[SOLVED]820-3437-B No backlight, no power from battery

[aurel476]

No backlight and no power from battery, history liquid damage (orange juice)

PP3V42_G3H 3.4v
PPBUS_G3H 8.3V (need 12v)

SMC_BC_ACOK 3.4V

PIN 17/18 OF U7100 5 OHMS
PIN 27/28 OF U7100 20 OHMS

 

[aurel476]

PPHV_S0SW_LCDBKLT 20V at startup and descrease

 

[dukefawks]

PPBUS is 8.4V on these. First lets get backlight back. Also expect a dead battery or SMC ahead. Corrosion around LP8550?

 

[aurel476]

Yes corrosion around LP8550

 

[dukefawks]

So what ya gonna do?

 

[aurel476]

i will replaced U7701,
Backlight is powered by PPBUS_G3H for this model ?
what is size of ball for this ship i have stencil Universal

 

[dukefawks]

Stencil? Why? New chip has balls. Read the sticky on backlight repair and check feed back trace to ball A5 when chip is removed.

 

[aurel476]

replaced U7701 same problem backlight 2 seconde at startup and stop,

 

[dukefawks]

SMC_LID high? Replace IO board and cable.

 

[aurel476]

SMC_LID 0,96V, 97 Kohms

 

[arghhh]

Replace IO board and cable.

 

[dukefawks]

1 goto 9

 

[aurel476]

i order io board and cable, what does it mean LID ?

 

[dukefawks]

LID as in lid, cover, etc. The LCD cover

 

[dukefawks]

Backlight should also come back if you power this on without the flat cable connected.

 

[aurel476]

yes backlight work without the flat cable, i replaced ioboard and flat cable all work solved thanks