Craig PC570 blue convergence

[luRaichu]

How to fix? I don’t have the service manual. I’ll try moving the yoke rings and see if I can identify them

[Alex KL-1]

Some small color CRT sets have very large "pixels" (phosphours), blurring fine detais, especially coloured ones. And exacerbates convergence issues.

[Alex KL-1]

BTW, you can experiment with the rings, some are indeed for convergence (some are for purity). But, will be interesting if you take note of it's original position (put some markings in it), for easily resetting if nothing better is achieved. I always mark positions for this complex adjustings.

[zeno]

Mark magnets FIRST, you can go back that way.
Rear ring is purity, front ring usually a locking ring.

Zeno

[jhalphen]

Hi to All,
Hi luRaichu,

Your Craig TV is working fine.

Alex KL-1 is correct, on a 5 inch color CRT (15CAC66X-TC10), "15" is the CRT's diagonal screen size, 15cm, hence 5".
The phosphor pitch is far too coarse for correct reproduction of B&W fine computer text.
In the lower part of your 2nd photo, the text looks OK and you wont get it better by fiddling with the purity/convergence magnets.
Top of photo looks messed up because of interference with the frame rate of the camera used for the photo.

The Craig like hundreds of private label 5" color TVs were relatively cheap small sets with rather low color pitch phosphors.

If you really want good B&W computer text visibility on a small color screen, you have to graduate to fine pitch tubes like the Sony PVM (industrial) or BVM (Broadcast) monitors with Trinitron HR (high resolution) tubes.

Computer monitors with Delta dot triad phosphors have much better resolution than CRTs for TV only, problem is computer monitors don't exist in the 5" size. Smallest i've seen is 9", and 12/13" was the standard for years in the 80s.

Best Regards
jhalphen
Paris/France

[old_tv_nut]

Yes, I see some worse blue convergence at the top and upper right, but I agree with Jerome that there is a likelihood to only make it worse or just push it around to a different part of the screen. I also agree that computer text is an unreasonably critical test.

If you take the attitude that you want to experiment and just accept that you may not improve it, then I would say go ahead, but don't demand of yourself that you will make it perfect. You could luck out or you could be chasing your tail.

[luRaichu]

With enough fiddling, I was able to make the convergence acceptable.


I don't think any of the yoke rings change purity? Those adjustments might be on the neckboard.

[old_tv_nut]

Excellent!