Entertainment Center: TVs, Stereos, VCRs and DVDs - TV vertical sync unstable
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11-04-01, 10:19 PM
I have a sony wega trinitron tv
as soon as the tv is on the picture moves vertically up leaving the bottom blank. And it will slowly come down and again it will go up. and it continues this way
sometime it goes up high enough to put the tv on standby
what is the problem
as soon as the tv is on the picture moves vertically up leaving the bottom blank. And it will slowly come down and again it will go up. and it continues this way
sometime it goes up high enough to put the tv on standby
what is the problem
Smokey
11-05-01, 03:04 AM
Good Morning, takkaru:
You didn't say how old the Sony is but will assume it has a few miles on it.
The vertical oscillator in these sets is a 30 Hz unit and the oscillator is sync'd (locked) on frequency by pulse information on the incoming signal. In short, the signal from the cable/TV Station provides information to your set to lock the picture both horizontally and vertically.
The usual cause of your vertical instability is a bad filter capacitor in the low voltage power supply. This capacitor filters the voltage going to a normally stable circuit to make a clean DC voltage. When the capacitor fails, it allows 60 cycle ripple to appear in the DC voltages. The 60 cycles is from your household AC source (where you have the TV plugged into the wall). The 60 cycle AC in your house is not in phase with the incoming sync information from the TV station and it confuses the Vertical Oscillator. Hence, the osillator will become unstable and the picture will roll.
It's not an expensive fix but requires that back to come off the set, some troubleshooting to occur, and the defective part replaced. Call around and get some estimates
based on what information I have given you.
Smokey ;)
You didn't say how old the Sony is but will assume it has a few miles on it.
The vertical oscillator in these sets is a 30 Hz unit and the oscillator is sync'd (locked) on frequency by pulse information on the incoming signal. In short, the signal from the cable/TV Station provides information to your set to lock the picture both horizontally and vertically.
The usual cause of your vertical instability is a bad filter capacitor in the low voltage power supply. This capacitor filters the voltage going to a normally stable circuit to make a clean DC voltage. When the capacitor fails, it allows 60 cycle ripple to appear in the DC voltages. The 60 cycles is from your household AC source (where you have the TV plugged into the wall). The 60 cycle AC in your house is not in phase with the incoming sync information from the TV station and it confuses the Vertical Oscillator. Hence, the osillator will become unstable and the picture will roll.
It's not an expensive fix but requires that back to come off the set, some troubleshooting to occur, and the defective part replaced. Call around and get some estimates
based on what information I have given you.
Smokey ;)