Trane CVHE Troubleshooting Manual page 56

Table 5
UCP2 Stepper Module Test Point Voltage Limits
Connector
J2 -(1 to 2) or (3 to 4)
J2 -(1 to case) or (2 to
case)
TP2: 5V to ground
TP4: 24V to ground
TP3: 14V to ground
TP1: 35V to ground
If any of the voltages are out of range, there is a malfunction on the Stepper Board.
The majority of these malfunctions may be diagnosed by using . The ones marked with an
asterisk have been seen in the field before:
Table 6
UCP2 Stepper Module Troubleshooting
Condition(s)
Voltage at Test Points
TP1-TP4 on Stepper
module
Motor winding
Resistance check Pin
to conduit Motor does
not move.
Voltage at Test Points
TP1-TP4 on Stepper
module
Motor winding
resistance check pin
to pin fails.
Motor does not move.
CVHE-SB-32A
VAC
20.4 to 33.12 VAC
10 to 17 VAC
0 VAC
0 VAC
0 VAC
100m VAC to 72m VAC
Possible Problem
Wiring between
Stepper module and
actuator motor is
shorted to ground.
Wiring shorted
together inside
conduit between
Stepper module and
actuator motor.
VDC
0 VDC
13.12 to 21.81
VDC
4.8 to 5.2 VDC
23.2 to 25.1 VDC
11.45 to 15.75
VDC
26 to 48 VDC
Possible Cause(s)
1. Wire insulation
bared inside conduit.
2. Wire insulation
bared or pinched
inside motor junction
box.
Insulation bared.
(Solution(s)
1. Seal wire or run new
wire through conduit.
2. Seal wire, or restrip
and rewire motor
junction box. See Table
4 for wiring diagram.
Seal wire or run new
wire through conduit.
See Table 4 for wiring
diagram.
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