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(Trouble 3) Trouble related Digital programmer circuit
SYMPTOM
No display when oven is first plugged in
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
RESULT
Normal
Open
Abnormal
Normal = 5V
Abnormal
Normal
Abnormal
Normal
Abnormal
Normal = 5V
Still not turn on
Ry-2 turns on
Abnormal
Normal
5--- = 5v
Abnormal
Normal
Normal
Abnormal
Normal
Abnormal
CHECK
Fuse resistor R28 1
Ω
Q10 emitter
(Output terminal)
Membrane switch continuity
IC-1 pin 8 voltage
IC-1 pin 41 voltage while operation
Short circuit between pin 8 and pin
12 of IC-220
IC-1 pin 9 voltages while operation at
high power
Q220 transistor
Replace display and check operation
Replace IC-1 and check operation
CAUSE/CORRECTIONS
STEP 2
Shorted circuit of IC-10
Q10
➝
IC-1, CX320, DISPLAY
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
STEP
1
2
1
1
1
2
1
2
1
1
(Trouble 4) Inverter circuit
Inverter PCB Repair Procedures
Warning for High Voltages!
1. Unplug oven when removing outer cabinet.
2. never touch inverter PCB with oven plugged in
inverter PCB handling over 7,000V and it is very danger!
3. Heat sink is also energized with High Voltages!
4. Discharge high voltage before touching circuitry.
5. When testing inverter PCB, completely install it into oven, put outer cabinet and make ground.
1. Discharge high voltage before touching Inverter
PCB.
1. Unplug oven and leave it for more than 30 seconds before
removing outer cabinet.
2. Use insulated lead wire to short across D701 Anode to D702
Cathode or short across magnetron filament terminals to the
chassis ground. Please refer to service manual for detail of the
specified model.
2. Remove inverter PCB from oven before
troubleshooting.
Refer tp related service manual for inverter PCB removal.
1. Visual check:
a. PCB board: Any crack on board, burnt printed copper foil
pattern? Any cockroach, bugs excrements, any mark of wet?
B. Components: Any damaged components? Any burnt, broken or
missing?
How to discharge high voltage capacitors
How to check semi conductor IGBT
