Thursday, December 24, 2015

21 inch CRT Samsung Television with 3 RGB lines at the top of the screen problem now solved.

Got this email from Mr Raja from India

Hi sir,
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
Please go through the picture for your understanding

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.

Hi Raja,
Anything on the screen except the 3 lines, is the vertical Vcc supply okay? Find out more suspect components (areas) using the attached fine.

Regards Humphrey

Hi sir,
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

Thanking you.

Awesome Mr. Raja... Thanks


  1. Hello sir,
    I need help in my TV problem. My TV (PHILIPS Eye-Fi Series) 21 inch. My TV first problem display center of display single white line of horizontal in few days. Now totally off in TV. I check FUSE, Capacitor and transistor in power supply part. No use and not work TV. How to rectify and what device change?

  2. my 21 inch crt tv 3rgb line top of the screen and bottom side 1/2 inch is black and verticle ic is la78040b please give me possible solution

  3. check out this link on how to solve this problem.

    Regards Humphrey

  4. when i adjust the b+ voltage decrese rgb line shifted 100% .