Part # MCOSM06 Rev 1 (11/03/08) Page 89
Problem Possible Cause Corrective Action
No display A. No power to smart
board
B. No power to relay board
A. Check for 24VAC between pins 1
and 3 on smart board. If voltage
present check for 24VAC at pins 1
and 3 at relay board
B. Check for 24VAC into relay board
and 24VAC out of relay board
between pins 1 and 3 on relay
board
Fan runs for a period
of time, shuts down
then comes back on
after several minutes
A. motor has tripped on
internal thermal
overload
A. check for a minimum 6” clearance
at rear of unit to a wall or heat
source
B. Check air intake vents on back of
motor for obstructions
C. If problem persists and above have
been corrected replace motor assy
Timer slow counting
down A. Timer is in hours / min A. Refer to operations manual or
bulletin # B-19-2001 on how to
change from hour / min to min /
seconds
Temperature out of
calibration A. 400 series controllers
B. 200 & 300 series
controllers
C. Potentiometer defective
A. Confirm oven cavity temp with
resistance chart. If out by more
than 20 Ohms replace probe
B. Calibration can be performed by
repositioning temperature dial.
C. Check for proper ‘sweep’ on
potentiometer. 0 to 10.25KOHMS
RESISTANCE vs. TEMPERATURE CHART FOR INTERNAL OVEN
TEMPERATURE SENSOR
The chart below will provide the Ohms at various temperatures. This will enable
you to determine if the temperature probe is operable.
The chart is degrees Fahrenheit.
TEMP 0° 10° 20° 30° 40° 50° 60° 70° 80° 90°
0° 932 953 974 995 1016 1038 1059 1080 1101 1122
100° 1143 1163 1184 1205 1226 1247 1267 1288 1309 1329
200° 1350 1370 1391 1411 1432 1452 1472 1493 1513 1533
300° 1553 1574 1594 1614 1634 1654 1674 1694 1714 1733
400° 1753 1773 1793 1813 1832 1852 1871 1981 1911 1930
500° 1949 1969 1988 2008 2027 2046 2065 2085 2104 2123
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