DOWNLOAD Panasonic NN-S650WF Service Manual ↓ Size: 2.03 MB | Pages: 28 in PDF or view online for FREE

1. Check grounding before checking for trouble.
2. Be careful of high voltage circuit.
3. Discharge high voltage capacitor.
4. When checking the continuity of the switches or the high voltage transformer,disconnect one lead wire from these parts and

then check continuity with the AC plug removed. To do otherwise may result in a false reading or damage to your meter.
When disconnecting a plastic connector from a terminal, you must hold the plastic connector instead of the lead wire and
then disconnect it, otherwise lead wire may be damaged or the connector cannot be removed.

5. Do not touch any parts of the circuitry on the digital programmer circuit, since static electric discharge may damage this

control panel.
Always touch yourself to ground while working on this panel to discharge any static charge in your body.

6. 220V/240V AC is present at the shaded area          of the digital programmer circuit (Terminals of power relay’s and

primary circuit of low voltage transformer). When troubleshooting, be cautious of possible electrical shock hazard.

1.

Oven is dead.

Fuse is OK.

No display and no operation at all.

2.

No display and no operation at all.

Fuse is blown.

3.

Oven does not accept key input(Program)

4.

Fan motor turn on when oven is

plugged in with door closed.

1. Key input is not insequence

2. Open or loose connection of membrane key pad

    to DPC (Flat cable)

3. Shorted or open membrane key board

4. Defective DPC

1. Misadjustment or loose wiring of secondary

    latch switch

2. Defective secondary latch switch

1. Off-alignment of latch switches

2. Open or loose connection of high voltage circuit

    especially magnetron filament circuit

NOTE: Large contact resistance will bring lower

magnetron filament voltage and causing

magnetron to lower output and/or be in-

termittent.

3. Defective high voltage component

    HV Inverter Power Supply (u)

    Magnetron

4. Open or loose wiring of power relay B (RY-1)

5. Defective primary latch switch

6. Defective DPC or power relay B (RY-1)

1. Open or loose wiring of secondary latch switch

2. Off-alignment of secondary latch switch

3. Defective secondary latch switch

1. Decrease in power source voltage

2. Open or loose wiring of magnetron filament

    circuit.(Intermittent oscillation)

3. Aging change of magnetron

1. Shorted primary latch switch

Check fan motor when thermal cutout is defective.

Check adjustment of primary, secondary latch

switch and short switch including door.

First of all operate the microwave oven following the correct operating procedures in order to find the exact cause of any trouble.

SYMPTOM

CAUSE

CORRECTIONS

Refer to operation procedure.

Refer to DPC troubleshooting.

Adjust door and latch switches.

Adjust door and latch switches.

Check high voltage component according to com-

ponent test procedure and replace if it is defective.

Refer to DPC troubleshooting

Adjust door and latch switches.

1. Open or loose lead wire harness

2. Open thermal cutout (Cavity)

3. Open low voltage transformer

4. Defective DPC

1. Shorted lead wire harness

2. Defective primary latch switdh (NOTE 1)

3. Defective short switch (NOTE 1)

4. Defective Inverter Power Supply (U) (Page 18)

NOTE 1: All of these switches must be replaced at the same time.

Check continuity of power relay (RY1)’s contacts (between 1 and 2) and if it has continuity,

replace power relay B (RY-1)’s.

5.

Timer starts count down but no microwave oscil-

lation.

(No heat while oven lamp and fan motor turn on)

6.

Oven can program but timer does not start count-

down.

7.

Microwave output is low. Oven takes longer time

to cook food.

8.

Fan motor turns on and turntable rotates when

door is opened.

Consult electrician

- 16 -

- 17 -

7.

8.

9.

10.

11.

Oven does not operate and return to plugged in

mode as soon as start pad is pressed.

Loud buzzing noise can be heard.

Turntable motor does not rotate.

Oven stops operation during cooking.

Oven returns to plugged in mode after 10 seconds

elapses on the Auto sensor cooking mode.

1. Defective DPC

1. Loose fan and fan motor

1. Open or loose wiring of turntable motor

2. Defective turntable motor

1. Open or loose wiring of primary and secondary

    latch switch

2.Operation of thermal cutout

1.Open or loose wiring of sensor terminal from

   DPC

2.Open steam sensor

3.Defective DPC

Check tighten screws on escutcheon

base bracket, D.P.C. board.

Adjust door and latch switches.

This oven is programmed with a self diagnostics failure code system which will help for troubleshooting.  H97, H98, and H99 are the provided failure

codes to indicate magnetron and inverter circuit problem areas.  This section explains failure codes of H97, H98, and H99.  First, you must program

the DPC by pressing Clock , Time , Start , Micro Power.  Program unit for operation.  H97, H98, H99 appears in display window a short time after start

key is pressed and there is no microwave oscillation.

