Defective M92 Chips?

Nintendo Questions Nintendo Switch
1

I think I’ve been bamboozled.

I have just started getting into troubleshooting and repairing Nintendo Switch Consoles. One of the thing I knew I was going to need a lot of was M92 chips. So I ordered them in bulk on ebay to keep costs down.

Well, I had a V1 that kicked my rear end for a week straight. I couldn’t figure out what was going on with it.

It had a mangled USB port. I replaced it and verified continuity on pins with tester. I found a short on M92. Removed and short cleared. No short on BQ.

Installed new M92 and short was still gone. Plugged in official charger with tester and was reading 5V 0A with battery connected.

I was getting power from USB to M92. CC1 and CC2 checked good. Was missing the 10V on pin 21 for Mosfet gate.

I guess the good thing is it forced me to dive in a little deeper, but I’m short a few hairs now.

I noticed that 10 of the chips had the same lot number. I decided to pull a good M92 off another board. With the known good chip, I measured 10V on pin 21. Then I verified it would charge the battery…once. Not sure what happened after that. It went back to its original behavior. I shelved that one for now.

I tried one of these chips from this lot on a known good board. No voltage on pin 21. Put original chip in. Back to normal.

I told the seller that 4 or the 10 I received from that lot were defective and the other 6 are likely to have same problem. They asked me to test the other 6…

Anyways, today I’m working on a Switch Lite. Mangled port, short on M92 cap, removing chip removed short. I tried one of those chips. Yep, same thing. Then I tried one from different batch…same thing..then I tried a few more.

So at this point, I’m not sure how many M92s I’ve gone through. Think I need to take a break. Brains misfiring. Will probably try a known good M92 in that later.

So, I’m convinced that I got my hands on some bad M92s. But the fact that the first one went back to 5V 0A makes me not so sure. Maybe I did something wrong. Damaged something?

What exactly is everything that is needed to trigger the Mosfet gate? My understanding is just the CC lines and the power coming in. Is there anything else involved? Like the APU? I would like to rule out anything else.

2

I have an update this morning.

Good news…I guess…

I pulled a known good M92 off another board, popped it into this one, and PRESTO! The mosfets fired up. I noticed that with a 5V charger, pin 21 on M92 will read 10V, and it reads 20V with official charger. Interesting.

Connected battery and verified it is charging. Connected everything else and it is fully functional!

The bad news is that I most certainly received a large quantity of defective chips. Guess I get to attempt to get a refund on this. Definitely not testing every one. It wasnt just that one batch that was bad.

I wasn’t 100% sure at first because of my lack of experience working on these. And I remember now what happened to the V1. With the known good chip, it started charging again. Prior to putting the board back in console, I noticed the board was a bit warped (excessive heat and a lot of work). I only slightly bent the board with my hands and heard a slight cracking sound. So either a solder point broke or a trace is broken. Not sure how to pinpoint where that is. I assume the board is done for now.

My head was spinning a bit because I was working on like 20 of these ar same time. Wasnt taking notes so, yeah. Going to start getting a little more organized.

I guess the only question now is where I can get some good M92s. I know links aren’t allowed to be posted on here, but I think this is important information. I wasted a week troubleshooting because I wasn’t expecting these chips to be bad fresh out of pack.