LG CF-21Q20EH Service Manual page 13

Check the heater element
Check the Heater voltage
0V
Check & Replace
FR401
Normal
Check & Replace
CPT
Normal
Check the waveform at
pin42~44 of IC01
No
Check & Replace
IC01
Barrel Distortion
No
Check & Replace
IC01
FR402,D404,IC302
NG
6.0~6.4Vrms
Increase the screen
Voltage of FBT
Retrace line
is visible
Check the waveform
at pin21 of IC01
Normal
Check & Replace
CPT PCB Assy
Check the waveform at
pin36 of IC01
Yes
Check the waveform
at pin1 of IC302
No
Check & Replace
No
Check & Replace
Q302,Q303
- 13 -
Screen is Black
Check FBT & CPT
socket & CPT
No
Check the waveform
at pin14 of IC141
Normal
Check & Replace Check & Replace
ICN01
Yes
Check the waveform
at R406
Yes
Check & Replace
D401,D402,C405
Abnormal
IC141