I have posted before about the Admiral 20Y4E chassis. Last post I made seemed to be ignored. I guess it's because it's about a common:boring: mid 50s set and not interesting enough to you guys.:sigh:

Anyway I solved my integrator problem and my horizontal current problem and had a weird problem that happened as it played.It would do it at times more than others but never a half hour without doing it. What it was doing was the vertical would shrink ever so slightly and the picture would seem to jump when it did it.It was not power surge changes in the line voltage as it was pretty obvious when when my refrigerator came on and it did the old shrink from all sides for a split second.

Anyway I was set to try to tackle this problem somehow yesterday afternoon. was gonna even make a youtube video of the problem and it played perfectly from yesterday afternoon until midnight last night when I turned it off and went to bed.I watched it like a hawk. Not a flicker no matter what.:wtf::confused: Would be no problem if I was keeping this set as I would tackle it if and when it came back but this tv's new home will be a 3 hour drive away.:worried:

The only other problem is a ticking sound from the hv tube socket area but it is constant and doesn't vary any at all to cause this and in fact doesn't seem to cause any picture interference whatsoever.I even turned off the lights and can't see any corona anywhere.I think it's either the socket or the wire breaking down somehow.

Intermittent problems can drive you nuts. I have had a couple of minor problems heal themselves before, and I never did figure out the cause.

Who knows, maybe it was a transformer or other component that finally dried out completely from the heat of normal operation. Or some tiny crumb of solder finally dislodged. Or some gunk or a tiny whisker inside a potentiometer finally cleared up. Or, or, or . . . .

If you can't reproduce the problem, it's hard to suggest any cause of action, other than playing it for a long, long time before delivering it to your faraway friend.

Phil Nelson

I would at least address the ticking HV. Take the cage off and listen again. Still there? make sure the are no sharp/pointed connections that could arc over or spots on the wiring-insulation. Problems like that can only get worse and may cause other breakdown problems that you would want to avoid.

Well it did it again a few times in the first half hour I had it on tonight and then stopped again.I had it on a letterbox format tv show and it actually increases in height slightly and goes back not decreases in height.

At first I thought maybe the height control itself was doing it but tapping on it or the linearity control had no effect. Maybe once did I see it jump when I tapped the vertical output tube but it could have been a coincidence.Couldn't get it to repeat.It did it a couple of times afterward and then stopped again.

From what I've seen once the set gets good and hot it stops doing it.It's been recapped of course but not the micas. There is one mica in the vertical where the sync enters the oscillator.Wonder if that might have something to do with it?

On the ticking problem I think it might be the hv socket cap breaking down somehow or the hv rectifier filament wire. Can't see any corona from the connections. I have one of those mechanics mirrors with the handle on it and held it in back of the upright chassis where the connections were and turned off the lights and couldn't see anything.

I remember an old timer in the business of TV Radio repair sharing his tip on tackling intermittents. He would base what component is creating the poblem based upon how quickly the component warms up.

It would go something like this when the problem occurs and disappears:

Vacuum Tubes first five minutes.

Resistors five to fifteen minutes.

Capacitors fifteen minutes onwards.

Transformers half an hour and onwards.

Does anyone else remember this rule of thumb or something similar? (I was told this about 40 years ago and I believe this is roughly it).

Therefore, if the intermittent problem occurs within the first few minutes, I would first try substituting the vertical oscillator or output tubes. If that doesn't work, I would then start looking at the resistors.

On the other hand, if the problem is apparent when switching the set on and it disappears in 15 minutes or so, I would go after an intermittent capacitor.

From what you have indicated, it sounds like a capacitor is partly open when cold and as the set warms it fixes itself by thermal expansion. Perhaps a little freeze spray on the prime suspect might also help route out the culprit?

Cheers,

Terry

I was thinking freeze spray on some components.the trick is to keep it off the tubes.Kinda scared it might accidentally hit a tube and crack it.:worried::eek:Not used to using freeze spray on tube type equipment.

Anyway here are some screen shots from it.The first ones I've posted since recapping and repairs.

Most of the candidates for freeze spray would be under the chassis, so no danger of squirting the tubes there. If you want to spray above the chassis, just hold a rag or piece of cardboard between the sprayer and nearby tubes.

Phil Nelson

Penthode is on the right track as far as suspecting parts based on the time it takes for heat to effect them on a tube set. Some of the parts you may be looking at are not candidates for freeze spray. It just don't work all the time. I would bet on a cap breaking down at a certain voltage. Screen grid cap in the vertical output or a cap across the yoke. Since you recapped it its possible you got one with poor voltage ratings, or its just going bad. Parts can go bad new as well as old. It might also be a good idea to look at just how close all the leads are on the parts you put in, a little dust across leads too close can be the trouble. Intermitants can also be tracked by hitting individual parts with a wood dowel. And most frustrating it will take time to track down....