Membrane Switch On Control Board Malfunctioning - Sub-Zero 700TC-3 Service Manual

Troubleshooting Guides
PROBLEM
V. Membrane Switch on Control
Board Malfunctioning
W. No Lights
#3758412 - Revision B - December, 2006
Integrated
Integrated
POSSIBLE CAUSE
Control Panel Ribbon Cable
Disconnected or Connected Incorrectly
Control Panel Assembly Defective (OR)
No Signal Read at Control Board
No power to unit
Unit switched OFF
Unit in Sabbath Mode
Defective or loose light bulb(s)
Light Terminator Interrupt / Door Ajar
Light Switch Disconnected or Defective
Lighting System Wiring Disconnected or
Defective
No Power From Control Board
(NOTE: See Unit in Sabbath Mode above.)
8-18
3
3 Series
Series
(700- T ALL)
(700- T ALL)
TEST / ACTION
Check control panel ribbon cable. All Pins
on board should be in ribbon cable terminal
housing. See Membrane Switch/Ribbon
Cable Test Procedures for terminal housing
Pin 1 identification.
See Membrane Switch/Ribbon Cable Test
Procedures. If membrane switch fails any
test, replace entire control panel assembly.
If switch passes all tests, replace control
board.
Check power to unit, plug unit in or switch
supply circuit breaker ON.
Check for "OFF" displayed at LCD. If off,
press UNIT ON/OFF key.
Press UNIT ON/OFF key to OFF.
Install a known good light bulb.
Check for proper door closing. If door is
open too long, lighting system is interrupted
by terminator.
If door is obstructed, move obstruction.
If door does not close properly, see Door
Hinge Operation Test Procedures later in
this section. Replace hinge if defective.
Check wire connections at light switch.
Reconnect/repair. Check for 115V AC to
and from light switch. Replace switch if
defective.
Check continuity from light sockets to control
board (J7-4). Reconnect/repair or replace
defective components.
Check for 115V AC at J7-4 on control board.
Replace board if defective.
(NOTE: See Unit in Sabbath Mode above.)