Interface connector pinout between the PFC-20 power stage and charge control board.
Joe Smalley 
4/29/2002

1= +15 SUPPLY FROM POWER STAGE 
2= -15 SUPPLY FROM POWER STAGE 
3=CONTROL VOLTAGE TO POWER STAGE (<0.5 = 0%, >5.5 =100%) 
4=GROUND 
5=OUTPUT/100 (5VOLTS = 500 VOLTS) FROM POWER STAGE 
6=REF 7.5 FROM POWER STAGE 
7=BUFFERED LEM OUT (5 VOLTS =42 AMPS) FROM POWER STAGE 
8=BUFFERED THERMAL BUS (1V=78F,4.5 V=180F) FROM POWER STAGE 
9=N/C 
10=N/C 
11=N/C 
12=VOLTAGE LIMIT LED FROM POWER STAGE 
13=OVERVOLTAGE SHUTDOWN LED FROM POWER STAGE 
14=CHARGE CONTROLLER IN CONTROL FROM POWER STAGE 
15=BOOST MODE (INPUT CURRENT IN CONTROL) FROM POWER STAGE 
16=FANS ON FROM POWER STAGE 
17=ENABLE TO POWER STAGE 
18=INPUT/100 (5VOLTS = 500 VOLTS) FROM POWER STAGE 
19=THERMAL CUTBACK FROM POWER STAGE 
20=THERMAL SHUTDOWN FROM POWER STAGE 

Shorting pin 17 to ground will prevent the charger from putting out power. This is the normal way to put the charger to sleep. The fans will run and the lights will stay on but no power will flow.

Pins 1 and 2 supply power to the charger logic. Loading these pins and altering the voltage by more than a volt will cause erratic or permanent damage to the charger. There are various power supplies installed in the different production runs so the available power cannot be generalized. Beware that the charger fans are normally on low speed and will demand significantly more power from the +15 line when the charger is hot. If you load these pins with a lot of load, you may find that the logic power supply will collapse when the fans try to come on high. The -15 line has only about 150 milliamps available.

Shorting pin 6 to ground will blow up the power stage. Don't do it. It is not covered by warrantee.
Shorting pin 18 to ground will prevent the charger from putting out power. Releasing it will cause a large transient. Don't do it.

Pins 12, 13, 14, 15, 19 and 20 are 5 volt logic signals in parallel with the board LEDs. Over driving them will burn out the LEDs on the power board. Shorting them to ground will prevent the LEDs from coming on for the duration of the short although they will work when the short is released.