LG RF-21FA20 - Trouble Shooting (Screen & Distortion); Heater, Screen, and Waveform Issues; Barrel Distortion Troubleshooting

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Check the heater element
Check & Replace
FR401
Check & Replace
CPT
Check the Heater voltage
Increase the screen
Voltage of FBT
Screen is BlackRetrace line
is visible
Check FBT & CPT
socket & CPT
Check the waveform
at pin21 of IC01
Check the waveform at
pin42~44 of IC01
Check the waveform
at pin14 of IC141
Check & Replace
ICN01
Check & Replace
IC141
Check & Replace
IC01
Check & Replace
CPT PCB Assy
NG
6.0~6.4Vrms0V
Normal
Normal
No
Abnormal
Normal
Normal
No
Check & Replace
IC01
Check & Replace
FR402,D404,IC302
Check the waveform at
pin36 of IC01
Check the waveform
at pin1 of IC302
Check the waveform
at R406
Check & Replace
Q302,Q303
Check & Replace
D401,D402,C405
Barrel Distortion
No
Yes
No
Yes
No Yes
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