820-3476 green light but Dead

Chuck60

Member
PPBUS_3GH 12.6v , all PP3v42 3.42v, smc_pm_g2_en is 3.4 but no power up from power but or power on pads
 

2informaticos

Administrator
Staff member
Do you get 3V3_S5/SUS voltages?
Post PM_BATLOW_L and be sure to use original Magsafe 2 60/85W charger.
 

2informaticos

Administrator
Staff member
Now post PM_PWRBTN_L, PM_RSMRST_L and SMC_ONOFF_L.
Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L at same time.
If yes, check for pulse at PM_SLP_S4_L too.
 

Chuck60

Member
Pm_rsmrst_L = 3.3v
smc_onoff_L =2.0v

im gonna solder a wire to smc_onoff_L and see if I can simulate pwr button
 

2informaticos

Administrator
Staff member
Do you mean PM_SLP_S4_L is always high?
In such case, S3 voltages should be present too.
Post voltage at all big coils.
Also check ALL_SYS_PWRGD level.
 

Chuck60

Member
C1950 is water damaged and cap is gone. Hiow important is c1950 it?s not grounded just missing end cap. Shouldn?t it power up without it? U 1950 doesn?t look damaged I checked all the resistors around u1950 they?re values are good
 

2informaticos

Administrator
Staff member
C1950 corroded, usually damage trace to pin 8/U1950 too.
In such case, rebuild the trace,
Remove U1950 and inspect all pads (board and chip).

Do you get VCORE?
Post voltage for pins 7 & 3 of U1950.
 

Chuck60

Member
I have 3.42v on all areas that should have this voltage present. but not on c1950 or trace coming from board. even at the point where it emerges from the board just let of u1950 I will back track to see where the issue is and diode mode on track is OL. So I?m guessing something got knocked off or open trace.
 

Chuck60

Member
Ok I removed the u1950 and found the trade gone on pp3v42 on pin 8 I re did the trace and cleaned up the u1950 8 pin but I?m thinking this thing might be no good. I?m order a new one.
 

Chuck60

Member
Quick question when I connect the fan it brings g3h down. How often does a bad fan bring down a power rail ? Anyway I ordered a new fan
 

Chuck60

Member
Hi ok so I actually repaired the fan connector and fan
touched up the u1950 and it turns on and boots fine. I never installed c1950. It didn?t seem important. But I figured I?d ask you. How crucial is c1950? Thanks for your response.
 

Chuck60

Member
Oh and lastly I have a few isl repairs I?d like to get 10k resistor and other things that commonly go around them would you be able to tell me what are the most common so I can purchase them ahead of time?
 
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