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A1278 820-3115-B no green light

H

hgoncalves

Active member
I have an A1278 820-3115-B that has no power.
I don't get green light or fan spin.

I have 3.4V on PP3V42_G3H
3.4V on SMC_BC_ACOK_VCC
3.3V on SMC_BC_ACOK
3.4V on R6929

U6900:
3.4 V Sys_onewire
18V Adapter sense
3.4V SMC_BC_ACOK_VCC

Already tried with new charging port.
Can you help?
 
Last edited:
H

hgoncalves

Active member
You're right.
The charging port was shorted (but strangely i've alreay tried before with other port with the same result), and after replacing it, now i get green light but no power or fan spin. Going to check major rails now.
 
H

hgoncalves

Active member
Hi,

I get this voltage measures:

PPBUS_S5_HS_COMPUTING_ISNS 12.5V
PPBUS_S5_HS_OTHER_ISNS 12.5
PPDCIN_G3H 19.9
PP3V42_G3H 3.4
PPVRTC_G3H oscilates between 3 ~ 4
PP5V_S5 oscilates between 3.6 ~ 5 on U7200. I think that the line is generated here, and this may be the problem. Am I correct?
 
2informaticos

2informaticos

Administrator
Staff member
Don't think you can get different readings in different test points of PPBUS_G3H.
Also, once you get correct PPBUS_G3H, no reason to check DCIN.
Avoid wasting time in the future.

Post SMC_PM_G2_EN level; does it oscillate?
Check for short and voltage pulse at all big coils.
Try to start in SMC bypass mode.
 
H

hgoncalves

Active member
Hi,
SMC_PM_G2_EN oscilates bettwen 0 and 3.4V

L7030 oscilates bettwen 12.5 and 13V
L7220 oscilates bettwen 0 and 3.4V
PP5V_S3 seams to be shorted. L7260 has 0.30 ohm and 0.0004V on diode mode.
 
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