Thanks so much for the photos. That’s very helpful.
I notice that you do have a lot of rough looking solder joints. Most likely, the messiness of your board is causing these problems you are experiencing. You might want to try to clean up the joints with lots of solder on them…they will have a tendency to become oxidized and crack. There also seem to be a lot of tiny pieces of solder sticking out from many of the pads…these can short to the ground plane or other pads very easily…please clean those up by removing much of the extra solder on most of the pads. The microcontroller has a lot of burnt flux around many of the pins that you have been soldering to a lot (especially around pin 6)…try to remove this with some high percentage rubbing alcohol or acetone on a q-tip. It actually can become somewhat conductive. In general, try to use less solder on each joint…it’s much easier to control if you use solder that is very thin in diameter (I use .8mm wide solder). Also, it’s usually much better to use much thinner wire to run jumpers so it’s easier to control and you don’t accidentally short pins together with the thicker wire.
There is a large blob of solder on one of the pins of R11 that I am concerned may be shorting to ground…try to fix that.
There is a via right below the “R” of the word “RED” next to the bypass led. Make sure that nothing is shorted to that via from the midi in header.
For questions 2, I was asking about what is happening on pin 6 of the microcontroller when you press the bypass switch (not the LED). Make sure the bypass LED pins aren’t shorted before you check this (just in case they are connected).
The goal is to get the microcontroller cleaned up enough so that we get 5v on pin 6. If you are confident in your jumper running ability, it may help to cut the trace coming from pin 6 to ensure that nothing around the LED is causing this 4V issue.
-Brach