Part Number STH034 3/12 97
Troubleshooting
Control System
WILL NOT RUN DIAGNOSTICS
1. Verify primary voltage is supplied.
2. Reboot by disconnecting and reconnecting the
main power supply.
3. Verify ON/OFF rocker switch functions properly
and supplies line voltage to relay coil.
4. Verify relay contacts are closed.
5. Verify line voltage is present at the transformer
primary.
6. Verify 24VDC is present at the transformer
secondary.
7. Verify fuse on 24 VDC supply is closed.
8. Verify 24 VDC is present at main control board
MTA2 (J35) connector. Disconnect and reconnect
wiring to verify connection.
9. Evaporator fan, duct fan, cabinet refrigeration or
ice machine operating?
• No - Replace main control board.
• Yes - Go to next step.
10. Display energized?
• No - Inspect wiring, disconnect and reconnect
wiring to verify connection, replace display board.
• Yes - Go to next step.
Continued on next page …
High (line) voltage is present when the back panel is
removed.
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