820-3332-A water damage, works except sound and backlight keyboard

[kevinklinkmuller]

Hi there! I have an 820-3332-A which was dead because of water damage, I removed the visible corrosion with a toothbrush and alcohol (yes I know). It works perfectly except there's no sound and no backlight on the keyboard.
In system preferences under sound it shows no input or output devices. The ambient light sensor does work for the screen, and it shows that you can adjust brightness of the keyboard once the ambient light sensor is covered. but there's no light.
I have my board view and schematic ready. Although I have watched just about every one of Louis's videos, this is the first time I'm attempting to diagnose a board issue on a MacBook.
I would so very greatly appreciate any help I can get
thank you

 

[dukefawks]

First lets fix the sound. Check all supply voltages to U6201, 4.5V 1V5 and 5V all on the top of the chip on the diagram.

Is the backlight for the keyboard plugged in, very easy to get it under the board so you forget to connect it.

 

[kevinklinkmuller]

Sorry for the late response have been waiting for the doner board to arrive. The keyboard backlight is sorted, you were right, I'm a noob haha

So I checked pins 6, 24, 46 and 25, is that correct? All show up as 0v

 

[kevinklinkmuller]

Perhaps the chip itself is dead? Although it looks ok physically, the components around it look questionable

 

[kevinklinkmuller]

Wait, I have 5V on pin 46, PP5V audio HPAMP

 

[dukefawks]

Pin 9(1.5V), 24,25(4.5V) should have voltage. Check again, 4.5V comes from U6200.

 

[kevinklinkmuller]

Pin 9 1.5v
u6200 is not outputting voltage on pin 1 of u6200. I replaced a missing component (L6200)
I am getting 1.5V on u6200 as input on pin 6

 

[kevinklinkmuller]

Visually is looks like u6200 pin 1 isn't even there anymore. Perhaps burned away? Maybe replace u6200?

 

[kevinklinkmuller]

Ok so there was no continuity between C6201 and U6200 so I ran a wire, am now getting 5v on pin 6. Pin 1 now getting 0.5V

 

[kevinklinkmuller]

Duke, together we're going to make this board great again. I know it

 

[kevinklinkmuller]

Ok so I replaced C6203 because it was shorting PP4v5 to ground. WORKS! But after about a minute or so the internal speakers don't work and don't show up as an option in system preferences. I only have "digital out" as an option. Microphone WORKS though

 

[dukefawks]

Could be headphone jack, plug in headphone and see if that still works.

 

[kevinklinkmuller]

I think you're right, I disconnected the headphone port and speakers work fine now. I've reconnected it but now there's speakers but no headphone out. and the connector on the headphone socket does look a little burned so I'll replace that and see what happens. Thank you good sir Duke!

I have a different issue I just discovered with this machine, I'll put together a new post as per the forum rules