Middleby Marshall PS200 series - Manual (Page 16)

15
SECTION 3 - SERVICING COMPONENTS
Figure 16
Current pickup assembly - side view
Figure 17
Current pickup assembly -
end view
D. Controller/Motor Failure
When the conveyor speed controller fails, it is very pos-
sible that a shorted conveyor motor caused the problem.
Unless the motor is changed, the installation of another
conveyor speed controller will simply burn up the new con-
troller.
You are STRONGLY ADVISED to bypass the speed con-
troller and install the tester unit shown in Figure 18 before
replacing any speed controller that has burned out. This
will identify the source of the problem - the speed controller
or the motor. It is much less expensive to burn out the
tester than another speed controller.
The components for this tester can be purchased at any
electrical supply store. The tester is not as accurate or
sensitive as the speed controller, and so should NOT be
left in place on the oven after servicing!
Components needed for the field tester:
•
Full-wave AC-DC bridge, 400V, 4A
• Light dimmer switch, 5A
• In-line 5A AC fuse enclosed in plastic case
• 2 alligator clips
CAUTION: DO NOT turn the conveyor switch ON while
the field tester is connected!
1. Disconnect the motor lead wires and attach to the field
tester as shown in Figure 18. Depending on the oven
model, you can simply use the black and red gear motor
leads, or the remote leads at the terminal block con-
nection.
To reverse the conveyor motor direction, simply inter-
change the black and red leads.
2. To start the test, the dimmer switch should be turned
until the motor begins to operate. The switch can then
be turned down to the desired motor speed.
Figure 18
Field Tester for Conveyor Drive Motor
or circuit breaker