28
QPAC User's Manual
Appendix
Symptom Probable Cause Corrective Action
No output Fuses blown Check and replace fuses
Incorrect input wiring See “Input Wiring,” p. 18-23.
Incorrect input signal Check temp. control output.
Input signal reversed See “Input Wiring,” p. 18-23.
Input signal not adjusted See “Bias and Gain Adjustment"
p. 25-26.
Wrong or missing control card See “Input Wiring,” p. 18-23.
Transformer wiring Check transformer connections.
Missing load wiring See “Power and Load Wiring,”
p. 14-17. The SCR(s) will not
function without a load.
Heatsink Clogged or non-operational fan Check fan, power, and clean if
temperature necessary. Check for shorted
exceeded thermostat, replace fan or thermo-
187°F (86°C) stat as necessary. #27-0005
thermostat is normally open and
closes on temperature rise.
Transformer Incorrect transformer Check product & transformer
hot labels.
Uncontrolled Bad control card, or bias and Unplug control card, try again.
output full ON gain out of adjustment Readjust bias & gain.
Bad transformer Unplug transformer wire and
try again.
Bad power base If full ON or half ON output
present with no control card
and no transformer, power
base is bad, replace.
Unbalanced Incorrect phase rotation See "Phase Rotation Adjust.,"
output p. 25.
(QPAC-32
& QPAC-33)
QPAC Troubleshooting
A technician can isolate a system problem by first checking if the load is good,
and the line voltage and temperature signals are present and correct. If the
above is true, then the power control may be the problem. This problem may
be with the QPAC's control card, transformer or power base. Use Table 8 to
assist with troubleshooting.
The QPAC-33 has four LEDs for diagnostic indication. During normal opera-
tion, all four LEDs will be illuminated.
• Power ON Yellow LED is ON when power is applied to the control.
• Phase Loss Yellow LED is ON when all three phases of line voltage
are present. LED will be OFF if one phase is low or lost.
• Phase Rotation Yellow LED is ON when correct voltage phase exists,
even when load is not wired. LED will be OFF when two
phases are rotated, and when one phase is missing.
• Phase Lock Loop Yellow LED is ON when phase lock loop circuit is
synchronized. LED can go OFF from noisy power line or
if the phase synchronizing circuitry fails. Check power
quality, then repair or replace power base.
QPAC-33 Diagnostics
Troubleshoot
Table 8-
QPAC Troubleshoot-
ing Guide
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