820 3437, No image

[Noguinfor]

Working on 3437, with a bit humidity!!

This board initial it's working but without image. i hear the post sound and the keyboard had a backlight..

After inspect the board i noticed R5177 + R5178 bought are corroded! i clean the pads and replace the components! But the problem remained. after a better check on board i found R7611 with a bit off corrusion and i noticed the pin 1 off R7611 not making a contact with the pad because the corrosion! The problem start here!!

I clean the pads and replace R7611 but after that the machine when i plug the charger the fan only spin 1 time and stop!!! if i remove R7611 the fan always goes but don't work!!!

i double check R7611 and R7612 bought have a certain values!! No short's! I noticed too when i remove the R7611 i have a unstable voltage on pin1 (2.6 - 2.8V). With R7611 i have 1.8V while the fan works!

suggestions ? thank you

 

[2informaticos]

The divider R7611/12 sets the value of PP1V05_S0.
So check if get that voltage.

 

[Noguinfor]

Ok, already replace R7611/12 and u7600!! Fan start but stop and don't turn on! it's look's OK! so stupid, i only take the resistor and clean the pad and put it again...

 

[2informaticos]

So you get 1V05_S0?

 

[Noguinfor]

yes... when i put the charger on megasafe i have 1V05_S0 = 1.056V!

 

[2informaticos]

Board works now?
Check presence of other voltages.

 

[Noguinfor]

Now t's working! But only start to work after ultrasonic cleaner!!! After that the machines Start well and show image! so stupid!! but It's working!! thank you one more time