What should the output of the 555 IC on the HV PCB be?
SOLUTION: The output at pin 3 of the IC should be a 20-kHz square wave. This is adjusted with potentiometer R7. PROBLEM: There is no high voltage. The positive and negative 24 volts are present. SOLUTION: Check transistor Q3. The problem may be that the transistor tab (collector) may not be making good contact with the heat sink. PROBLEM: The schematics for the HV cutoff circuit do not match the board assembly. SOLUTION: There are three board revisions. You can tell which one you have from the table here. The schematics for all three boards are shown.
