see potential heat up/shorts. Turns out it's working! Maybe last time the mosfet i used was also faulty, though I did check before soldering. Anyway, thank you for the help!

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