Trouble Related To Digital Programmer Circuit - Panasonic NN-H264SFR Service Manual

13.1. Trouble related to digital programmer circuit

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" fuse
patterns are open, please 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" fuse
patterns are open, please replace DPC.
NOTE:* At the time of these repairs, make visual inspection of the varistor for burning damage and
examine the transformer with tester for the presence of layer short-circuit (check primary coil resistanc
If any abnormal condition is detected, replace the defective parts.
No key input
No beep sound
Power relay A(RY-1) does
not turn oneven though the
program has been setand
the start pad is tapped
No microwave oscillation at
any powersetting
Dark or unclear display
Missing or lighting of
unnecessarysegment
STEP CHECK
1 Fuse pattern of DPC
2 Low voltage
transformer (LVT)
secondary voltage
3 IC-1 pin 47 voltage
1 Membrane switch
continuity
1 IC-1 pin 8 voltage
1 IC-1 pin 41 voltage
while operation
2 Short circuit between
pin 8 and pin13 of IC-
220
1 IC-1 pin 22 voltages
while operation at
high power
2 Q220 transistor
1 Replace display and
check operation
1 Replace IC-1 and
check operation
37
RESULT CAUSE/CORRECTIO
Normal
Open (NOTE) Shorted Circuit of
ZNR,L.V.T., Oven
Lamp etc.Replace D
Abnormal 0V LVT
Normal
Abnormal IC-10
Normal = 5V IC-1, CX320, Display
Abnormal Membrane switch
Normal IC-1
Abnormal IC-1
Normal BUZZER, Q224
Abnormal IC-1
Normal = 5V
Still not turn on RY-2
RY-2 turns on IC-220
Abnormal IC-1
Normal
22---5V
Abnormal Q220
Normal RY-1
Normal DISPLAY
Abnormal IC-1
Normal IC-1
Abnormal DISPLAY
STEP 2
Step 3
Step 2
Step 2