Diagnostics and Troubleshooting
UNT-SVX041D-EN
87
Replacement Checklist
Circuit Module Replacement
1. Circuit modules are equipped with nylon standoffs
which can either be removed by squeezing the barbs at
the rear of the control panel, or squeezing the latch
above the circuit module. If the latter method is chosen,
the standoffs will be retained on the metal panel. The
new standoffs (affixed to the replacement modules)
can be removed if necessary, so the new module circuit
board can be attached to the retained standoffs.
2. If replacing the VelociTach motor control board, special
care should be taken to avoid electro-static discharge
damage. Please use an ESD protection wrist-strap and
frequently touch a grounded surface (with unit power
off) to discharge any static buildup.
3. Replace connectors carefully onto the appropriate
board.
4. Ensure that the new VelociTach motor board controller
is configured to match the configuration label that is
present on the unit. It is necessary to configure the
VelociTach board to avoid improper operation of the
unit, discomfort to the end user, and loud fan
operation.
5. Ensure that the CSTI adapter board switches are set
correctly, as indicated in the unit schematic (where
applicable) shown in
.
6. After replacing modules, commission the unit by
performing at a minimum,
Application Notes
The ECM motor has some notable differences to
traditional designs.
NOTICE
Equipment Damage!
Failure to follow these instructions could result in
equipment damage. The motor harness attached to the
single plug to which the motor mates contains the
115V motor voltage jumper; the motor harness should
always be present for 115V units and should not be
modified or substituted.
Ensure that motor nameplate voltage is the same as
unit voltage (for 3-phase/ 4-wire units with Neutral,
motor voltage will be L-N, not L1-L2).
Ensure that motor harness is correct (harness will have
jumper installed for 115V units only).
Ensure that configuration on the VelociTach motor
control board matches the affixed label.
Maintain correct plug/motor association. The plugs
will have the motor number and shaft configuration
printed on an affixed label.
Ensure that configuration of switches on CSTI adapter
board matches depiction of switches on the unit
schematic.
Ensure that all wires are plugged in securely.
Ensure that edge protection on sharp edges,
grommets, and wire management devices are
maintained when replacing components.
Ensure that blunt-tip screws are used when in the
proximity of wire harnesses.
Figure 62.
Remove PCB
Depress latch to
remove PCB, leaving
standoff attached to
metal panel
Figure 63.
Configure VelociTach board
Figure 64.
Ensure CSTI adapter board switches are set
correctly
