1708 controller rapidly triggering most buttons

[Arakon]

Hi.
I have a 1708 controller here that is going nuts by itself. Basically, all buttons except for the sticks (directions and L3/R3), LT and RT, and the B button are constantly triggering at extremely high speeds. I tracked the issue down to the board with the USB port, the wider board itself is fine. No visibly burned parts. Anyone ever seen this before? The controller appears to have been untouched, no traces of being opened.
This happens on the console, on a PC, via BT and via USB.

[RDC]

I haven't seen that exact issue, but this is the second 1708 in the last week or so that I've heard of where those top board buttons aren't acting right.

It would have to be either an issue with U4 on the top board there, it's an IO Expander (PCAL6416A) and deals with all of the buttons on that board, or it could still be an issue with the bottom MCU board as that is the one that 'talks' to the IO Expander chip. Then any traces, Vias and such between the two.

You'd need to connect a Logic Analyzer up to it to see what is going on there, as a DMM or straight O-scope will be of no real troubleshooting use aside from seeing if U4 is getting power, and even then if it's dropping out really fast causing the issue a LA is still the better tool to 'see' that problem.

https://www.acidmods.com/forum/index.php/topic,43981.0.html

[Arakon]

The bottom board is fine, it's working flawlessly in combination with a different top board.
Unfortunately, I have no logic analyzer. I did notice that Q10 has slightly dull edges compared to other mosfets on the board, but I doubt that's related to this.

[RDC]

Then does that problem go with that board when tried with another MCU board?

If so, then I'd still suspect U4 more than anything else. Since the rest of the buttons and controller worked fine, the power rails should all be working correctly, though there could still be a slim chance of an issue with a power Via/trace going to U4.

It's a PCAL6416HF, 4x4mm QFN, that can be found at DigiKey and like parts stores online.

[Arakon]

You were right, it was that chip. I replaced it from another controller and at first, had the exact same symptoms, until I reflowed the chip again.. now that part works.
Only other issue now is that BT stopped working on that back board. The other back board I have works for BT, but has physically destroyed sections that prevent the entire left side rumble stuff from working.
Any known "easy" fix for the BT module not working? fuses/diodes that could be damaged?

[Arakon]

O-kay.. apparently it just wanted to sleep over it for a night, because today BT is suddenly working again. So now I got 2 working controllers out of 3 defective ones. Thanks again.

[MattP79]

Hi.
I have a 1708 controller here that is going nuts by itself. Basically, all buttons except for the sticks (directions and L3/R3), LT and RT, and the B button are constantly triggering at extremely high speeds. I tracked the issue down to the board with the USB port, the wider board itself is fine. No visibly burned parts. Anyone ever seen this before? The controller appears to have been untouched, no traces of being opened.
This happens on the console, on a PC, via BT and via USB.

Yes! I have one which I bought with a dodgy down D-Pad button (domed metal pad has collapsed) and after replacing the D-Pad sticker I find xintermittently the RT / RB cycle 0% to 100% and various other buttons trigger until a joystick is touched and then it works normally for a while.  Considering how you resolved your controller I'll also be looking at U4 and giving it a blast with a heat station.

Thanks to RDC and yourself for this helpful thread!