CHROMACOLOR II question
 

Anyone know the reason for the lines on the screen of this 1978 Zenith CCII, Model 1983w, 19KC50 chassis?

Lines? I don't see any...

moire'
http://www.google.com/search?sourcei...2370386c77b788

i have had this issue myself.comes from the grid in the crt.i think is called moire.saw a few in the shop days.if it distracting to you,change out the crt.had a customer complain once and purchased a rebuilt crt because of this.i took the crt home and installed it in a philco.looked very good.it didnt bother me.that set looks sharp otherwise

On sets that you can get the focus really sharp, it really brings it out. You could try to compromise a bit at the expense of losing some detail in the picture though...

Thanks for the replies.
I was almost sure it is a moire' effect, but I have never seen it in person, only in photograph plates in troubleshooting manuals.
I have had this CCII in storage for a long time and decided to drag it out and see if it still operates. Don't remember the moire' being there before, but it probably was.
Minus the annoying moire', this old set still produces a picture that made the CCII's legendary.

If it's the lines I think I see, it might be a very protracted vertical foldover. Do the lines move against the rest of the picture if you nudge the vertical hold (or height & centering pots)? If so, change the vertical module or replace the electrolytics on it.

Charles

Charles,

The lines do move against the rest of the picture if I move the vertical hold. Looks like I need to start with replacing some capacitors.

Is there a parts source anywhere for these older Zenith tv's? The volume pot. is a slider and has reached the end of its life - I have been able to set it to an acceptable level by tapping it lightly - but it definately needs replaced.

Thanks,

Robert

When I can find some spare time, I think I will set this CCII on top of the Chromacolor 600x 25DC56 console I picked up and do a comparison of the two sets. The color picture produced by the CCII is stunning - I wish I could photograph it without the picture looking washed out - it would be nice to get the same or near same picture on the console.

See if you can find a Zenith part number for that slide control-should be in the Sams if you have it. I know I have some RCA sliders but not sure about Zenith-somebody probably has one.

The contol will have a 63- prefix, or 063- prefix under the LGE parts system. Alps and Noble made most of the slide controls for Zenith, and suitable replacements are still available from both. Lotsa websites with LGE parts.


Cheers,

I may have that vertical module... I got rid of most of my Zenith module stock, so no promises. But before you replace the module, try this: Pull it from the chassis, and take a dental pick, or something slightly thicker than a sewing needle, and tighten the little contacts on each module pin by carefully poking them inward toward the middle of each contact. Don't over-bend them, though. Wipe a bit of tuner/contact cleaner on the male module connectors on the chassis, and reinstall the module. This may take care of it if it's a cold connection. If not, there are a few electrolytic caps on that module, which you can check for "open" with an ESR meter if you have one, or just replace all of them. The last and least likely problem could be that one of the vertical output transistors is leaking. On that chassis, I think they're on a separate heatsink above the vertical module, and are a pair (NPN & PNP), and I've seen those cause the problem on rare occasions. Freeze spray is a quick test to see if those transistors are failing.

If all else fails, post the module number and I'll look into what I might have.

Charles

The spacing of the phosphor triads is designed to minimize moire if the vertical height is correct - check if you have too much height. Otherwise, as stated above, the strength of the effect depends on the focus being really sharp. If you turn the focus, you can probably move the worst effect from the sides to the center as the optimum focus area changes.