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7. TEST PROCEDURES AND TROUBLESHOOTING
CAUTION
- DISCONNECT THE POWER SUPPLY
CORD FROM THE WALL OUTLET
WHENEVER REMOVING THE CABINET
FROM THE UNIT. PROCEED WITH THE
TESTS ONLY AFTER DISCHARGING
THE HIGH VOLTAGE CAPACITOR AND
REMOVING THE LEAD WIRES FROM
THE PRIMARY WINDING OF THE HIGH
VOLTAGE TRANSFORMER. ( See
Figure 3 )
A. TEST PROCEDURE
COMPONENT
MAGNETRON
Power Level
High (900W)
M-High(750W)
Roast (450W)
Simmer(300W)
Warm (150W)
Low
CHECKOUT PROCEDURE
1) Check for resistance : Across the filament terminals of the
the magnetron with an ohmmeter on Rx1 scale.
2) Check for resistance : Across the filament terminals of
the magnetron and the chassis ground with an ohm-meter
on highest scale.
The chart below shows the firing times of the variable power
relay for the EM-D7750 model. The table should be used as
a means to check the magnetron is operating correctly and
producing any other power setting apart from full power.
On Time/s
(inc.'ramp up' time)
(80W)
Figure 5
Figure 6
% On Time
30.0
100
28.0
93
18.0
60
13.0
43
8.0
27
6.0
20
-5-
Filament Windings
Secondary Winding
Primary Windings
Figure 4
RESULTS
Normal reading :
Less than 1 ohm.
Normal reading :
Infinite ohms
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