Watlow QPAC Modular SCR Power Control Service - Manual (Page 25)

WATLOW QPAC Service Manual 25 Troubleshooting, Chapter 5
Q33
The QPAC Transformer or Resistor Fuse (R10) is Bad
Check for AC voltage present at the transformer (T1), see Page 35 for trans-
former wiring. Be extremely careful! High voltage is present on the transformer
connections. If no voltage is present, verify that the resistor fuse is good by mea-
suring across R10. You should be able to visually determine whether or not the
fuse is bad. It should read a minimal voltage of < 1V. If it reads open circuit line
voltage, R10 is bad. See Page 5 for ordering a replacement transformer.
The QPAC Mother Board is Bad
Check the DC voltages at the J1 connector. Place the voltmeter common on pin
7 or 8. They should read as follows:
J1 Connector Label Without Card With BF, AF or AL
Test Point Card Installed
1 T STAT Not Used 3 to 5V
2 -V -11 to -14VDC -15 to -22VDC
3 FWZ* +5VDC Pulses +5VDC Pulses*
4 +V 15 to 18VDC 15 to 18VDC
5 Q32, connected to Pin 1
Q01 or Q33
Not Used Not Used
6 +5V 5V ±0.1V 5V ±0.1V
7 COM
8 COM (meter common)
9 KEY
10 COM
11 +LED Not Used Pulses possible
12 COM
*See scope picture on Page 15.
The Phase Loss LED is Not ON
Any one or a combination of phases are low (20% or greater). Measure the
incoming voltage on L1 and L2, L2 and L3, and L3 and L1.
Incorrect Phase Rotation (Phase Rotation LED is Not ON)
The phase rotation must be L1 - L2 - L3. Reverse any two “L” leads and try
again.
The Phase Lock Loop (PLL) is not synchronized with the AC Line
(PLL LED is Not ON)
There is probably noise on the AC line. Check the incoming power with a scope
and try a different power source.
The Zero Cross or Phase Angle Jumper is in the Wrong Location
Move the jumper. See the Zero Cross Calibration procedure on Page 15.
The Unit is Calibrated for the Wrong Frequency
The Zero Cross Calibration procedure must be performed at the operating fre-
quency (50 or 60Hz). See this procedure on Page 15.