Got this email from Mr Raja from India
We got a CRT TV for repair at my work Bench (Samsung 21inch)
There was a power supply problem which we rectified, TV is working fine, but we are getting 3 RGB lines at the top of the screen as shown below in the photo. Changed all the filter capacitors on vertical section I.C used is TDA8356 please let me know the root cause to solve this issue
Note: If we reduce the pump up capacitor value from 22mfd/160v to 10mfd there is a slight improvement which shifts lines to top most but not 100% please suggest to me. I will be waiting for your replay.
Anything on the screen except the 3 lines, is the vertical Vcc supply okay? Find out more suspect components (areas) using the attached fine.
Thank you very much for your valued replay,
Above TV (Samsung 21 inch) problem solved successfully.
Below is the observation made
1. In fault condition checked the fly back voltage 24v at icTDA8356 pin 6 coming via resistor ohms from FBT, saw the waveform below
2.After Replacing 220ohm with 100ohm fly back voltage increased 24v to 30v (dc offset) resulting RGB lines shifted top100% & TV worked fine customer felt very happy on delivery.
Once again thank you very much for your valued support
Awesome Mr. Raja... Thanks