Panasonic NN-K593MF Service Manual page 22

NN-S453WF
9.3. Digital programmer circuit troubleshooting guide
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, 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, 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 resistance).
If any abnormal condition is detected, replace the defective parts.
No key input
No beep sound
(For NN-S453WF/S553WF)
No beep sound
(For NN-K593MF/K573MF/K573WF/K543WF)
Power relay A(RY-2) does not turn on even
though the program has been set and the
start pad is tapped
(For NN-S453WF/S553WF)
Power relay A(RY-2) does not turn on even
though the program has been set and the
start pad is tapped
(For NN-K593MF/K573MF/K573WF/K543WF)
No microwave oscillation at any power setting
(For NN-S453WF/S553WF)
No microwave oscillation at any power setting
(For NN-K593MF/K573MF/K573WF/K543WF)
Dark or unclear display
Missing or lighting of incorrect segment
H97/H98 appears in window and oven stops
operation. Program High power for 1 minute
and conduct following test quickly, unless
H97/H98 appears and oven stops.
NEW H.V.
CONTINUED FOR SENSOR MODELS
Auto sensor cooking does not operate
normally.
(Steam Sensor cooking does not
detect steam from foods.)
STEP CHECK
1 Fuse pattern of DPC
2 Low voltage transformer (LVT)
secondary voltage
3 Emitter of Q10
1 Membrane switch continuity
1 IC-1 pin 29 voltage
1 IC-1 pin 8 voltage
1 IC-1 pin 9 voltage while
operation
2 Short circuit between collector
and Emitter of Q223.
1 IC-1 pin 41 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 IC-1 pin 39 and pin 45
voltages while operation at
high power
2 Q220 transistor
1 Replace display and check
operation
1 Replace IC-1 and check
operation
1 Unplug CN702(2 pin)
connector and measure
voltage between terminals
2 Unplug CN701(3 pin)
connector and measure pin 3
voltage
1 Steam sensor terminal voltage
by using high impedance
tester (20k Ω/ V),while
breathing on metal surface of
sensor
22
RESULT
Normal
Open (NOTE)
Abnormal 0V
Normal
Abnormal
Normal = 5V
Abnormal
Normal
Abnormal
Normal
Abnormal
Normal
Abnormal
Normal = 5V
Still does not turn on
RY-2 turns on
Abnormal
Normal = 5V
Still does not turn on
RY-2 turns on
Abnormal
Normal=18V
Abnormal
Normal
Abnormal
Normal=18V
Abnormal
Normal
Normal
Abnormal
Normal
Abnormal
0V
AC line voltage of 230-
240V
0V
Approx. AC 3V
Abnormal = 0V Steam sensor
Normal>10-30mV IC-1
CAUSE/CORRECTION
S
STEP 2
Shorted Circuit of
ZNR,L.V.T., Oven
Lamp etc.Replace
DPC
LVT
→ Step 3
ZD10, Q10
Display
Membrane switch
IC-1
IC-1
BZ, Q224
IC-1
BZ, Q224
IC-1
→ Step 2
RY-2
Q223
IC-1
→ Step 2
RY-2
Q223
IC-1
→ Step 2
Q220
RY-1
IC-1
→ Step 2
Q220
RY-1
DISPLAY
IC-1
IC-1
DISPLAY
1. Latch Switch
2. DPC/Power Relay
→ Step 2
DPC
Magnetron