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How to fix horizontal white lines across entire screen on JVC crt tv

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aliman1

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Hello, I have a JVC AV-36D500 it's about 11 years old, just recently it went on the fritz. The screen had reduced width and horizontal white lines across the entire screen. I checked the main board for any visable problems, I noticed two capacitors had slight bulging on top, they were located on the low power side. One was 100 uF/160V, the other was 470uF/200V, i replaced both caps and that solved the reduced width problem, but I still have horizontal white lines across entire screen. I don't have a service manual so I'm kind of shooting in the dark.
If any one can help me, it would be wonderful.
 

Usually lines which covers parts of the screen are two types:

1)- Lines usually cover part of the screen but not whole screen.
mostly caused by a fault on the vertical circuit, particularly capacitors ESR gone high, need to replace capacitors.

2)- Retrace lines on the CRT screen refers to horizontal lines which covers the whole screen from top to bottom but they are never straight.

Retrace lines they may be caused by the:
-blanking circuit
Faulty capacitors, faulty IC circuits.
-G2(screen) voltage set too high
try to adjust the screen knob on the TV's flyback transformer to lower the screen voltage.
sometimes if the screen voltage increases alone it could point to fly back transformer.
-RGB amplifier supply too low
it could point to the filter capacitor for that line being faulty.(replace the electrolytic capacitor)

- - - Updated - - -


Most of the TV problems were due to the failure of power supply electrolytic capacitors (due to heat) in the primary and secondary section. Capacitorshave a high ESR which can make power supplies malfunction. Typical value electrolytic capacitors in the primary side are 47 and 100 micro farad 50 Volt, but you may encounter also some 2.2-10uF/50-63V.
So in order to eliminate all the influences need to change small electrolytic capacitors in the primary section of the power supply. For more info try to post some picture of the component side PCB in the power supply area/flyback transformer area.
 
Last edited:
I adjusted G2 and the retrace lines are gone. Thanks for your help mister_rf
 

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