Dacor EF42 Series, Руководство по обслуживанию

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Refer to the table below for typical resistances. The main objective is to locate resistances
that are considerably lower than the values given in the table.
If the low resistance is found to be between pins JP7-15 and either of pins JP7-16 or JP7-17 you will
need to further isolate the source of the low resistance between the two FoodSaver™ assemblies and
the dispenser assembly.
System Control
The control system relies heavily upon digital communication. All components communicate with the
Main Control Board for proper operation. Some components have dedicated inputs to the Main board.
These components will include the door switches, thermistors, and the temperature display selector.
These components return voltage levels to govern the actions of the Main board.
The Display PCB, FoodSaver assemblies and the Dispenser (Fountain PCB) all communicate with the
Main board using serial data communication. Serial data communication allows several components to
use the same input wires for complex operations.
Serial data allows the FoodSaver assemblies to notify the Main board of the current temperature as
well as the desired temperature. The Main Board can then determine the level of cooling needed for the
entire appliance. Requests for ice and water dispensing are sent via the data lines and the appropriate
solenoids are energized.
Loss of communication can result in various faults. If an open or poor connection is at the Main Board,
all communication will be affected. If the open is at the opposite end of a wire harness, only the board
with the loose connection will be affected.
Pin Pin Resistance
JP7-1 JP7-3 1.9KOhm
JP7-5 JP7-7 3KOhm
JP7-15 JP7-16 1KOhm
JP7-15 JP7-17 250Ohm
NOTE
This type of control system poses a challenge to the service technician. Many problems may
go away by resetting the system. A reset can be accomplished by turning off the main power
switch for ten seconds and reinstating power. This can result in a system that cannot be
diagnosed as the fault is no longer apparent. It might be beneficial to do some troubleshooting
before resetting the system to locate an intermittent service issue.
Faults in the data communication system can result in parts of the system not functioning while
others will operate. Determining the location of a fault in the data communication system is a
process of deductive reasoning.
The first step is to verify that the Main Board is capable of sending and receiving data. If
the dispenser works, or the FoodSaver displays illuminate when the door is opened, or the
temperature can be adjusted, the Main Board is capable of sending and receiving data. Do not
replace the Main Board.
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