Macbook Pro 2012 820-3115 no orange light

[arnonabuurs]

Hi, I have a 3115 that doesnt get an orange light. Green light is present but seems to blink a little. No liquid damage after checking with Microscope.

Voltages measure as follows:
PPDCIN_G3H: Moving between 16.2 and 16.8v
PPBUS_G3H: 12.54 - 12.57
PP3V42_G3H: On U6901 Swinging from 3 - 3.42v on pin 4 stable on pin 5
PP5V_S5: 4.97
PP3V3_S5: 3.29
PP3V3_S4: 0v
PP5V_S0: 0v
SMC_Reset_L: 3.45v
U7000: pin 17/18 and pin 27/28 , 3.5ohm and 20 ohm,

Resistors R7005/7011/7010/7051/7052/7021/7022 all OK (accept R7010 measures 0 but also on a working board i guess its an error in the schematics which mentions 30.1k).

Suggestions?

 

[dukefawks]

Without a recognized battery the light will not turn orange on these.

Was this a liquid spill?

 

[arnonabuurs]

Hi Duke, no no obvious liquid spill checked it with microscope, SMC area clean too. With battery connected it also stays green with a little blink

 

[larossmann]

Since you say PP5V_S0: 0v I am guessing this is dead. Since you mention PPBUS_G3H and PPDCIN_G3H jumping back and forth I imagine the charger is being shut off due to a short circuit up ahead. What is the resistance to ground on PP3V3_S0/PP5V_S3/the rest? My guess is short circuit to ground on PP5V_S3.

 

[arnonabuurs]

I checked following lines and didnt find short to ground yet:

PPDCIN_G3H: 0.629
PPBUS_G3H: 0.450
PP3V42_G3H: 0.363
PP5V_S5: 0.523
PP3V3_S5: 0.157
PP3V3_S4: 0.411
PP5V_S3: 0.145
PP5V_S0: 0.423

On a working board I get

PPDCIN_G3H: 0.633
PPBUS_G3H: 0.446
PP3V42_G3H: 0.353
PP5V_S5: 0.514
PP3V3_S5: 0.132
PP3V3_S4: 0.376
PP5V_S3: 0.142
PP5V_S0: 0.489

 

[dukefawks]

Is PP5V_S0 pulsing. Check carefully, hard to catch the short pulses on multimeter, best to use a scope with "one time trigger" activated.