CHAMPION USN72 - Manual (Page 68)

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Part 5: BASIC SERVICE
5.3.19 Door Safety Switch Replacement
Refer to Fig. 6.12, A , Part 6, Replacement Parts, for a detailed drawing of the door switch
assembly. The door safety switch assembly consists of a magnet installed in each lift-out door
and a magnetic reed switch mounted in an enclosure beneath the door frame. The door safety
switch prevents the dishwasher from operating if a door is missing or lifted during operation.
To check a door safety switch: Turn power off at the dishwasher control cabinet. Inspect the
door to ensure the magnet is in place and secure. Remove the door switch cover and disconnect
the reed switch leads. Make sure all doors are fully closed. Connect the door safety switch
harness wires together. Turn power on and check if the machine runs normally. If machine
operates, turn off power and replace the door switch. Do not leave the door switch bypassed for
any reason other than testing.
To replace a door safety switch: Turn power off at the dishwasher control cabinet. Note the
orientation of the reed switch. Mark the wires and disconnect. Remove the two (2) retaining nuts
holding the switch. Install the new switch and reassemble in reverse order. Turn power on and
operate the dishwasher. Check the switch operation by carefully lifting the door approximately
1". The dishwasher should stop. Return the dishwasher to service.
5.3.20 Control Circuit Explanation
The following explanation provides background information for Parts 5.3.21 through 5.3.24.
The USN-72/S is a steam heated, 2-tank rack machine. The USN-72/S is to have the following
control features/functions:
1.) Wash down duty motors.
2.) 2 HP wash and rinse tank pumps.
3.) Machine to not function when booster temp. falls below 180
° F.
or to switch to a chemical sanitizing system (supplied by others).
4.) Manual filling of the tanks.
5.) NEMA 4X control box that is remote mounted.
6.) Float tank protection with a 5 second debounce.
7.) 120V control voltage.
8.) Door safety switches.
9.) Rinse saver for potable water conservation.