Troubleshooting Guide - John Lewis NN-GT578SBJQ OEM 27L JLFSMWG002 Service Manual

12 Troubleshooting Guide

1. Do not try to repair the H.V. Inverter power supply. Replace the inverter circuit board as a complete unit.
2. Do not adjust the preset volume on the Inverter. It is very dangerous to repair or adjust without special test
equiptment, the inverter handles very high voltage and current.
3. Do not attempt to measure the voltages in the microwave oven high voltage circuit.
4. Always discharge the high voltage capacitors on the inverter circuit board before troubleshooting.
5. When checking the continuity of the components on the H.V. inverter circuit, unsolder and remove one leg of
the component from circuit board. Checking the continuity of these components when both legs are soldered
into the board may result in a false reading or damage to your meter.
6. When disconnecting 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 components on the digital programmer circuit, this circuit is sensitive to static electricity.
8. When working with the digital programmer board ensure your body is connected to ground to discharge any
static charge.
9. 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.
To ensure the complaint is not due to operator error, check the operation of the oven by following the procedures
explained in the operating instruction book.
Caution
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