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820-3115 ppbus low, not turning on

B

BCN_Techs

Member
Hi guys,

Got another 820-3115 logic board with this measurements:


PPBUS_G3H - 1,4 V seems to be shorted to ground but cant find where.
PPBUS_S5_HS_COMPUTING_ISNS - 1,4V
PPBUS_S5_HS_OTHER_ISNS - 1.4V
PPDCIN_G3H - 17V
PP3V42_G3H -3.42V
PPVRTC_G3H- 3.45V
PP3V3_S5 - 3.3
PP3V3_S5 - 0 V ( not shorted to ground)

Is it possible that all that is shorted to ground through CPU?



CPU is getting warm, even hot.
 
B

BCN_Techs

Member
L7550/10/20 to ground is 1,8ohms. and 0.002 in diode mode.

Other big coils (diode mode):

L7100 - 0.004
L7630 -0.008
 
B

BCN_Techs

Member
Now i have another problem. No green light. Just put it in ultrasonic to clean all flux. Checked and R7085 is 33 ohms instead of 470Khoms. When remove Q7085 the value becames right. When put new Q7085 again 33ohms.
 
2informaticos

2informaticos

Administrator
Staff member
Is F6905 OK?
Do you have voltage on it?
DCIN voltage pin 2/U7000?
Did you properly solder Q7085?
Check the same voltages using fake charger, or bench power supply...
 
B

BCN_Techs

Member
2informaticos said:
Is F6905 OK?
Do you have voltage on it?
DCIN voltage pin 2/U7000?
Did you properly solder Q7085?
Check the same voltages using fake charger, or bench power supply...
Click to expand...

F6905 is ok. No voltage on it. DCIN pin 2 on U7000 0V. With fake magsafe ( i dont have so i injected by power supplu) injected voltage on pin 2 and F6905 let pass voltage through.


Q7085 is soldered good.

I am stucked at this point. Seems to be current protection but cant find what is wrong
 
2informaticos

2informaticos

Administrator
Staff member
Original charger detects leakage and stops to power the board.

Post some voltages around U7000 with bench power supply.
Check if R7010/11 both OK.
Also check for short to ground at U7000 pins.

Post exact value (ohm scale, measured onboard) for R7080/81 and R7085/86.

Please, do NOT quote an entire post visible few cm above; maintain the forum aesthetic...
 
Last edited:
B

BCN_Techs

Member
U7000:

Pins:

1/2 - 4.2V
3 - 1.06V
4- 3,4 V
5 - 0 V
6 - 3,4V
7/8 - 0V
9 - 0.5V
10/11/12/13 - 3.4V
14/15/16 - 0V
17/18 -1.4V
19/20 - 4.4V
21 - 0V
23/24 -1.4V
25 - 4.4V
26/27/28 2,4V


I'm injecting 16V. U7100 is getting very hot.


R7011 3 9Khoms R7010 30Khoms so they are ok.

R7081 -62K R7080 - 99,5K R7086 - 317K

And R7085 - 77Ohms Removed Q7085 And it's now 470 as must be. Changed Q7085 by new one. Now R7085 is ok. Guess it was broken while injecting.


P.S. COnected magsafe and R7085 again 77ohms so Q7085 must be fucked again.
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
"I'm injecting 16V. U7100 is getting very hot."
Change U7000 and Q7085 at same time.

Why did you inject 16V, and where???
 
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