DigitalZombie
Member
Finally got around to this one after having the PCB since last July. I try to breadboard everything first to see if there's any mods I'd like to do before involving any solder. I couldn't get it to work properly, dealing with terrible misbiasing issues. Right away I could see where I was supposed to be getting 9v I was getting closer to 8.5v. Still workable, but -9v was closer to -7.5v, and 18v wasn't even breaking 15v. I assumed it was something on my breadboard layout and trusted the board was correct. I finished soldering and was about to box it up today when I figured I'd just do a quick search and see if the schematic was available anywhere else to compare. Well, I found another forum that referenced this schematic and they pointed out how two of the polarized caps in the voltage regulator section are backwards - namely C102 that connects pins 2 & 4 of the TC1044, and C103 that's on the -9v rail pin 5 to ground. I put that together on my breadboard just now and viola, all voltages are actually correct.
The PCB needs to be updated, or at least a note in the build docs to flip these two caps around. Going to box it up today after I make these corrections and give it a spin.
The PCB needs to be updated, or at least a note in the build docs to flip these two caps around. Going to box it up today after I make these corrections and give it a spin.