Another 820-2879 No green No orange Wont turn on

[Mac-N-Sauce]

Has substancial liquid damage. Have PP3V42_G3H, PPBUS_G3H,SMC_BC_ACOK(3.23v)
When I check the power on pads i get 2.4v for SMC_ONOFF_L.
Not sure what is pulling that low. I do not have an ultrasonic to clean the board.
Any thoughts? I have checked the ISL6259 and have 4v on ac in, I have pin 14 CHGR_ACOK, I have 3.4v on SMC_RESET_L

 

[dukefawks]

That 2.4V is causing the SMC to be in bypass mode so no green light. Check what is pulling that down, probably corrosion in KBD connector.
Also measure resistance to GND on 3V42 bus and on the RTC Xtal, many times the MCP will be dead too.

 

[Mac-N-Sauce]

Ok, I cleaned some minor corrosion on the KBD connector and I know have 3.4v on power pads, but still can not get green or orange light(brilliant by the way Duke)

So, now how would I proceed? It was just a small amount of corrosion by the way.

 

[Mac-N-Sauce]

I do not have MCP_PS_PWRGD

 

[dukefawks]

I asked more things! Also check if what the voltage is on ADAPTER_SENSE and F7040.

 

[Mac-N-Sauce]

ADAPTER_SENSE 16.5v
F7040 12.57v but it appears to get voltage then drop, then get it again
i check diode measurement for RTC_CLK32K_XTALIN it is .810, not sure if that is correct. I am not sure what point exactly was the "RTC Xtal" also not sure what point you mean by " 3V42 bus"

 

[dukefawks]

You have main voltage on the SENSE line that is why there is no green light. Bad magsafe board or corrosion under connector.
3V42 bus is PP3V42_G3H, measure resistance to GND plz.

 

[Mac-N-Sauce]

PP3V42_G3H in diode mode with no adapter plugged in is .28v, new magsafe board and have green light. Checked a 2012 13" model 820-2936 it had .32v on PP3V42_G3H
Not sure how close they have to be

 

[larossmann]

he said resistance, not diode mode

 

[Mac-N-Sauce]

If i am understanding correctly(no guarantees) I measure PP3V42_G3H at 3.2k ohms on pin 5 of U6901

 

[dukefawks]

3K tells me the MCP is most likely dead, it should be over 25K in a good board. Do you really want to continue this board into the hell hole?

 

[Mac-N-Sauce]

Sounds like a parts board to me. Just curious, would that be a similar repair to the smc?
Can not seem to get a win on these.

 

[dukefawks]

It the same as any BGA repair. Getting a good MCP89MZ is even more of a gamble than finding good SMC chips.

 

[Mac-N-Sauce]

Ok, thanks again for your patience with us.