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TROUBLESHOOTING GUIDE
WARNING:
CERTAIN PROCEDURES IN THIS
SECTION REQUIRE ELECTRICAL TESTS OR
MEASUREMENTS WHILE POWER IS APPLIED TO
THE MACHINE. EXERCISE EXTREME CAUTION AT
ALL TIMES.
IF TEST POINTS ARE NOT EASILY
ACCESSIBLE, DISCONNECT POWER, ATTACHTEST
EQUIPMENT, AND REAPPLY POWER TO TEST.
This section provides a guide for troubleshooting and
covers some of the more common problems with the
equipment. Servicing personnel need to become familiar
with the circuit aid the components in order to be able to
also follow a logical sequence of troubleshooting and
repair malfunctions not mentioned in the following
paragraphs.
The instruments necessary for troubleshooting are:
A. A.C. Voltmeter to measure line voltages up to 480
volts.
B. A.C. Ammeter to measure line currents up to 160
amps for 208 volt, 1-phase model.
C. Accurate thermometerto measure oven temperature
up to 500°F.
In the following paragraphs, the voltmeter is used to
measure the voltage between 2 phases on 208, 240,
440, 480 volt and between 1-phase and neutral on
220/380 and 240/415 volt supplies. Do no! measure the
voltage to the chassis ground.
For the sake of
simplicity, when the measured voltage is referred to as
208 volt, it is assumed that the supply is 208 volt. When
supply is 240 or 220, the measured voltage should also
be 240 or 220. It is also assumed that the voltage rating
of the oven matches exactly (within the allowable
supply tolerance) that of the field supply. Refer to the
appropriate wiring diagram.
With the main power and oven circuit breakers ON, the
master switch turned to the ON position, and the oven
door closed, the following conditions may occur:
PROBLEM
CORRECTION PROCEDURE
No blower. No heat.
Depress oven light switch or turn timer knob to "0" position, if light comes
on and buzzer sounds, follow Step B; if not, follow Step A.
A. Measure voltage between leads 42 and 48 of master switch. If 208
volts, measure voltage across 21 and 22. If 208 volts, check for bad
connection to switch terminal. If no voltage, check for tripped 15-amp
breaker or bad connection to the breaker.
B. Turn load control to HI. If load control indicator light is lit, check Mower
or motor relay. If indicator light is not lit, depress auxiliary fan switch, if
blower comes on, door switch needs to be adjusted (see PARTS
DESCRIPTION AND REPLACEMENT in this manual). If not, check for
proper connections to door switch on leads 12,13,14.
Blower is ON (with auxiliary
fan switch de-energized), but
no heat.
Turn thermostat knob to about 350°F. If oven indicator light is lit, follow
Step B; if not, follow Step A.
A. Measure voltage between the phases on load side of contactor. If 208
volts exist, check heating elements or connecting leads. If no voltage,
check voltage on supply side of contactor. If 208 volts, contactor is bad.
If no voltage, check main circuit breakers and supply voltage.
B. Check voltage on contactor coil terminals. If 208 volts exist, but
contactor does not pull in, contactor is bad. If no voltage, check voltage
across terminals HI and H2 of toad control switch. If 208 volts, look for
bad connection on leads 60 and 61. If no voltage, check load control
switch.
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