Samsung CT20F3FNT Service Manual page 29

Troubleshooting
5-2 No Video (Sound OK)
Check RK,GK,BK
Signal
Nornal
Check the
Voltage of heater
Nornal
Check
CRT and FBT
Check/Replace
IC201S
5-2
Abnormal
Check R,G,B
Signal into CRT
PCB
Abnormal
Check/Replace
R421,R422,D505
Abnormal
Check IC201S
Pin 51,52,53
(R.G.B)
Check IC201S
Pin 49(BCL-IN)
Pin50(IK)
Abnormal
Check
CRT and FBT
Nornal
Abnormal
Abnormal
Nornal
Nornal
Check IC501
B+(180V-B)
Check the
resistance of R420
Nornal
Check/Replace
D812,FBT
Nornal
Re-Adjust
Screen Voltage
Abnormal
Replace
R420
Samsung Electronics