Voltage Issues =[

So I’m stuck at the testing stage right before plugging in all the IC’s. The voltage between all the green and purple contacts cycles between 3.6V and 5.0V, which is weird as in itself, however there doesn’t seem to be ANY voltage drop between the green and the blue contacts. Also, the voltage between the purple and blue points is identical to the voltage between the purple and green ones, so I thought there might a short but I checked for continuity with a multimeter and they don’t appear to be shorted. I checked the power supply and it’s giving a constant 9.5V supply. Does anyone know what else to check for? I’m at a total loss.

Perhaps to begin check voltage of 7805 and 7905

So I noticed someone else was having a similar issue as me, and replacing the TC1044 seemed to sort them out. I just received two TC1044’s and replacements for both of the voltage regulators.

I did some preliminary testing before replacing any parts, and the voltage drop between the purple and green points were cycling between .50V and.70V Really strange… There was still no voltage drop between the blue and green points though they were not continuous. Pin 1, going from left to right, of 7805 cycled between .18V and.53V, pin 2 appears to be GND, pin 3 cycled between .50V and.70V, which is weird because 7805 is supposed provide the positive rail, right?

For the 7905, pin 1 seems to be GND, pin 2 cycled between .54V and.67V, pin 3 has no voltage though it’s not continuous with GND.

First, I replaced 7805, for a brief moment, the voltage between the blue point and green points look good though the points between the purple and green points remained off. But I revisited the board 10 minutes later, and the drop between the blue and green points went back to zero. T__T

I took out the TC1044 and replaced it with a socket, I plugged in a new TC1044, and nothing changed. I then replaced the 7905, and still nothing changed.

I still don’t really have a clue what’s going on. Any help or suggestions would be greatly appreciated.


I haven’t soldered in either the audio or MIDI jacks because I want to fit them into an enclosure first. They’re all plugged in and making contact with the pads while I’m testing, but could that have anything to do with it?

The results of the voltage testing procedure should be the same no matter how far you went into the assembly (so it’s not a problem that you have some extra parts soldered).

There seems to be a problem very early in the circuit since you are not getting your supply voltage on the input pin of the 7805. Have you checked for a short between GND and +5V? Have you soldered a switch or just shorted SW0? If so, have you checked for continuity between both “sides” of the switch?