Lenny-
I wasn't able to respond to your October 17th posting until it had died of old age!
You had a question about the panel meter which doubles as a voltage and current indicator depending on the front panel push buttons. I remember a couple of replies that may have been helpful, but may have missed the mark regarding typical circuits used for such meters.
Take a look at the face of the meter movement. You will often find some small print near the bottom of the scale, that indicates the meter's basic sensitivity. For example, you might see "FS=50uA" or "FS=1mA". Such a marking would indicate the meter movement was a current-sensing meter with a full scale reading equal to the marked value.
When used to measure voltage, a meter movement usually has an external series resistor, chosen so the full scale current flows when a particular voltage is applied to the series combination. For example, take the case of a meter movement with "FS=1mA". Such a voltmeter is said to have a sensitivity of 1000 Ohms per volt. If the total series resistance is 1000 Ohms, full scale deflection will result from connecting a voltage of one volt. (A one milliampere DC meter movement may have an internal series resistance of around
50 Ohms.)There are two common ways to use such a meter movement to measure current. The simplest is to connect a "shunt" resistor in parallel with the movement. When the indicated current flows, the majority flows through the shunt, and only the basic amount flows through the meter movement.
Another method is to use the series resistor to make a basic one volt voltmeter, and measure the voltage across a larger value shunt resistor, so that full-scale current is equal to one volt divided by the resistor value, or resistance is equal to one volt divided by the full scale current. This approach might be used to measure a transistor's emitter current by reading voltage drop across its emitter resistor.
In either the voltage or the current case, switching the meter between circuits should have little effect on the circuits being measured unless meter resistances were low compared to the circuit resistances. With the above in mind, you should be able to figure out what is going on with your power supply's meter system. Your symptom of no meter reading might be simply a defective meter, but you should be able to check that. Just don't connect a voltage to it without a series resistor to limit the current to something less than its sensitivity! I'd suggest starting with at least 100,000 Ohms if you don't see a full scale value printed at the bottom of the meter face.
Fred