[SOLVED]820-2936 ppbus_g3h 16v

[BMarden]

Liquid Damaged 820-2936 no green light, no fan spin. I cleaned up corrosion around ISL6259 , LCDS connector, U5400 and Q5300, Q4262 was corroded and replaced from donor board, a few misc caps and resistors replaced due to corrosion (mostly around U5400 and Q5300).

Plugged back in and got Green light and Fan Spin, That means I am done right Louis?

I put the logic board back into chassis and ran ASD which failed with "SMC IO failed" on test Th1H.

I checked PPBUS_G3H and discovered its 12.2V. Reflowed the SMC and now PPBUS_G3H is 16V???

I removed F7040 so I could take some measurements around ISL6259 and MOSFETS without the 16V causing damage, but with F7040 removed PPBUS_G3H is 12.50V

Any thoughts anyone?

Thanks

 

[dukefawks]

Put back F7040 and measure again. 16V will not cause damage on PPBUS. Also check sense resist circuits for ISL6259.

 

[BMarden]

Sense circuits look good bottom R7051 R7052 is 3.4Ohm, from R7021 to R7022 is 21 ohm.

I was measuring around PPBUS MOSFETS and magically PPBUS_G3H went to 12.68, so I hit all the points I was measuring with solder and Re&Re the ISL6259

All is good now ASD passed

Thanks