[SOLVED]820-2936 ppbus_g3h 16v


New member
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?

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


New member
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