Chromacolor II vertical pincushion adj.?

[N9ZQA]

Is there an adjustment for vertical pincushion on a Chromacolor II? I recently received a RCA dot-bar generator and have been trying it out. My 25KC45 has a 'bow' at the top (center is lower than the outer edges) - the bottom and sides are perfectly straight. Googled it but didn't come up with anything.

-Jim

[jpdylon]

I can't remember if its on the chassis or convergence board. - but there is one.

It will either be a pot with a plastic philips insert or a hex slug.

The adjustment is a little quirky, and if adjusted incorrectly will make the set appear to have a shorted turn (vertical trapezoid) Make small adjustments will looking at the top and bottom on a crosshatch. You should be able to dial it in well enough that it looks correct at 4 feet or further.

[N9ZQA]

Thanks!

I'll take a look tonight and see what I can come up with. The convergence isn't too bad now, but I've got to open it up anyway and chase another problem, so while I have the back off I might as well try it.

-Jim

[kx250rider]

Is yours an inline tube? I can't remember if the K series was the one that went inline, and used a SysIII type video output module while still keeping the ChroII chassis... I know they had a hard time with the convergence and pincushion on those early inline Zeniths.

If that's what yours is, I might suggest leaving it alone if the convergence is OK. It would almost definitely mess with the convergence if you adjust the vertical pincushion.

Charles

[sampson159]

if you have the vertical chassis,there is a pincushion adj on the left side of the flyback.kind of sticking out of the top.you wont have to turn it much.it wont harm convergence.my cc11 had similiar trouble and the adj took care of it.it looks very good except for some blue on the left side that wont converge enough.very slight problem and at a distance of 8 feet,it is unnoticible.also the top and bottom convergence may be off due to misadjusted height and linearity.some of those pots get carbon deposits and be careful when you turn them.it should come out good for you,after all,it is a zenith!!!

[drh4683]

which chassis is yours?

As a helpful note, now that DTV has gone into effect you can take your converter box and set the aspect ratio to 16:9. Some even have a 14:9 ratio, which is especially useful for setting the yoke and adjusting the pincushion dead on.

Alot of times when I used a crosshatch generator, I think it looks good then put the set back together. I then sit down, watch something on that TV and a letterbox scene appears and it looks distorted, or sometimes the pincusion has a dip on one side at the top and is quite annoying. So from now on, I just use a televised signal to set those parameters and it works great everytime.

[N9ZQA]

Thanks to all that responded!

The chassis is 25KC45; it's a delta-gun tube. I've been meaning to re-converge it for a while. The center convergence is great; only the edges are out a little on blue (a result of trying to fudge it to minimize the convergence error at the top). All sides except the top are nice and straight; the bow in the top is noticeable only when watching something in letterbox, or a baseball game with the score ticker at the top. I think that's the same problem you mentioned, Doug.

Didn't get to tear into it last night but will probably open it up here in a few minutes and see what's going on.

-Jim

[N9ZQA]

Just opened it up and found the slug in that coil is firmly glued in place.

Have to run out and do some errands; hopefully will get to investigate further tonight.

-Jim

[drh4683]

opps, didn't realize you mentioned the chassis when you started this thread.