Galanz WP700AP20 - Breakdown Analysis and Means of Overhauling; Examining the Breakdown Causes; Spot Examining Steps of the Microwave Oven

position.
(6) Fix the control panel on the oven (FIG.4-6).
(7) Pług in the terminal plugs of the PC board.
5 BREAKDOWN ANALYSIS AND THE MEANS OF OVERHAULIHG
Before overhauling a microwave oven, you should judge the breakdown and the cause correctly, then you can
repair it with corresponding ways. The overhauling must be proceed in order, any hasty conclusion is not
recommendable, otherwise over-working would be done when repair. The microwave oven may occur compound
breakdown due to all kinds of different reasons, thus, when overhaul, they all should be taken into consideration.
Special attention must be given to the microwave leakage and the electric insulation when examine because they
may do harmful to the repairing staff.
5.1 EXANHNING THE BREAKDOWN CAUSES.
How to examine a microwave oven with breakdown? A better means which demonstrated in practical operating
arę through inspecting and listening. On the basis of large amounts of perceptual knowledge, you can judge and
analysie the break down quickly and correctly.
5.1.1 INSPECTION.
Inspect whether the oven shape is disordered and where is the disordered position, If any. It is normal if the
cabinet disordered a little, but abnormal if the oven, the door disordered, the door hook broken, the door crooked,
or there arę too much looseness between the door and the oven after the door is closed .
5.1.2 LISTENING.
Listening to the sound of the oven operating and the noise of the fan. Minor "wen wen" noise, cycling"kala"noise
and "shishi" noise should be considered as normal. But it is abnormal if the following noises occur:
(1) Sound "wen wen " noise.
(2) Long time "shishi" noise.
(3) Strike sound like "Pipa pipa"
5.2 SPOT EXAMINING STEPS OF THE MICROWAVE
OVEN
5.2.1 EKAMINE THE MICROWAVE INSULATING RESISTANCE
Measure the insulating resistance with a avometer or a
megaohmmeter the value should not be less than 2 megaohms.
Otherwise, part examination should be taken at once. Such as
checking whether the motor, the thermal cutout, the transformer or
the capacitor arę electricity leaking.
5.2.2 EXAMINATION OF THE RESISTANCE VALUE OF THE
MICROWAYE OVEN.
Close the door, set the time (the oven is at operating condition but
the power pług haven't been plugged in ), measure the two feet (L -
N) of the power pług with Rxi grade of an avometer, the resistance value should be about 2.5 ohm. If open circuit
occurs, then you must check whether the 8A fuse is broken> the primary winding of the transformer is open
circuit > the thermal cutout is open circuit or not, you must check whether the interlock device is put through or all
the plugs arę connected well. If short circuit occurred or the
resistance less than 1.5 ohms, you should check whether the
primary winding of the power transformer is short - circuited or part
short-circuited.
5.2.3 EXAMINATION OF MICROWAVE LEAKAGE.
Measure the microwave leakage with a microwave leakage measure.
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Fig. 5-1