I’m having problems with a 4pm build. To cut a long story short, I blew the ic2 chip because I did something dumb. I replaced it but now switches S3 and S4 don’t do anything. Switch s2, strangely, seems to cycle LEDs 4+5. I can access nearly all the menu options with the encoder, except the system + midi options (when scrolling on, it jumps back to the first menu option). I’ve checked all the joints + orientation on the 595, 165 + the resistor network, but here’s the strange thing. If I touch or apply pressure to 165 when it’s powered up, the menu flickers, and sometimes the system menu becomes available. This seems to indicate a short or issue with the 165…
Before I have to desolder another 165, how can I test whether its working properly? I checked another thread on here, but the link for the testing procedure had been removed…
Show us some pictures of the soldering. It does sound like a soldering issue to me. Did you use sockets? Then maybe the IC doesn’t properly sit in its socket.
Thanks for replying
Posted some images - it looks like I’ve exposed the 2nd layer of the PCB when I removed the old chip. Could this short the chip out? If so is there anything I can do?
Is there some way to find out which pins do what so I can test them…?
Please redo the solder joints. There are good YouTube videos on how to solder. Most of your joints have too little solder on them and look quite dry. Chances are high that something else stops working eventually.
I would suggest you retouch all joints again. Heat both the pad and the pin at the same time with the iron, then feed some fresh solder. If pin and pad are both hot enough, the solder will immediately connect both nicely (watch some YouTube videos if you’re unsure). After you redid all the joints, it should be working again.
Thanks for the advice I’ll do that. I’ve ordered a solder sucker + a low profile socket. I’m also going over both boards again to touch up any other bad joins…
Don’t take the chip out just to add the socket. You can always do that later if you find the chip is dead. Chances are, you’ll rip off pads while desoldering and then you create yourself more problems.
Many of your solder joints need to be redone - but that’s okay. Chances are very high that it will solve your issues.
So finally had time to get on with this project. Unfortunately I think I may have pulled out a solder pad when I removed the old chip
When I solder this pin, the solder just clumps round the pin + doesn’t run into the board, and despite the soldering the joints 3-4 times the issues are still the same, buttons 3 + 4 still don’t respond at all. I’ve enclosed a piccie, although it’s not that clear (done on my phone)! Pin is second from right on top row
Sorry, but I can’t see that image. The text is blue and the mouse turns into a hand symbol, but it doesnt appear to be a link or embedded picture.
Ok I’ll try + reload it. Thanks for responding
It looks to me as if your solder doesn’t have a flux core. Without flux, this is pretty much impossible to do. I suggest you get some flux (e.g. flux pen) and redo all your dry solder joints, as the ones on your second image don’t look much better than the ones on the first image.
And please, read up on how to solder. Here’s a good link with a video:
I shall do as you say. Thanks for your patience. I must admit, I’m definitely more musician than solderer
That’s okay, we all started one day It simply doesn’t make sense to fix one symptom (button not working) when the the underlying issue will eventually create more problems down the road.