vertical lines in a Toshiba TV

[old_tv_nut]

Wild thought - try connecting something like a 0.1 microfarad 400 volt capacitor from green output collector to ground and see if it attenuates it. That woud tell you if it's coming through the video circuits somehow.

[zeno]

Design flaw ? NO WAY !
If you got a scope. Set to display a BLANK, not even snow pix.
Be sure the G-2 is set proper. Color level at zero.
Look at the @200V should be clean. Same with the 3 video outs.
There almost HAS to be crap on them.
Check the E of the 3 outs for garbage also. Trace back.
There is a little PS that runs the EXT for isolation, Check that.
There is an "IF mute". didnt trace but probably turns off IF's when
on ext..
Dont forget the blanking stage also for a look-see.

Zeno

[vol.2]

Yes, I have a scope. I have already scoped the power supplies and the video. Didn't see anything fishy.

Originally Posted by Username1

.
Hi - The lines on the screen line up perfectly to point to a horizontal drive pulse, or
possibly a harmonic, or ringing etc. I don't think it's injected anywhere, but it may
be on the power supply lines, any of them. Do you have a scope? You may need
one to find this.

Yes, I had come to this conclusion already. That's why I said the pulse is strongest right after the horizontal refresh.

I would look at each of the voltage source for this 1/15734
or multiple showing up on voltage source lines. All these sources are also
providing bias for the picture tube, & it's drivers, so if it's in the power
supply, you can bet it's in the tube when no picture is present to begin
with, and it's still there with picture information. So set your scope
to capture several H pulses possible set sync to the H pulse,
and look for itsy bitsy H frequency ripple in the power supply.

They were all clean when I checked. I can see the flyback pulses, but nothing that looks like it would be happening during scan time.

Originally Posted by zeno

Design flaw ? NO WAY !
If you got a scope. Set to display a BLANK, not even snow pix.
Be sure the G-2 is set proper. Color level at zero.
Look at the @200V should be clean.

It's 178V. I can see the flyback pulses in it, but they are outside of scan time. Nothing like the ripple or otherwise bars I see on the screen.

Same with the 3 video outs.
There almost HAS to be crap on them.

Don't see anything.

Check the E of the 3 outs for garbage also. Trace back.

The emitter? Not sure if I did that.

There is a little PS that runs the EXT for isolation, Check that.

Are you talking about the optical input chip's isolated ground?

There is an "IF mute". didnt trace but probably turns off IF's when
on ext..
Dont forget the blanking stage also for a look-see.

That's a little bit above my head. I would need more explanation to grock it.