Panasonic NN-A750WB, Service Manual

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12 Troubleshooting guide
Caution
1. Do not try to repair this H.V. Inverter power supply. Replace as a whole unit. When returning the inverter unit pack in the orig-
inal inverter box.
2. Do not adjust the preset volume on the H.V. Inverter. It is very dangerous to repair or adjust without sufficient test equiptment,
this circuit handles very high volatge and current
3. Ensure a good ground connection before beginning any troubleshooting
4. Be careful of the high voltage circuit and take necessary precautions when troubleshooting
5. Discharge the high voltage capacitors on the inverter.
6. When checking the continuity of the switches on the H.V. inverter, disconnect one lead wire from these parts and then check
the continuity with the AC plug removed. To do otherwise may result in a false reading or damage to your meter. When dis-
connecting a plastic connector from a terminal, you must hold the plastic connector and not the lead wire, otherwise the lead
wire may become open circuit.
7. Do not touch any parts of the circuitry on the digital programmer cicruit, since static electric discharge may damage this con-
trol panel.
Whilst working on this board ensure that that your body is connected to ground to discharge any static charge.
8. 240 VAC is present on the digital programmer circuit. (Terminals of the power relays and the primary circuit of the low voltage
transformer). When troubleshooting, be cautious of possible electric shock.
Before troubleshooting, operate the microwave oven following the correct operating procedures in the instruction manual in order to
find the exact cause of any trouble, since operator error may be mistaken for the ovens malfunction.
Troubleshooting (No Operation)
Figure 1