820-2915 chime no bklt but 10v at f9700

[Chuck60]

Hi I have a issue with this board I have checked g3h in a few different area it 11.5v I have a green light on charger and it chimes. But no backlight

 

[Chuck60]

I?ve tested with a known good screen and I have backlight on keyboard but not screen :/ checked feedback. area no liquid damage anywhere

 

[2informaticos]

"I have checked g3h in a few different area it 11.5v"
Please post what exactly measure on a board.
You are the first interested to post clear information!

I hope it is not 3V42_G3H.
And if is PPBUS_G3H is also bad value; if battery is not connected.
F9700 also means PPBUS_G3H, so I don't understand how can you get 11.5V and 10V at same line...

I hope you already confirmed image on internal LCD.
Why would search for backlight, if not?

 

[Chuck60]

Ok it?s up and running thanks 2informaticos

 

[Chuck60]

One question I clean my boards with just alcohol bath. Since I don?t do this repair for a living Buying a crest ultrasonic seems out of my reach. What is the best method besides ultrasonic to clean them?

 

[2informaticos]

To clean small areas, after changing pieces, use tootbrush and IPA.
Ultrasonic bath is only needed when you have large areas corroded, or accumulated crap under BGA chips.

BTW, which was your solution in this case.
It could help someone else in the future...

 

[Chuck60]

I?m sorry. it was weird im not sure I?m explaining it right a capacitor c9435 although it wasn?t a complete short it was bringing down ppbuss_g3h And resistor r4650 for mux after that all the voltages where normalized. Everything just worked