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45
TROUBLESHOOTING GCCO-C CONT’D
PROBABLE CAUSE
CORRECTIVE ACTION
Defective control transformer
(12 VAC).
Check transformer for normal operation.
Check primary coil for 120 VAC and 154.1
Ω
. Check secondary coil
for no less than 10.5 VAC and 1
Ω
.
If voltage is measured on primary:
Check for voltage on secondary.
Replace transformer.
If voltage is not measured on primary:
Check wires for any shorts.
Defective rectifier
Check for no less than 10.5 VAC on
TP1
and 5 VDC on
TP2
.
If correct voltage is present at
TP1
and present, but low at
TP2
unplug both ribbon connections from CPU and re-measure at
TP2
.
If voltage remains low at
TP2
replace CPU (40102-311).
If voltage at
TP2
increased to 5 VDC when ribbon was unplugged,
plug ribbon back in to CPU and disconnect from Interface board.
Re-measure at
TP2
.
If voltage dropped to below 5 VDC replace ribbon cable (31110-01).
If voltage remains at 5 VDC, plug ribbon back into Interface board
and measure for 5 VDC at
TP3.
If voltage is present at
TP3
and display is still not on, press and hold
the
R/C
button on board if LED’s come on replace Interface board.
If LED segment does not illuminate or the LED is blank, replace
LED.
Note: Display should now be operating.
Summary of Contents for GCCO-C
Page 29: ...29 GENERAL CONT D ONE PAN TWO PAN THREE PAN FOUR PAN FIVE PAN ...
Page 59: ...59 TECHNICAL DATA CONT D GCCO C TEST POINT LAYOUT TP 2 TP 1 TP 3 TP 4 TP5 TP6 TP7 ...
Page 61: ...61 WIREING DIAGRAM GCCO T ...
Page 62: ...62 WIRING DIAGRAM GCCO AP ...
Page 63: ...63 WIRING DIAGRAM GCCO SII ...
Page 64: ...64 WIRING DIAGRAM GCCO C ...
Page 65: ...65 WIRING DIAGRAM GCCO PP ...
Page 66: ...66 WIRING DIAGRAM GCCO PT ...