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A. No Display Condition...
1. Check main fuses or circuit breaker.
2. Check blower motor overload...If tripped, reset.
3. Check fuse 1 or fuse 2 and if either are blown, replace.
4. Check to make sure the EMERGENCY STOP (E-Stop) button is not depressed.
5. Between pin 1 and ground of the 15 pin connector you should be getting 24 V.
6. If no voltage is present at pin 1 and ground, double check Step #1 through Step #4.
7. Take voltage reading across the microprocessor 9 pin connector nos. 1 and 2.
If there is voltage, replace the computer.
If there is no voltage, there is a faulty wire(s) or termination(s) between the 15 pin connector and the
microprocessor.
NOTE: In this next section ALL voltage checks must be done in the operating mode with the
appropriate microprocessor dot on!! Also appropriate LED (light emitting diode) output light
on!!
NOTE: In this next section when checking for voltage you are looking for 24 AC volts unless otherwise
specified.
B. Drive motor reverses but does not go forward, blower motor runs...
1. If computer dot (first dot on the left) does not come on, replace the computer.
2. Check for voltage across the coil of the forward contactor located in the rear panel box. The contactor
according to your diagram is marked CR2. The coil markings A1 and A2.
If voltage is present, there is a faulty wire(s) or termination(s) between BS2 and contactor coil (CR2).
If there is voltage across the two (2) BS2 terminals and no voltage across the two (2) BS2 terminals,
replace the arc suppressor (A.S.) board.
If there is voltage across the two (2) AS2 terminals on the arc suppressor (A.S.) board, the problem is a
faulty wire(s) or termination(s) between the AS2 board and the 9 pin computer connector no. 8, or faulty
computer.
C. Drive motor works in forward mode but does not reverse, blower motor runs...
1. If computer dot (second one from left) does not come on, check program to see if set for reverse.
2. If set for reverse, replace computer.
3. Check for voltage across the coil of the reversing contactor located in the rear panel box. The contactor
according to your diagram is CR3, also the markings on the coil are A1 and A2.