Thanks, Peebee, that was what I was looking for.
I examined the second PS, and as you mentioned, one of the AC inputs is connected to the DC common.
What is strange is the installation sheet that came with this PS. It shows the connections between the transfo and the PS, and has the *fused*...
BTW, neither DC PS had a ground wire. So internally, how did the second PS have a reference to the AC input? They both had a 4-diode rectifier, and were set for half-wave via a jumper. Mmmm. Maybe I'm gonna have to break out the old breadboard and make up some PS circuits and try to...
An interesting problem came up at work the other day. We were installing a 3-wire pressure sensor (wires are COM, DC+ 24v, and SIGNAL (0-5vDC).
The transfo feeding the controller is 120v-24v AC, one side grounded on the secondary. The DC power supply for the sensor is fed from the same...
