Hi, so I have a Switch HAD-CPU-01 board that does not charge. Originally it did not power on, which I fixed by replacing M92 and some shorted caps around it. Just for the sake of it I’ve tried replacing P13 and I’ve measured all around the board looking for shorts, and I can’t seem to find my issue. What I have found is that I get partial voltage readings when I plug the board in and leave the battery unplugged. There is no voltage making it’s way to the BQ chip (which I replaced also). On the backside of the board, I also do not measure any voltage around what I believe is the fuel gauge. I have found 2 what appear to be shorted caps circled in the image, that when measuring 2 other boards (of different revisions, which may mean something) those same caps do not appear shorted. I’m still learning how to use a multimeter (more specifically, what modes I should be using to test specific parts of the board) and I am pretty stuck on where to go from here. I’ve replaced the charge port twice to ensure that wasn’t my issue. I’m just looking for some advice on how to proceed, and where I need to look to figure out why BQ is not receiving any power. Thank you in advance. Image: ttps://drive.google.com/file/d/1sENMc2YDvMB0XBEeEXvRJBuot-zhMpac/view?usp=drivesdk (add h to front)
The drive is not accessable.
Sorry, try this link: (h in front of course) ttps://photos.app.goo.gl/19Zp75oFkJgu67pN8
I wonder how that could be? Wouldn’t I be experiencing memory/boot issues? I was able to download one of my purchases games without issue, and the system boots up without fail each time. Would this cause BQ to receive 0 power whatsoever?
I should have read everything in detail. 
So your Switch is turning on. And you can download and play without any issues beside the not charging of the battery?
You changed the bq and you checked the voltages around the bq?
VBus is that what your usb c charger is delivering.
I’d recheck M92. Measure the voltage on the two mosfets on top of the fuse; those mosfets are controlled by the M92 and both need to be powerer on to allow current to reach BQ. If M92 is not turning on this Mosfets your BQ won´t get power over the USB.
iirc a healty Switch should have 10V on the gates and 5V on the outputs. If something is off it may be a bad M92 or something wrong with the USB detection circuit as M92 wont turn this mosfets on until it detects a USB plugged in.
Correct.
There is 0 voltage from any of the VBus marked areas. On 495 I get 0.03V, 0 everywhere else.
Mosfets are the larger 6 prong chips, correct? Should I be measuring these with the battery plugged in? I’ve been taking my measurements with only the charger plugged in. The one to the right, closest to the charge port gives me 0.03 V, and the one right above it gives me the same. I pull 0 from the others.
Those two are. If your board is a V2 they’ll be arranged slightly different way but yes, if the M92 is turning these two on, you should be measuring 5V on both Source/Drain and 10V on the gates.
M92 should turn them on even with no battery connected.
So is this most definitely M92 related or charging circuit? If the replacement M92 was bad, wouldn’t the Switch still struggle to power on? Since replacing it solved the no power issue. I’m at my wits end here, lol. My problem is I don’t know what the charging circuit consists of in its entirety, I know M92 and BQ are the big ones alongside P13 for HDMI signal, which I don’t really get voltage readings on either. Then there’s the fuel gauge on the other side of the battery, which also isn’t receiving voltage. Anything I’m missing?
P13 should be getting power once the 3.3V regulator is turned on after powering on the console.If the console is booting this should be fine as this 3.3V rail is mandatory for booting. BQ must be ok as it creates the main Vsys rail for the console to boot.
Now, regarding the issue; I’ll be honest with you, I have no idea what’s causing this. I’ve recently received a console with this same exact behaviour and even after replacing BQ,M92,mosfets and all I could think off, I couldn´t manage to make it work.
Things you can try:
- Check the gates voltage on the M92 (not the pad under). If there is 10V there but they are not reaching the mosfets you have a bad soldered M92.
- Connect a USB cable (Just the cable, no power) and measure resistance between CC1 and CC2 on M92. Iirc should measure 10k. If you measure open or short you have a problem with your USB reaching M92. Might be the filter near the fuse or bad USB port.
This is just pure theorization but on my case this was caused by a third party charger that I think somehow broke some traces somewhere that only made contact when the board was extremely hot and traces expanded, so the console was charging after changing the mosfets but 5 minutes after it just stopped.
I will try this, thank you. For clarification, because I am still learning terms, when you say check the gates, where exactly am I probing?
