------------Original Message: Date: Tue, 3 Mar 2009 08:13:37 -0800 From: dwight elvey <dkelvey at hotmail.com> Subject: RE: Recommendations for AIM-65 power supply? Hi Not sure who posted this part. I doubt they are using a single zener to regulate 2.5A. Maybe a zener resistor and transistor but it would be a large zener for that type of current. Dwight -------------Reply: Guilty as charged; I can't trace the circuit or read the diode number, but on closer perusal it is probably a reverse voltage protection diode across the output, and the 24V is completely unregulated. And that same closer perusal reveals a few more diodes, so it looks like a full-wave rectified supply after all. My point was that it's a really basic linear supply; transformer, 4 diodes and a 2200/35 cap (and that diode and a bleeder resistor). Incidentally, these printers were also used in a small National printing calculator, in case you run across one somewhere. mike