Have a payne high eff furnace with a/c and a skuttle model 2001 humidifier.
The problem is the humidifier is not kicking on.. I have continuity across the humistat when on but I have no power at the switch. I went back to the control board on the HUM terminal and have no power there to ground. Furnace is working OK accept the humidifier.
Questions:
What voltage should be at the terminal ?
Is there a fuse linked to the hum terminal?
Any help is appreciated.

Usually the HUM terminal is 24 volts. Another 24 volt transformer will work just isloate the new transformer from the circuit board.

Hvac
Does the hum terminal on the board only give power to the humidifier?
If so It is all right to add another 120 to 24v trans on the furance isolated from the furance board and connect directly to the humidifier control switch?

Thanks for your quick response..

If so It is all right to add another 120 to 24v trans on the furnace isolated from the furnace board and connect directly to the humidifier control switch?

Yes as long as the control switch is isolated from and other source of power.