sharp tv with flyback lines on screen repaired

The display of the tv is as shown above.
Voltages on blue and red cathode on tube base is 180v except for the green cathode which is low at 27v

Thought initially that the 15k resistor that supplies the green cathode is bad but on testing it I detect it was good

After some minutes of serious troubleshooting I detect that the drive transistor of value F421 is bad.I changed it and the fault clear away.

I wanted to change the whole of the tube base before I decide to troubleshoot the fault,this help build the skill of a repair technician.This is the tv working perfectly.

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