Alarm Signals; Control Board Check Procedure; Control Board Replacement - Hoshizaki REFRIGERATED PREP TABLE WITH RAISED RAIL 73168 Service Manual

6. Alarm Signals

In the event of operation outside of normal parameters, the control board identifies the
issue with an alarm signal. The alarm signal and temperature are displayed in 1-second
intervals. For service corrections, see "III.A. Alarm Signals."

7. Control Board Check Procedure

Before replacing a control board that does not show a visible defect and that you
suspect is bad, always conduct the following check procedure. This procedure will help
you verify your diagnosis. Before you begin the diagnostics, verify proper supply voltage
and that the unit is correctly plugged in.
1) Move the power switch to the "ON" position and the rail switch to the "NORMAL"
position. Both cabinet and rail temperatures should be displayed. The perimeter heater,
cabinet fans, and rail fans should be on.
2) If the temperature display is not on, check the 3A 125V fuse on the control board and
the control transformer secondary circuit. Secondary transformer output is 10V at
115V primary input. If the fuse and the secondary circuit voltage are good, but the
temperature display is off, the control board is bad and should be replaced.
3) If the temperature display is on and the components are not energizing, verify
12VDC to the corresponding relay. If there is no voltage to the component relay, the
control board is bad and should be replaced.

8. Control Board Replacement

1) Open the front panel. Move the power switch to the "OFF" position, then unplug the
unit.
2) Remove the wire cover, then remove the control box cover.
3) Disconnect the control board wire connectors.
4) Remove the control board.
5) Install the new control board in the control box taking care not to damage it.
6) Connect the control board wire connectors to the new control board.
7) Replace the control box cover in its correct position.
8) Plug in the unit, then move the power switch to the "ON" position to start the unit's
cooling process.
9) Check the setpoint and service menu settings and verify that they are set to the factory
defaults. See "II.D.4. Controls and Adjustments" and "II.D.5. Service Menu."
Alarm Signals
E1
High Temperature Alarm
E2 Low Temperature Alarm
E3 Defrost Alarm (cabinet only)
E4
Not Used
High Condenser Temperature Alarm
E7
(clogged filter)
E8
Defrost Thermistor Malfunction Alarm
E9
Condenser Thermistor Malfunction Alarm
EA EEPROM Write Error Alarm
ED EEPROM Verification or Read Error Alarm
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