I have been slowly working my way around possible issues on a water damaged switch. Having spent a long amount of time cleaning, I am now starting to work through the things that are clearly not right.
There are no shorts in the usual areas, and now that I have replaced the USB port, it slow charges both sides of the cable. When connected to a PC (with emmc disconnected), it is detected, but RCM locks up when trying to inject.
So, the only area that seems suspect is this part by the MAX77812, there is chip on the edge of the chip, and two of the capacitors have almost completely lost their metal on one side. The remaining caps do show a short, but with a bit of a delay, so that may be fine?
Does anyone know the values of these capacitors? I have another working board, but its a different type with a different chip / layout in this area.
From MAX77812 DATASHEET
if those cap one side connect to coil, they should be Vout cap. 22uF
IC has a chunk out of it…needs replaced
So I went through the data sheet and eventually found where it listed the recommended capacitors. And, given that the chip was damaged anyway, I removed it allowing me to see exactly where the traces are going.
This showed me that the output caps seem to be the ones marked green (so are presumably 22µf), and the sys cap I have marked blue (presumably 1µF if I am reading this right).
That left me with the red and yellow caps apparently all going between the same points.
At this point I removed the damaged caps, and luckily one of them had enough metal on the damaged side to get a reading! It turns out that these are 10µf caps.
That does leave the question as to what the smaller yellow ones are, as I can’t see them mentioned anywhere and the larger ones are the full 10µf, but never mind, mystery solved, and hopefully this will help anyone else searching for the info.
Did you measure the value off line or straight measure. In-line measure would have way off value most case
I measured it once it was off the board.
By any chance who can confirm the resistor in the red box is 10k or 100k?
I had a water damaged v2 board corroded on entire max77812 area
I will check to see if any of my current boards have it when I get a chance.
Sorry, all mine seem to be different revisions at the moment
From memory it’s a pullip to 1V8PDR
I received another water damaged MAX77812 SWITCH LITE BOARD.
Spent sometime on the caps measure. Here is the values for future reference if anyone find it helps