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820-00165 Won't Turn On

C

CRC2018

Member
Posted this in the wrong section by accident somehow so apologies for that! Reposting here:

Got an 820-00165 here on the bench which is causing some confusion. Green Light is there which turns orange as normal, ppbus present 8.6V.

Visual inspection revealed tiny amount of corrosion around u1930 - pulled this off replaced from a donor board and still no power. Pulled it off again and tried the board without U1930 and getting fan spin and no display (expected).

So i'm in a position now where if U1930 is on the board I get no fan spin, no power up. If U1930 is off then the board attempts to power up but doesn't give display.

Possible dead U1930 maybe? Or am I missing something completely obvious here! There is no corrosion anywhere else on the board that I can see!
 
2informaticos

2informaticos

Administrator
Staff member
Let U1930 on the board.
Be sure to get good solders and check its related components and traces.
Check if board turns on in SMC bypass mode.
You can also try removing Q8150.
 
C

CRC2018

Member
Checked U1930 again - replaced it again from another donor board and behavior is the same. With it out i'm getting ALL_SYS_PWRGD, PM_SLP_S3_L and all S0 voltages. With it there get a small pulse on ALL_SYS_PWRGD and then the board reverts and stays in S5 state.

Board does absolutely nothing in SMC Bypass Mode
 
C

CRC2018

Member
Did a bit more checking - soldered U1930 upside down with jumper wires to confirm connections were good and same behavior. Only thing I can think of is there's a CPU issue - it's reading 10ohms to ground on the Phase 1 power rail. Going to pop this one on the unrepairable pile and sell the customer one of my previously repaired boards instead. I do notice the CPU's are more fragile on 820-00165 than they are on 820-3437 is that normal or am I just unlucky?
 
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