One More Try for Negative Channel...

A project log for Bench Power Supply

Designing an open source, modular bench power supply to rule them all.

The Big OneThe Big One 06/04/2015 at 15:380 Comments

The original negative channel didn't end up working properly after all... I must have had some bare wires somewhere that weren't quite touching, because as I was probing it with my multimeter while trying to get the overcurrent light working properly, something sparked and blew a trace (it was pretty cool actually, I had never personally seen a trace blow before! ;-)). Yesterday evening I soldered up another one (I have it down to about 45 minutes now!), but there was a short between VB and GND that I couldn't find, which took me another 2 - 3 hours to track down. (End result: I had put the solder paste on one of the op amps a bit too close to the chip, and there was a bridge between two pins that I couldn't see without taking the chip off the board.)

Anyway, after a long and frustrating time to troubleshoot, I got it working in the end (95% sure this time). The voltage light works, the overcurrent light works, voltage + current limits can be set via the GUI (I had fixed that particular software bug a day or two ago, I don't think I remembered to post about it). More testing is definitely needed, but I think that things are looking good!

Outstanding issues: