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 “EMERGENCY STOP”
5.Across nos. 6 and 8 you should be getting your 208 V or 240 V. The J12 connector pin 1 and 3 you should be getting 24 V.
If no voltage is present double check Step #1 through Step #4 and also check wires and terminations at these points.
6.Take voltage reading across the microprocessor 9 pin connector nos. 1 and 2.
If there is voltage, check the power supply fuse on the computer. If fuse is okay replace computer.
If there is no voltage, there is a faulty wire(s) or termination(s) between the 9 pin J7 connector and the 9 pin J12 connector.
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 25 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, then the contactor is faulty.
If no voltage is present, check voltage across the two (2) BS2 terminals of the arc suppressor (A.S.) board.
3.If there is no voltage, check voltage across the two (2) AS2 terminals.
If there is voltage across the two (2) AS2 terminals and no voltage across the two (2) BS2 terminals, replace the arc suppressor (A.S.) board.
If there is no 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.
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