Zenith 25EC58 Restoration Thread

[vol.2]

Originally Posted by TinCanAlley

I'm starting to think the jailbars are coming from some other source (IF?).

Random jailbars in the raster is one of the very most difficult things to figure out.

From what I've been able to gather in my quest to solve jailbar problems in my own sets is the following:

1. They can be caused by missing shielding. Sometimes there were big metal shields covering things like the flyback or other noisy sections of the chassis, and they go missing during the life of the set
2. Sometimes grounding problems can cause them. This can also be caused by a missing ground that was completed by a shield or a poor connection on the tube itself or elsewhere.
3. In many cases, the jailbars were always there, and the reason you are seeing them is because newer components are somehow accentuating their visibility. I have been told by people more experienced than me that this can be due to fast, better performing parts passing through more of the bars. I would assume that this is a frequency related effect where the edges of the bars would have originally been smeared together more, and now your fancy new parts are allowing more high frequency information through and it's simply showing the edges of the bars that always there more clearly.

In the last case, my approach has been to look for a place that changing a value could potentially reduce that a little bit. Basically to create a low-pass filter in the exact spot where the jailbars are being introduced.

I haven't had a lot of success with it yet though, so YMMV. I know just enough here to understand people's suggestions, but I don't have a strong enough background in electronics to do much innovating.