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820-4924 short on pp5v_s3, 3v3_s5

Y

Yoel Ren

Member
This board came in already messed up by another repair store, i have orange light, i can feel some warm, but not at the cpu, but another part of the board, not at any component, the warm is like inside the board. ppbus_s5_hs_computing is shorted, pp5v_s3 is shorted 5 ohm to ground, pp3v3_s5 is shorted to ground too, i have tried removing q7430 and q7560 which relieved ppbus_s5_hs_computing short

I have tried removing u7501, u7400, u7600 but pp5v_s3 and 3v3_s5 short still present, injecting 3v3_s5 will make u3210 smoking, but removing u3210 will not make the short gone..
 
2informaticos

2informaticos

Administrator
Staff member
PPBUS_G3H went to L7520/60, really bad news.
Post exact ohm values (not diode mode), after removing U7501 and Q7520/60.
For short on 5V side you should suspect C6412/22/32/42 and the controller chips from the other secondary supplies.
Check all Power FETs from page 63.
On 3V3 side you may have the "chance" for bad SMC, or even CPU...
 
2click

2click

Member
I would sujest to first, find the short on PPBUS_S5_HS_COMPUTING, do not inject voltage there, try to find it in Ohms mode, I've read that you should check the big coils first and that will give you an idea according to the values where the short can be. Then you try and fix pp5v_s3 and pp3v3_s5, at least that's what I would do... Hope to help you in some way...
 
Y

Yoel Ren

Member
yeah actually I have inject voltage before, which result in u3210 smoking, and I also feel heat at another part inside the board ( not from the cpu ), maybe the traces is messed up inside the board
I will return this to customer then, thanks..
 
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