I've just finished building 2 LCBPS power supplies. When I apply power one of them works fine, it's easy to adjust the voltage to be exactly +15 and -15 relative to ground. On the other on it is possible to adjust the voltages, but it requires a lot more turns on the pot. And I am not able to get the voltage down to 15 on either side before I run out of turns (now 16.5 and 17.2, more or less). The board looks fine, the soldering does not deserve any beauty prizes but it should work. The only difference I can see between the two supplies are the trimming pots. They all seem to be 5K, but on the faulty supply there is a number 0807 (which is also the number of these parts on the LCDPS I have), and on the working supply 0726 (for one of the pots anyway, I can't read the lettering on the other trim pot without removing it). Could this be the problem, or is that just a production run number?
Can you suggest where else to start looking?

EDIT: Argh! Never mind, me stoopid. Just read http://www.twistedpearau...t.aspx?g=posts&t=586 and that's exactly what I did, swapped the two ICs. That's what you get for not reading labels closely...

Edited by user Wednesday, July 1, 2009 11:32:21 AM(UTC)  | Reason: Not specified