[SOLVED]820-4924 R7020 on fire no matter what.

JohnB8812

New member
Ok so I'm stumped, and I'm sure it may be something dumb I'm overlooking, but this board came in with liquid around the SMC, clock chip, and a backlight chip. Cleaned areas of corrosion no problem nothing concerned me that much. Currently getting no light on the charger and R7020 is on fire. I removed it and the diode to 3v42 to check for a short on input. I got no short but said what the hell and replaced the 3 input caps and 3v42 regulator to be safe. R7020 remains on fire. I next thought possibly Q7080 and the ISL could be causing it so removed both and still no change R7020 on fire. What else can be causing this resistor to burn? No short on 3v42 or PPVIN_PP3v42_G3H. No short on PPBUS. I'm out of ideas all help is appreciated.
 

JohnB8812

New member
.29 on L7095 both pins.
Removed diode and put power through the regulator got hot again. Removed now zero amp pull as opposed to .11 amps pulled before. Going to put one more new regulator on and hope for the best.
 

JohnB8812

New member
Also when R7020 is removed, the pads it sits on do not get hot, so I don't think there's an internal short under it.
 

dukefawks

Administrator
Remove clock chip and SMC. They could be overloading the 3V42 rail without causing a short.

Actually inject voltage into 3V42 line first and monitor current draw. SMC or clock getting warm?
 

JohnB8812

New member
Thanks Duke! Will do my guess is that the clock chip will be doing it, but I will let you know when I get to it today
 

JohnB8812

New member
Bad clock chip was the issue. Once it was removed no more R7020 on fire and green light came back. Put the ISL back with a new (donor board because my new spool might be bad) clock chip and all is good! Thanks again Duke!
 
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