vertical lines in a Toshiba TV

[Username1]

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Hi!

I guess I picked a good day to see if anything was going on at vk. So for the sharpness
knob causing the lines to be more visible or defined, - I have always thought of the
sharpness as a kind of "tone" control for the picture. You know turning up the tone
and giving the speaker more treble. So you are letting a little more treble get to
the picture tube.... It also confirms what we already know, it's higher frequency
noise, as turning up the treble also makes hiss-noise more noticeable on a speaker.

An Observation - At the edges of the screen on both the right & left it seems
that where the scan lines end it looks a bit brighter - Is it just the picture
artifact, or is it real?

In your scope picture it looks like your scan is 60hz, frame rate, If you set it
to sync to horiz sync and scoped the video amp or any of the color drivers
you are looking at, I think you would see the vert lines in each line scan.
Can you count the ripple on what should be a flat line?

I think if you did that you would find that the interference is a high
harmonic of the horiz output, again we know it.

You may want to find similar bright or dark lines on the tv screen across the entire
face of the screen, count them up, and multiply times 15,734 to see what the
frequency might be, and then use some math and see what inductor & cap.
pair makes a filter close to that frequency and those components may
be the trouble spot..... You know that tv has a LOT of coils in it.

And that voltage source that you have growing on the neck board is another
possible noise injection point. There is probably a focus voltage showing
up on that board to do it's business, and is it possible it's drooling a
few stray electrons around....?

You may also want to do a little unorthodox troubleshooting for this problem....
Take a 1/2" size nut (steel not a squirrel kind of nut) mount it tightly on a
wooden dowel and carefully move it around near all the goodies that can
be a problem area, like the coils, horiz. everything, output, flyback, etc.
Keep a good eye on the tv screen while doing it..... You know that
white screen above with the sharpness turned up. You never know
you may find a spot that changes something.... You might also
try a small magnet on a stick...... (Weak magnet)

This might need to be a 2 person experiment, you know be safe.
You can also do something similar be using a shield around some
components. And even use a 2" wire on a stick touch some
components and give them a little bit of an antenna and
let that item transmit their signal, or noise a little "more"
and see what happens....



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