John Lewis NN-GT578SBJQ OEM 27L JLFSMWG002 Service Manual page 22

Microwave oven shuts down
between 15 - 33 seconds.
Set the microwave oven to test
mode (See page )
Set to high power 1 minute.
H97 or H98 appears in the dis-
play and the microwave oven
stops working
Program for 1 minute and per-
from the following test
12.7 Checking the semiconductors using a resistance meter
Diode
Transistor
Digital transistor
1 Unplug CN702 connec-
tor and measure the
voltage between the
terminlas
2 Unplug CN703 connec-
tor and measure the
voltage at Pin 1
A K
A K
C
B
E
C
B
E
E
C
B
E C B
22
Abnormal
Normal
Abnormal
Normal
Forward
A - K Low
Forward
B - E Low
B - C Low
C - E
Forward
E - B Low
Low
C - B
C - E
Forward
10 -30 k
E - B
50 -90 k
C - B
C - E 40 -60 k
1. Latch switch
2. DPC/Power relay
Step 2
DPC
1. Magnetron
2. Inverter circuit
Reverse
Reverse
Reverse
Reverse
10 -30 k