[SOLVED]820-3536 No SMC_BC_ACOK

[bjf]

I have 4V on CHGR_ACIN and both U7100 voltage sense circuits are measuring fine. SMC_BC_ACOK is measuring about 0.05V. I replaced a missing C7120 and replaced U7100. I've measured all the resistors around U7100 and they are measuring fine. Usually just taking care of the basics will get this solved. Not sure what else I need to get this going. Areas of minor corrosion can be seen in pics.

 

[dukefawks]

Check voltage on R7105 and resistance to GND on ACOK.

 

[bjf]

Around 205kΩ (measured before turning it on). 0.521 drop to ground. Voltage on R7105 is 16.5V on both sides.

 

[dukefawks]

Check R5187, if that is ok then it is probably a bad U7100 again.

 

[bjf]

R5187 measures fine. Replaced U7100 again. No change. After the first replacement I noticed that C7092 was shorted so I replaced C7092, C7091, C7090 and U7090. I have 0.8V on PPVIN_G3H_P3V42G3H. Not sure how that interacts with U7100 and ACOK, but I've been working under the assumption that I should be able to get ACOK with just a functional U7100 circuit.

 

[dukefawks]

Really, you did not check if there was 3V42 before asking about ACOK....?
Voltages on D7005? Resistance to GND on 3V42 bus?

 

[bjf]

Ha, I was wondering when you were going to chew me out for one of the various holes in my knowledge. Yeah, I was thinking I could get ACOK going and then work on 3V42. Apparently not. Replaced R7020 that was measuring correct resistance but not allowing voltage through. Done. Working. Thanks.