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46 TROUBLESHOOTING
NO
Troubleshooting:
No Display – Screen is Blank
YES
NO
Does the keypad beep when
a key is pressed?
Is wiring from the
control board to the
display OK?
Is pin 1 on the J7
connector receiving 5
VDC? (see schematic,
page 51)
NO
YES
YES
Replace the display
(page A-8).
NO
NO
YES
Is the power supply
output 24 VDC?
NO
YES
YES
Verify 5 VDC is
present on pin 1 of the
J7 connector. If not,
replace the control
board (page A-8).
Is the control board
receiving correct VDC?
Verify voltage on pin 2
of the J7 connector is
24 VDC (see
schematic, page 51).
Replace the fuses.
(page A-5 through A-6)
Check wiring from the
power supply to the
control board. Correct
wiring if necessary.
Replace the control
board. (page A-8)
Correct wiring. If ribbon
cable is damaged, replace
the keypad (page A-5
through A-6).
Is the power supply
receiving power?
Replace the power
supply (page A-5
through A-6).