Test And Checkout Procedures And Trouble Shooting; Test Procedures - Sears 721.81622600 Manual

TEST AND CHECKOUT PRECEDURES AND TROUBLESHOOTING
- CAUTIONS -
- DISCONNECT THE POWER SUPPLY CORD
FROM THE WALL OUTLET WHENEVER
REMOVINGING THE CABINET FROM THE UNIT.
PROCEED WITH THE TESTS ONLY AFTER
DISCHARGING THE HIGH VOLTAGE CAPACITOR
AND REMOVING THE WIRE LEADS FROM THE
PRIMARY WINDING OF THE HIGH VOLTAGE
TRANSFORMER. (SEE FIGURE 25)
- ALL OPERATIONAL CHECKS WITH MICROWAVE
ENERGY MUST BE DONE WITH A LOAD (1 LITER
OF WATER IN CONTAINER) IN THE OVEN.
A. TEST PROCEDURES
COMPONENTS
MAGNETRON
(Wire leads are
removed)
HIGH-VOLTAGE
TRANSFORMER
(Wire leads are
removed)
NOTE: A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS
SERVICED FOR ANY REASON.

TEST PROCEDURES

1) Measure the resistance: Across the
filament terminals of the magnetron with
an ohm-meter on Rx1 scale.
2) Measure the resistance: Between each
filament terminal of the magnetron and
the chassis ground with an ohm-meter
on high test scale.
1) Remove the wire leads.
2) Measure resistance.(ohm meter scale: Rx1)
a. Primary winding
b. Secondary winding
c. Filament winding
3) Measure resistance.
(ohm meter scale: Rx1000)
a. Primary winding to ground
b. Filament winding to ground
Normal reading:
Less than 1 ohm.
Normal reading:
Infinite ohms.
NOTE: Replace the magnetron, if the
magnetron checks and all of the
high voltage component tests are
good, but the unit still does not heat
a load.
Normal readings:
Approx. 0.3 to 0.5 ohm.
Approx. 65 to 120 ohms.
Less than 0.1 ohm.
Normal readings:
Infinite.
Infinite.
7-15
Figure 25
RESULTS