Panasonic NN-GT338MZTE / NN-GT338WZTE / NN-GT338MZPE / NN-GT338WZPE Simplified Service Manual ▷ View online
4.1. Adjustment of Primary latch
switch, Secondary latch
switch and Short switch.
switch and Short switch.
1. Mount the Primary latch swith, the Secondary latch switch
and the Short switch to the door hook assembly as shown
in illustration.
NOTE:
in illustration.
NOTE:
No
specific
individual
adjustments
during
installation of the Primary latch switch, Secondary
latch switch or Short switch to the door hook are
required.
latch switch or Short switch to the door hook are
required.
2. When mounting the door hook assembly to the oven
assembly, adjust the door hook assembly by moving it in
the direction of the arrows in the illustration so that the oven
door will not have any play in it. Check for play in the door
by pulling the door assembly. Make sure that the latch keys
move smoothly after adjustment is completed. Completely
tighten the screws holding the door hook assembly to the
oven assembly.
the direction of the arrows in the illustration so that the oven
door will not have any play in it. Check for play in the door
by pulling the door assembly. Make sure that the latch keys
move smoothly after adjustment is completed. Completely
tighten the screws holding the door hook assembly to the
oven assembly.
3. Reconnect the short switch and check the coninuity of the
monitor circuit and all latch switches again by following the
component test procedures.
component test procedures.
4.2. Measurement of microwave
output
The output power of the magnetron can be determined by
performing IEC standard test procedures. However, due to the
complexity of IEC test procedures, it is recommended to test
the magnetron using the simple method outlined below.
Necessary Equipment:
• 1 liter beaker
• Glass thermometer
• Wrist watch or stopwatch
NOTE:
performing IEC standard test procedures. However, due to the
complexity of IEC test procedures, it is recommended to test
the magnetron using the simple method outlined below.
Necessary Equipment:
• 1 liter beaker
• Glass thermometer
• Wrist watch or stopwatch
NOTE:
Check the line voltage under load.Low voltage will
lower the magnetron output. Take the temperature
readings and heating time as accurately as possible.
lower the magnetron output. Take the temperature
readings and heating time as accurately as possible.
1. Fill the beaker with exactly one liter of tap water. Stir the
water using the thermometer and record the water’s
temperature. (recorded as T1).
temperature. (recorded as T1).
2. Place the beaker on the center of glass tray.
Set the oven for High power and heat it for exactly one
minute.
minute.
3. Stir the water again and read the temperature of the water.
(recorded as T2).
4. The normal temperature rise at High power level for each
model is as shown in table.
TABLE (1L-1min.test)
RATED OUTPUT
TEMPERATURE RISE
800W
Min.12.6°F(7.0°C)
4 MEASUREMENTS AND ADJUSTMENTS
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NN-GT338M / NN-GT338W
5 TROUBLESHOOTING GUIDE
DANGER: HIGH VOLTAGES
1. Ensure proper grounding before troubleshooting.
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 AC is present on 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.
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 AC is present on 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.
Before troubleshooting, operate the microwave oven following the correct operating procedures in the instruction manual in order
to find the exact cause of any trouble, since operator error may be mistaken for the oven’s malfunction.
to find the exact cause of any trouble, since operator error may be mistaken for the oven’s malfunction.
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NN-GT338M / NN-GT338W
11
NN-GT338M / NN-GT338W
5.1. Trouble related to Digital Programmer Circuit
SYMPTOM
STEP
CHECK
RESULT
CAUSE/CORRECTIONS
No display when oven is first plugged
in
in
1
Fuse pattern of D.P.C.
Normal
→Step2
Open
Replace D.P.C. or Fuse
Pattern
Pattern
2
Low voltage transforment (L.V.T.)
secondary voltage
secondary voltage
Abnormal 0V
L.V.T.
Normal
→Step3
3
IC1 pin23 voltage
Abnormal
Q11, ZD11
Normal=3.3V
IC1, CX320, Display
No key input
1
Membrane switch continuity
Abnormal
Membrane switch
Normal
IC1
No beep sound
1
IC1 pin 29 voltage
Abnormal
IC1
Normal=3.3V
BZ210, Q210
Power relay RY4 does not turn on
even though the program had been set
and the start pad is tapped
even though the program had been set
and the start pad is tapped
1
IC1 pin 26 voltage while operation
Abnormal
IC1
Normal=3.3V
→Step2
2
Collector of Q229 voltage
Abnormal
Q229
Normal 0.7V
RY4
No microwave oscillation at any power
1
IC1 pin 1 voltages while operation at high
power
power
Abnormal
IC1
Normal=3.3V
→Step2
2
Collector of Q220 voltage
Abnormal
Q220 and /or Q225
Normal 0.7V
→Step3
3
Short circuit between collector and emitter
of Q220
of Q220
Still not turn on
RY1, Q225
RY1 turns on
Q220
Dark or unclear display
1
Replace display and check operation
Normal
Display
Abnormal
IC1
Missing or lighting of unnecessary
segment
segment
1
Replace IC1 and check operation
Normal
IC1
Abnormal
Display
5.2. How to check the semiconductors using an OHM meter
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NN-GT338M / NN-GT338W
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