I see references to measuring "quiescent" or "idling" voltages in a circuit. Obviously a jack must be inserted in the box to turn the circuit on, but does quiescent measurement require the footswitch to be on or off to feed input into it? Also, does the cord plugged into the jack need to be plugged into a source (guitar) and does it matter if the guitar volume is rolled off or not, if no string is being plucked? Thanks, hope this question isn't as dumb as I think it might be!
It means "power is on, no signal into the input".
The footswitch position doesn't make a difference as long as the effect is not one of those that oscillate when the footswitch is in the off position.The cord plugged into the input jack doesn't need to be plugged into a guitar, but if it's picking up a lot of hum, that's a signal, too. I stick a phillips screwdriver of an appropriate size into the input jack to turn on power. This also shorts the input jack, so the input is guaranteed to be 0V, just what you want for testing idling voltages.
You could also insert a dummy 1/4 " plug (cut from an old guitar cable) with the tip jumpered to the ground so your input reference is at ground as RG suggests. this will also turn on your battery power- 2 birds with 1 stone. I keep one handy on my bench for this purpose.
great info, as always. I have learned so much from this forum, you folks should give degrees!