820-2915 PPBUS internal short?

Kyle93

Active member
Have a 820-2915 with green light but no fan spin. PPBUS has fluctuated between 12.25 and 12.59V

Replace U7000 and R7005 but still have same issue. Noticed I have short on PPBUS_G3H. When R5400 is removed the short is gone. I have replaced R5400 two times now and each time it is replaced, the short returns.

Does this board sound like it has a short in the board itself at this point?
 

2informaticos

Administrator
Staff member
"PPBUS has fluctuated between 12.25 and 12.59V"
Impossible if PPBUS is shorted to ground.
You done something wrong and has been shorted after that measurment maybe...

Probably short on the CPU power supply.
Compare short value to ground (ohm scale) with the value on CPU coils.
Next, check resistance between PPBUS_G3H and the big coils.

Do NOT inject voltage on PPBUS_G3H before all high-side MOSFETs are checked!!!
 
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