R-3A55
TROUBLESHOOTING CHART
WARNING TO SERVICE PERSONNEL
Microwave ovens contain circuitry capable of producing very high voltage and current, contact with any part of the
high voltage circuit will result in electrocution.
REMEMBER TO CHECK 30
REMEMBER TO CHECK4FJ
1) Disconnect the supply.
2) Door opened, and wedged open.
3) Discharge high voltage capacitor.
1) Reconnect all leads removed from components during
testing.
2) Replace the outer case (cabinet).
3, Reconnect the supply-
WARNING AGAINST THE CHARGE OF THE
4) Run the oven. Check all functions.
The high-voltage capacitor remains charged
Microwave ovens should not be run empty, To test for the
1
about 60 seconds after the oven has been I
/ switched off. Wait for 60 seconds and then short-
circuit the connection of the high-voltage capaci- 1
presence of microwave energy within a cavity, place a
cup of cold water on the oven turntable, close the door
and set the microwave timer for two (2) minutes. Set the
tor (that is, of the connecting lead of the high-volt- /
i age rectifier) against the chassis with the use of /
/ an insulated screwdriver.
I
1
Sharp recommend that wherever possible fault-find-
ing is carried out with the supply disconnected. It
may in, some cases, be necessary to connect the
supply after the outer case has been removed, in
this event carry out 30 checks and then disconnect
the leads to the primary of the power transformer.
Ensure that these leads remain isolated from other
components and the.oven chassis, (Use insulation
tape if necessary.) When the testing is completed
carry out 3tJ checks and reconnect the leads to the
primary of the power transformer.
power level to HIGH and push the START button. When
the two minutes has elapsed (timer at zero) carefully
check that the water is now hot. If the water remains cold
carry out 30 checks and re-examine the connections to
the component being tested.
When all service work is completed, and the oven is fully assembled, the microwave power output should be
checked and microwave reakage test carried out
TROUBLESHOOTING GUIDE
When troubleshooting the microwave oven, it is helpful
IMPORTANT: If the oven becomes inoperative because of a
to follow the Sequence of Operation in performing the
blown fuse M8A in the 1st. latch switch - 2nd.
checks. Many of the possible causes of trouble will re-
latch switch - monitor switch - monitor resistor
quire that a specific test be performed. These tests are
circuit, check the 1st. latch switch, 2nd. latch
given a procedure letter which will be found in the “Test
switch, monitor switch and monitor resistor
Procedure”section.
before replacing the fuse M8A.
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