NOTE: DO NOT try to repair this Inverter

Power Supply (U) and also DO NOT
RE-ADJUST PRESET VOLUME on
the board.  It is very dangerous to
repair or adjust without sufficient test
equipment because this circuit han-
dles very high voltage and very large
current.  Off alignment of inverter
board operation is dangerous.
Operating a misaligned Inverter cir-
cuit is dangerous due to the very high
voltage and current that is produced
by this board.  Defective boards must
be replaced with a new one.

*   Check magnetron filament for open or short
    to casing before proceeding to determine a
    good magnetron.

Check inverter control signal at
CN701, pin 1 and 2

H97, H98, or H99 appears in display
window

Check magnetron filament continuity

Check Inverter input AC voltages at
CN702

H.V. Inverter (U)
(SEE NOTE)

Magnetron*

DPC board
Loose relay wiring

DPC board

unplug CN701 and measure at
lead wire harness side

refer  to  componenet  test
procedures

unplug CN702 and measure
at lead wire harness side

AC3V

OK

AC 240V

Open

OV

OV

NOTE:  After check, unplug unit to reset to normal operation mode.

H97, H98, H99 appears in display window a short time after start key is pressed and no microwave oscillation with AC Ampere

meter used for troubleshooting

C h e c k   m a g n e t r o n   f i l a m e n t
continuity

H97, H98, or H99 appears in display
window

Check  oven  input  AC  amperes
measure at oven plug

STOP!
If all the above are
OK up to this point,
there may be a H.
V. Inverter problem
(SEE NOTE)

DPC board
Loose wiring

Magnetron*

refer  to  component  test
procedures

more than 0.5A

OK

less than 0.4A

Open

NOTE:  If filament is opened,
AC input Amperes 0.5 to 1A
will flow

NOTE: DO NOT try to repair this Inverter

Power Supply (U) and also DO NOT

RE-ADJUST PRESET VOLUME on
the board.  It is very dangerous to
repair or adjust without sufficient test
equipment because this circuit han-
dles very high voltage and very large
current.  Off alignment of inverter
board operation is dangerous.
Operating a misaligned Inverter cir-
cuit is dangerous due to the very high
voltage and current that is produced
by this board.  Defective boards must
be replaced with a new one.

*   Check magnetron filament for open or short
    to casing before proceeding to determine a
    good magnetron.

- 18 -

SYMPTOM

No display when oven is first plugged in.

Oven is dead.

CAUSE/CORRECTIONS

STEP 2

Shorted Circuit of ZNR,

L.V.T., Oven Lamp etc.

Replace DPC

LVT

➝

 Step 3

ZD10, Q10

➝

 Step 4

IC-220

➝

 IC-1, CX320

STEP

1

2

3

4

CHECK

Fuse pattern of DPC

Low voltage transformer (LVT)

secondary voltage

IC-1 pin 8 voltage

(Emitter of Q10)

IC-1 pin 10 voltage

(15 pin of IC-220)

RESULT

Normal

Open (NOTE)

Abnormal 0V

Normal

Abnormal

Normal = 5V

Abnormal

Normal

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 resistance).

If any abnormal condition is detected, replace the defective parts.

SYMPTOM

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

Missing  or  lighting  of  unnecessary

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.

RESULT

Abnormal

Normal

Abnormal

Normal

Abnormal

Normal = 5V

Still not turn on

RY-2 turns on

Abnormal

Normal

5---5V, 15---5V

Abnormal

Normal

Normal

Abnormal

Normal

Abnormal

0V

0V

Approx. AC 3V

CHECK

Membrane switch continuity

IC-1 pin 31 voltage

IC-1 pin 32 voltage while operation

Short circuit between pin 6 and pin

16 of IC-220

IC-1 pin 38 and pin 39 voltages while

operation at high power

Q220 transistor

Replace display and check operation

Replace IC-1 and check operation

Unplug CN702(2 pin) connector and

measure voltage between terminals

Unplug CN701(3 pin) connector and

measure pin 1 voltage

CAUSE/CORRECTIONS

Membrane switch

IC-1

IC-1

BZ, IC-220

IC-1

➝

 Step 2

RY-2

IC-220

IC-1

➝

 Step 2

Q220

IC-220, RY-1

DISPLAY

IC-1

IC-1

DISPLAY

DPC

Magnetron

STEP

1

1

1

2

1

2

1

1

1

2

NEW H.V.

- 19 -

AC line voltage of 120V

2.  DPC/Power Relay

1.  Latch Switch

➝

 Step 2