Carrier 69NT40-561-300, Operation And Service Manual

Page: 158 / 174

T-365 7–42
Checking the Drive Module:
1. Turn unit OFF.
2. Disconnect the four pin connector to the Stepper Motor.
3. With a voltmeter set to read 24 volts AC, attach the positive lead to the drive module outlet pin A (wire
1A) of the four pin connector and the negative lead to the B pin (wire 1B).
4. Turn ON unit, and watch the volt meter. After a short delay, the reading should rise to approximately 12 volts.
5. Repeat for pins C and D (wires 2A and 2B).
6. If only one set of pins reads a voltage, check connections and retest.
7. If the retest reads out the same, the drive module or controller is faulty.
8. If no voltage is present in any step, the output from the controller to the drive module may be faulty.
Check the connections and wires from the controller to the drive module.
9. To replace the drive module, disconnect all connectors, unscrew from mounting, and replace with a NEW
drive module in reverse order.
7.27.3 Checking the Controller
1. Turn the unit OFF.
2. Disconnect the six pin connector to the stepper drive from the controller.
3. With a voltmeter set to read 50 volts DC, attach the positive lead to outlet pin A of the six pin connector, and
the negative lead to pin B or TP-9 of the controller.
4. Turn ON the unit for 40 seconds, and watch the voltmeter. There should be approximately 24 to 32 VDC
shown on pin A.
5. There should be zero volts on pin B.
6. After a short delay, the reading should rise to approximately 24 to 32 VDC on pin E.
7. Pins C and D will have zero to 5 volts transistor logic (TTL) signals present, however, this can only be
checked with the connector assembled as this is an open collector type circuit. Checking the outputs on A, B
and E will verify that the controller is supplying power to the drive module. To be thorough, and if it is desired,
the signals on pins C and D can be checked as follows:
8. Install a jumper assembly (Carrier part number 07-00408-00) to connect the drive module and controller
connectors as shown in Figure 7.29 .
9. Connect the positive lead of the voltmeter to test connector socket C and negative lead to socket B, and run
as before by resetting unit.
10.Repeat for sockets D and B.
Figure 7.29 Jumper Assembly
There should be approximately five volts DC on sockets “C” and “D” (S1 and S2) when measured as above. If not
the connections or controller is faulty. If any of these pins are not consistent, the connections or the controller is
suspect. Check and replace as required.
A
B
C
D
E
A
B
C
D
E
Controller
Connector (EC) Drive Module
Connector (SD)
Jumper
Test
Connector