A1466 820-3437-B no power

[hgoncalves]

Hi,

I have an A1466 820-3437-B, that has fan spin, green light, but no power on. It gets to 250mA.

PPBUS_S5_HS_COMPUTING_ISNS has 0.135 on diode reading, witch seams to be very low (compared with other board, but not sure if ok), and 8.59V.

Can you help?

 

[2informaticos]

"PPBUS_S5_HS_COMPUTING_ISNS has 0.135 on diode reading, witch seams to be very low"
Not true!
Keep in mind, Q7130 has a internal Schottky dioded added on the low-side; consult the schematic.

Which big coils get voltage?
Also check ALL_SYS_PWRGD level.
Inspect U1950 for corrosion.

 

[hgoncalves]

Hi,
TKS.

ALL_SYS_PWRGD = 3.3V

U1950 had a bit of corrosion and so I've replaced it (but with same result).

L7310 = 1.7V
L7320 = 1.7V
L7630 = 1.0V
L7430 = 1.2V
L7560 = 3.3V
L7520 = 5.1V
L7130 = 8.59V

L7701 = 0V
L3095 = 0V

 

[2informaticos]

U1950 has 3V at pin 3?
PLT_RESET_L comes high?

 

[hgoncalves]

U1950 pin3 = 3.4V
PLT_RESET_L has 3.3V

 

[2informaticos]

Check all resistors and coils from page 11.
Also check all SPI Bus Termination resistors and their traces.
Clean J6100, if looks dirty/corroded.

Try known good BIOS.

 

[hgoncalves]

The culprit was R1280.

TKS!