R-291KM - Sharp Home Appliance Service Manual (repair manual). Page 4

R-291(K)M

2 – 1

R218L(W)

Microwave ovens contain circuitry capable of producing very high voltage and current, contact with any part of the high voltage circuit will result in

ltage harness.

1) Disconnect the supply.

2) Door opened, and wedged open.

3) Discharge the high voltage capacitor.

WARNING: AGAINST THE CHARGE OF THE HIGH-VOLTAGE

CAPACITOR

The high-voltage capacitor remains charged about 60 sec-

onds and then short-circuit the connection of the high-
voltage capacitor (that is, of the connecting lead of the

an insulated screwdriver. 

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 3D checks and then disconnect the leads to the pri-
mary of the power transformer. Ensure that these leads remain iso-
lated from other components and the oven chassis. (Use insulation
tape if necessary.) When the testing is completed, carry out 3D  checks
and reconnect the leads to the primary of the power transformer.

1) Reconnect all leads removed  from components during testing.

2) Replace the outer case (cabinet).

3) Reconnect the supply.

4) Run the oven. Check all functions.

Microwave ovens should not be run empty. To test for the presence of
microwave energy within a cavity, place a cup of cold water on the
oven turntable, close the door and set the power level to HIGH
(100%). And set the microwave timer for two (2) minutes. When the
two minutes has elapsed (timer at zero) carefully check that the water
is now hot. If the water remains cold, carry out 3D 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 leakage test
should be carried out.