Well...That was fun!
I went out into the garage to cast some bullets. Hooked up my LEE 20 pot to the PID and when I went to move the probe, the sheath on the probe wire touched the hot lead on the relay on the back of the PID and sparked. The leads on the back of the homebuilt PID are simply covered with a plastic cover. There was just enough room on the side for the probe wire to barely touch the hot lead.....Damn!
The PID still turns on and it is reading temperature, but it wont shut off the AC power going to the furnace. I thought maybe the relay was stuck.
But I checked to see if there was 32V DC going to the control side of the relay.......nothing. So I just ordered up a new PID controller and relay from Auber.
BTW, interesting to note. The Lee Precision Pro4-20 pot really maintained temperature. Once I set the rheostat to 680 degrees, it held within 10 degrees for an entire pot of lead. I thought the knob on the back was simply a rheostat but I could hear the pot cycling on and off...........??????