29
Fault
Probable cause
Solution
Turntable does not work
Photoelectric sensor fault
Motor fault
Main control board error
Replace photoelectric sensor
Replace motor
Replace main control board
Touch screen fault
Resistance broken
No calibration
Main control board error
Replace touch screen
Calibrate touch function
Replace main control board
Garble code on screen
Bad data lines connection
LCD fault
Main control board error
Re
‐
installation the data lines
Replace LCD
Replace main control board
No video show
No video signal
No working voltage
Monitor screen fault
Replace pin hole camera
Check 12V power and its wiring
Replace monitor screen
No response for ‘auto open
door’ function
Exhaust fan is open
Main control board error
No 24V work voltage
Electromagnet fault
Axis of electromagnet decentration
Stop exhaust fan
Replace main control board
Replace power adapter (24V)
Replace electromagnet
Re
‐
mount the door mechanism
Warning :
“Time
‐
out”
No microwave
Wrong microwave power setting
Poor microwave absorb ability
Heating time is short
Check microwave generated components
Set right microwave power
Increase microwave power
Prolong heating time and set multi
‐
step
Warning:
“Temperature error”
Air leakage
Pressure sensor fault
Main control board error
Power is setted too large
Check the air impermeability
Replace pressure sensor
Replace main control board
Set related microwave power
Warning:
‘Pressure limited’
Power is setted too large
Pressure setting value is lower
Samples have good microwave
absorbing ability
Pressure sensor fault
Reduce microwave power
Increase setting value
Reduce microwave power
Replace pressure sensor
Warning:
‘Pressure control’
Lower pressure setting value
Main control board error
Increase setting value
Replace main control board
Warning:
‘Turntable fault’
Photoelectric sensor fault
Main control board error
Turntable motor fault
Replace Photoelectric sensor
Replace main control board
Replace motor
30
TOPEX service manual
4-1 HV components measuring method
Measuring the HV components input or output terminals with the power on is forbidden.These HV
components can be estimated by measuring its resistance.Test behavior can only be operated 5 minutes
latter after power off.
4-1-1 Filament transformer
Disconnect the primary and secondary wiring terminals,the resistance of primary is about 20
Ω
and the
secondary is 1
Ω
normally. If resistance is right, we can eliminate the doubt of filament transformer fault
4-1-2 HV transformer
Disconnect the primary and secondary wiring terminals,the resistance of primary is about 1.5
Ω
and the
secondary is nearly 100
Ω
normally (between secondary and grounding).
Fault type: open circuit
4-1-3 HV capacitor
The resistance between two terminals is about 10M
Ω
.
Lower or higher resistance indicate the capacitor has been break down.
Resistance should escalate while the measuring process, if the resistance is directly fixed at 10M
Ω
, no
escalation process, that indicates the HV capacitor has been break down.
Fault type: Break down
4-1-4 HV diode
Take down HV diode
If no microwave generated and the surface temperature is too high that indicates HV diode has been
break down.
The resistance between anode and cathode is about 30 to 70M
Ω
.
The resistance between cathode and anode is infinite.
If the forward direction resistance is too high or reverse is too low beyond the standard indicates break
down.
The anode must be connected with HV capacitor and reliable grounding for cathode.
4-1-5 Magnetron
Resistance of filament cathode is nearly 1
Ω
.
Resistance between filament cathode and grounding is infinite.
Magnet flaws on magnetron is not allowed.
