Watlow QPAC - Manual (Page 24)

24 QPAC User's Guide Appendix
Appendix
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. The problem
may be with the QPAC's control card, transformer or power base. Use this
QPAC Troubleshooting Guide to assist with troubleshooting.
Symptom Probable Cause Corrective Action
No output Fuses blown Check and replace fuses
Incorrect input
wiring
See “Input Wiring,” Chapter 2.
Incorrect input
signal
Check temperature control output.
Input signal reversed See “Input Wiring,” Chapter 2.
Input signal not
adjusted
See “Bias and Gain Adjustment," Chapter 3.
Wrong or missing
control card
See “Input Wiring,” Chapter 2.
Transformer wiring Check transformer connections.
Missing load wiring See “Power and Load Wiring,” Chapter 2. The
SCR(s) will not function without a load.
Heatsink temperature
exceeded 86°C (187°F)
Clogged or non-
operational fan
Check fan, power, and clean if necessary. Check
for shorted thermostat, replace fan or ther-
mostat as necessary. #27-0005 thermostat is
normally open and closes on temperature rise.
Transformer hot Incorrect trans-
former
Check product and transformer labels.
Uncontrolled output
full on
Bad control card, or
bias and gain out of
adjustment
Unplug control card, try again. Readjust bias
and 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 it.
Unbalanced output
(QPAC-32 and QPAC-33)
Incorrect phase
rotation
See "Phase Rotation Adjustment," Chapter 3.
The QPAC Service Manual is available at http://www.watlow.com/downloads/
en/manuals/qpacse_a.pdf .
Troubleshoot
QPAC Troubleshooting
Guide.