ELECTRIC COMBI OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
BATTERY BACKUP -
PROGRAMABLE CONTROL
The battery backup module allows the SRAM (static ram) to retain the configuration and program information in memory if there is a power loss. The battery backup may come in a two piece configuration of an SRAM chip mounted onto a battery module or a one piece SRAM and battery module combination. The 28 pin
Battery Test
1.Disconnect power from the oven, then turn the power back on.
2.The control board will perform a power up diagnostic test, sound the buzzer and turn the displays and lights on then off.
A.If the displays go blank and lights turn off on the control, then the battery backup is functioning properly.
B.If oven or control will not power up, see “TROUBLESHOOTING” section for a list of possible causes.
C.If code numbers appear in the time and temperature display or the control operation is erratic, the battery backup may be malfunctioning.
1)Press the keypad ON button. If dashes “- -
WARNING: DISCONNECT THE ELECTRICAL POWER TO THE MACHINE AT THE MAIN CIRCUIT BOX. PLACE A TAG ON THE CIRCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.
2)Remove the right side panel as outlined under “COVERS AND PANELS”
3)With the power disconnected from the oven, check the battery module voltage while mounted on the CPU board. Measure the voltage between pins 14 and 28 on the SRAM chip. If voltage is less than 3VDC, then replace the SRAM/Battery module combination (one or two piece) as outlined below in “BATTERY REPLACEMENT” and repeat battery test.
NOTE: SRAM/Battery backup module voltage can not be measured without first being mounted on the CPU board and powered at least once.
NOTE: Do not use a battery backup labeled ISSI on the top. This type of battery backup quickly drains the SRAM resulting in an 888c display error.
3.The oven should now operate properly.
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