1958 Zenith picture adjustment.

[classicradios]

Hello everyone,
I need some help with this Zenith TV from 1958 I think. You can see in the picture the right side of the screen bends inward slightly leaving a black vertical space. I don't know what to adjust to correct it or is this a CRT issue? The chassis # is 15A26. I've worked on 1940's sets before but never one of these high tech "Modern sets"
Thanks for any suggestions.
Jim

[Eric H]

Insufficent horizontal width, isn't there a width control somewhere back there.

Could be a weak Horiz output or Damper tube also, or not enough B+?

Have you tried rotating those centering rings on the back of the yoke yet?

Not the CRT

Eric

[Eric H]

I'll hazard a guess that since it's a Zenith you haven't recapped it and it's running this well on it's original parts?

Typical of zenith that they usually work pretty well as-is.

[classicradios]

Thanks for the suggestions Eric,
I haven't been able to find any width adjustments. The horizontal output and damper tubes test strong on my triplett tube tester. I don't have any spares to try in their place. The TV has received all new caps in the recent past, The electrolytics are original. Adjusting the centering rings didn't help either. Any other ideas?
Jim

[Big Dave]

Change the electrolytics. The bars on the sides look like hum bars. Get all power supply lytics and any in the sweep sections, better yet, change them all.

[Tony V]

Hi Jim,
This particular model Zenith has a special coated metal sleeve that wraps around the crt neck between the yoke and the neck. Check and make sure its still installed. If it is, you loosen the yoke and slide this sleeve in or out to give the correct horizontal width. You should see this sleeve just barely peeking out between the centering rings on the yoke and the neck of the crt. If you dont see it, pull the yoke off and see if its pushed in too far. I racked my brain for the longest time on mine until i found out that this sleeve is used for the horizontal width adjustment. Some people who dont know what this sleeve is for dont install it back on the crt after having yoke off or replacing the crt and then end up with insufficient horizontal width. Kind of weird but all of these have them. Hope this solves your problem.
Tony

[classicradios]

I adjusted the metal ring with no luck. I can't get it any wider. sliding the metal ring towards the centering rings only makes the problem worse. At least now I know where the width adjustment is on these 50's sets, Thanks! I'll change out the electrolytics today if I have time.
Stay tuned.
Jim

[kc8adu]

if the edges are crawling like a snake(bend that travels slowly from bottom to top) it is the lytics.causes the b+ to be low.

[classicradios]

Thanks to all for the help.
Turns out the trouble was with the centering rings. I only adjusted one of the rings before, didn't notice there were 2. Duh,,
Both tabs were turning together originally. Once the rings were moved separately the picture centered and is fine now. I did change all 7 electrolytics. I notice these 1950's sets like to roll and require a slight turn of the vertical hold knob every now and then. Once adjusted my 1940's sets rarely if ever roll, Why is that?
Jim