[TinCanAlley]

Originally Posted by vol.2

Yes. The tripler is part of the flyback circuit, which can be the source of the bars. When this journey started, I recommended shielding all of that to see if it went away. Did you ever try that?

Sometimes the bars can couple into the video just from proximity. One test I've done in the past is to make long extension leads between my flyback and the PCB and physically move the whole circuit away from the set and put it inside of a big steel can covered in thick plastic to prevent anything from shorting together. This is really the only foolproof way to eliminate proximity as a source for the bars coupling into the signal. It's dangerous though, so be very careful if you actually try it. I don't know how having an external tripler would effect the situation though. That's lots of high voltage parts to juggle, and the risk of arcing would be high

The important distinction here is that the bars can be one of two things. Either they are a function of the deflection, or they are a function of the video signal (ie they are modifying the actual video information before it gets draw by the deflection system).

The way you see the pulses on the probe is normal in a TV, and they will always be there. The problem is only when they are either coupled into the video signal, or when they are present in the deflection process during scan time. The bars will always be in the deflection during the blanking period and that is normal. Seeing those pulses on a probe is expected and doesn't tell you anything about where the bars are coming from.

Yes, it's normal that adding capacitance across the damper diode could cause a change in brightness. That was only to see if the bars went away, not a permanent fix.

I don't know if it's the way I've adjusted things, but I swear the bars have a more defined edge to them. Almost perfectly smooth and uniformed. I'll have to do more low light scenes and make sure.

I have not figured out a way to shield things without shorting something out. Unless there's a material that can be used as shielding that doesn't conduct, I just know I'll kill something. Is it safe to wrap the anode lead in foil all the way down covering the tripler? The connections on the tripler have black RTV on them, so I don't see an issue on that end.

Would ferrite magnets be of any use? I need one years ago and had to buy 20 of them. They are small and would fit up to 10 ga wire.

As for the tripler, I have an NTE replacement, but that would require ditching the divider and I'm not sure if the NTE is better used as an emergency replacement. I haven't been able to find and OEM one.

Tomorrow I will be scoping the 3rd and 4th video amps. Now I know the settings for the test points from the waveforms in the SM, but if I'm looking for something outside of that, what should I be looking for? AC? DC? Certain time/div? The reason I ask is I've noticed a couple test points that have two different waveforms and each one has a different time/div and produces different forms. I figure it safer to scope all leads on the transistors, but not sure if that's necessary.