Panasonic NN-V653WF Service Manual page 32

SYMPTOM
No display when oven is first
plugged in. Oven is dead.
NOTE
Procedure of fuse pattern repairing is as follows:
1. When the fuse pattern (PF2) opens.
(1) Remove the jumper wire (PF1).
(2) Insert the removed jumper wire (PF1) to "(PF2)" position and solder it. If both "PF1" and "PF2"
patterns are open, replace DPC.
2. When the fuse pattern (PF4) opens.
(1) Remove the jumper wire (PF3).
(2) Insert the removed jumper wire (PF3) to "(PF4)" position and solder it. If both "PF3" and "PF4"
patterns are open, replace DPC.
NOTE:* At the time of these repairs, make visual inspection of the varistor for burning damage and
the transformer with tester for the presence of layer short-circuit (check primary coil resistance).
If any abnormal condition is detected, replace the defective parts.
No key input
No beep sound
Power relay A(RY-2) does not
turn on even though the
program has been set and the
start pad is tapped
No microwave oscillation at
any power setting
Dark or unclear display
CHECK
STEP
1 Fuse pattern of DPC
2 Low voltage
transformer (LVT)
secondary voltage
3
IC-1 pin 16 voltage
(Emitter of Q11)
1 Membrane switch
continuity
1 IC-1 pin 29 voltage
1 IC-1 pin 9 voltage
while operation
2 Short circuit between
collector and Emitter
of Q223.
1 IC-1 pin 7 and pin 34
voltages while
operation at high
power
2 Q220 transistor
1 Replace display and
check operation
32
RESULT
Normal
Open (NOTE)
Abnormal 0V
Normal
Abnormal
Normal = 5V
Abnormal
Normal
Abnormal
Normal
Abnormal
Normal = 5V
Still does not turn on
RY-2 turns on
Abnormal
Normal
7---5V
Abnormal
Normal
Normal
Abnormal
CAUSE
CORRECTIONS
STEP 2
Shorted
ZNR,L.V.T.,
Lamp
etc.Replace
LVT
Step
ZD11, Q11
Display
Membrane
IC-1
IC-1
BZ, Q224
IC-1
Step
RY-2
Q223
IC-1
Step
Q220
RY-1
DISPLAY
IC-1