I figured as much. And, with a 10K ohm bleeder resistor that I added on the output (another added safety feature), the voltage dropped down to 5.2 and change - within spec.
JRJ On 8/22/2015 6:19 PM, Dave G4UGM wrote: >> >> Also, I now know why the +5 V is high. It has a UA 7805 3 terminal > regulator >> serving as a voltage reference for a TIP-3055 so the supply can provide > more >> current. That 7805 has a forward biased diode between the center terminal >> and ground, thus raising the output voltage by right around 0.5v. I > expect I >> will leave it alone. > > > When used as series pass transistor the TIP-3055 will usually drop 0.6v > across the emitter under any significant load. Adding a silicon diode in the > 7805 base is the normal fix... > > http://www.bristolwatch.com/ele/basic_power_supplies.htm > >> >> The same design is used for the +24V, which comes out at 24.2V. >> >> So, odds are that this supply could drive two floppy drives. >> >> JRJ >> >> >> JRJ > >