View Full Version : Zenith Convergence


Arcanine
10-08-2015, 01:39 AM
Okay. Well I am pretty much lost and kind of confused at this point. This set has pretty healthy vertical, I've replaced out all the bumble bee caps that it had, and even replaced a few that were questionable. I also replaced the large electrolytic can in the vertical section too, as well as C5.

This set uses a 25LC30 chassis.

I also remember the guy I got it from telling me something about setting the high voltage. I have a probe but I have not checked it yet to see. These run at what? 25kV?

I can get most of the screen converged pretty well, and I can get the purity pretty nice too. I can never seen to get the bottom of the screen to converge completely. If I try and converge the bottom, the top goes all out of whack.

Perhaps it's slightly compressed at the bottom and stretched at the top, but if that's the case, by no means is it as bad as the other set was. I don't see retrace lines on this set at all.

Is there something that commonly goes wrong on these sets that cause these issues?? A drifting resistor, a bad selenium somewhere? A diode that kicks the bucket? A coil? Or this this operator error? IE: I'm not doing the convergence procedure correctly.

Alastair E
10-08-2015, 07:13 AM
Converging a delta-gun set--is sorta an art in itself. There's usually a sequence to follow and the setting-controls are usually numbered--but not always.

Sometimes--with the issues you have, the inability to converge the bottom, (applies to any section of screen where it seems impossible to set) sometimes its needed to mis-converge both top and bottom equally while looking at the middle to get that equally out too--Then reset the Statics to bring it all in together, a slight tweak to top/bottom then to get it perfect--However, you'll find that Other parts, say horizontals will then be out so will need re-touching ...

Even though you've set the statics first off--they often need a little tweak in order to get everything lined up, as the dynamics are altered during set-up.

Your vertical Linearity could also be affecting the convergence--That really needs to be sorted before you converge the set in earnest....

Get the picture as perfect as you can geometry wise, horiz. lin/vert. lin, pincusion, etc and in black/white before worrying about convergence then finally color...

I hope you have a cross-hatch generator to work with--Trying to work with a moving picture is nearly impossible!--Simple, maybe computer-generated image or test DVD with various patterns will be OK....

The convergence coils rely on mixing both vertical and horizontal wave-forms to modulate the position according to the scan point on screen. IF the linearity is wrong--so will be the convergence drive signals to the coils....

Findm-Keepm
10-08-2015, 07:35 AM
I've converged quite a few - the steps are generally:

Degauss
Set purity
Set grayscale
Set R/G/B center convergence using static magnets and Blue lateral assy
Follow steps 1-9 (some have 10 or 11 steps) on convergence panel - left side, right side, top/bottom is generally the order, although some are different.

Zenith convergence is about the easiest, after Quasars, IMHO.

This all requires a bar/dot/crosshatch generator, I assume you have one? If not, using program material is not recommended, but some of the best techs I know can, in a pinch.

Cheers,

Arcanine
10-08-2015, 12:49 PM
I've converged quite a few - the steps are generally:

Degauss
Set purity
Set grayscale
Set R/G/B center convergence using static magnets and Blue lateral assy
Follow steps 1-9 (some have 10 or 11 steps) on convergence panel - left side, right side, top/bottom is generally the order, although some are different.

Zenith convergence is about the easiest, after Quasars, IMHO.

This all requires a bar/dot/crosshatch generator, I assume you have one? If not, using program material is not recommended, but some of the best techs I know can, in a pinch.

Cheers,

Okay so I am doing it correctly then. It has something to do with the sets linearity being a little weird then. I'll see if I can figure out how to adjust the linearity correctly, then try and see if it will accept a convergence better.

I know I have both linearity and height nearly at max on the controls to get a full screen on the image. I'm going to start checking resistors in the circuit and see what I get.

I never try and set to a moving image. I have adjustment patterns I feed though my modulator to the set.

Bill R
10-08-2015, 06:24 PM
I wouldn't spend any time worrying about convergence until you get the height and linearity right.