Hi, I have a Sansui SV118Si TV which after about a minute of being switched on ends up with a Horizontal White Line. I have replaced the Vertical output IC (LA8470). The problem is still there. If I switch the TV off for a few minutes and then back on I get a picture for about a minute. Any ideas on what else I can replace?
In your statement i found during switch on you get picture. Check whether in a few minute picture suddenly goes to the horizontal line or height reduces and then goes to line. If suddenly goes means change any zener diode in pumpup circuit. If it is not means LA 7840 ic getting imbalanced supply voltage i.e.,negative and positive voltage are not equal. Suppose only one vcc means supply resister getting high ohms and change the the supply resister.
Sounds like something is getting hot causing voltage loss or drive pulse loss to the vertical IC. Maybe you have a bad solder joint. Try tapping the circuit board around the vertical section. A capacitor could be heating and opening up. Stargazer Also you might try using circuit cooler spray and make the problem show up.
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