Part # MCOSM06 Rev 1 (11/03/08) Page 61
470 Series Controller
(Thermostat, display and relay board)
Turn the oven on, oven should heat to set temperature within
30 minutes. Press the temperature icon and the temperature
can be viewed above 100 degrees F. If the oven does not
heat, ohm out the probe, at room temperature the probe
should read about 1,000 ohms. Ohm the probe at the faston
connection. See chart under Probes in section four for other
resistance readings. If the probe reads an open or short,
replace the defective probe.
The heat demand relay K1B should be energized when
heating the oven and opened if it is not calling for heat. Look
at the heat LED CR1 on the relay board, the LED will be lit
when the controller calls for heat. Check the door switch if the
heat does not activate. Upper door switch is for heat.
The fan can switch from low to high speed. Look at the fan
LED on the relay board (CR3 LED for high and CR4 for low
speed), the LED will be lit when the controller calls for either
fan. If the operator cannot switch from one fan speed to
another, check the keypad. If the light switched on the display
from one fan speed to another but the fan did not change
speeds, check the relay board. If the display switched and the
fan went o, check the fan itself.
If the keypad does not respond, check the keypad. As
outlined in bulletin B-107-2201
If the encoder does not adjust the temperature check, from
idle press the set function key and adjust the encoder,
the display should change accordingly. If not, change the
encoder.
471 Series Controller
(Custom conguration of the 470 series)
Follow the steps for the 470 controller.
475 Series Controller
(470 version controller with proles)
Follow the steps for the 470 controller.
CONTROLLER FAULT FINDINGUnless otherwise stated the faults and trouble shooting are
the same for all controllers.
DISPLAY FAULT
Does not apply to 200 and 300 series.
Display does not light up
Check the incoming voltage to the oven
Check for 24 volts AC voltage on pins 1 and 3 of the 15-pin
connector
If both check out ne the control board is defective
Display does not change.
Is the colon ashing? If yes, the controller is in hours and
minutes not minutes and seconds. Enter programming to
change the time. If no, disconnect the power for 2 minutes
and reapply power and try to change the time.
If the display still does not change the control board is
defective.
Display reads….
"Auto" The controller is in auto cool. The fan will continue to
operate until the cavity temperature cools to below 150°F.
Then the control will turn o.
"Cool" The controller is in cool. This will happen if the cool
down key is depressed and the door is opened to the rst
door switch only.