Let's talk convergence (WG6100 25")

[Level42]

So,today my uncle and I dived into my friend Luc's SW cockpit monitor. It's a WG6100 that's equipped with a 25" tube.

We came a long way to get it right, but not 100%.

I've watched my uncle closely and combined that with what I read in the manuals and elsewhere.

I start setting the yoke for purity, I have to shift it as far as possible towards the screen to get a nice even color on R.G and B.
Then I fix the yoke with the screw.

Next I select a magenta (red & blue) crosshatch and set the middle set of rings. I can get it pretty close to perfect horizontally and vertically. We are talking about the center area of the screen, the edges need to be done later.

Next I select the white crosshatch and adjust the last set of rings (for green convergence). I can get the vertical and horizontal lines correct in the center of the screen. Everything looks pretty OK BUT I can't get the horizontal green line to match the top part of the screen AND the bottom of the screen.

It's like the green raster is taller than the magenta one because the green line is above the magenta on the top, and below  the magenta on the bottom parts.

I can't understand how that can be. I'm lost.....
 

[MonMotha]

Sounds like you need to "tilt" the front of the yoke on the neck of the tube.  That's the major adjustment for edge/corner convergence; the rings mostly affect center convergence.  Tilting the yoke will also mess up all your other settings fairly nicely, so you'll have to repeat the process.  It's somewhat iterative.  I'm in awe of the "pros" who can do all this in one shot in a couple minutes.

There are usually some rubbery stops inserted between the yoke and the back "face" of the tube to fix it in position tilt-wise.

I've never bothered to do this.  It seems like enough of a pain in the butt for me to just live with slightly "off" corner/edge convergence.

[Level42]

Yes, I tried that but it doesn't help for this. And indeed it messes up al the other stuff again. I've been working on this for a good number of hours now. And started over 3 times....

 If it would only be the corners, I'd leave it. Also, the corners can be adjusted with the little strips with metal I've got. But it's too much in the center of the screen. If you know SW: you'll see it pretty badly (f.i.) at the Insert Coin text. It gives a pretty hallucinating effect.

Could I have a defective convergence ring set ? I don't think so as all the rings have at least some effect....
Could the ring set be too close to the yoke or too far off ?

[Level42]

Pics:

Test frame, a lot sturdier than it looks, really rock-solid




First magenta set-up, pretty decent (don't look at the corners, they're of no concern yet):


Center of the screen, again, not bad at all:



Then I switch to the white crosshatch:


Center of the screen, you can already see the difference starting at the top....


Top of the screen, the green is ABOVE the magenta....:


Bottom of the screen, the green is BELOW the magenta.....:


Resulting in this....:


By the way, these pics clearly show the difference between WG (low res) and Amplifone (mid-res) tubes.....

[Level42]

So, anyone of the monitor pro's know how it can be that the green raster seems bigger than the red&blue ?

[Kevin Mullins]

Last tube swap I did I had the same problem. (it was a 19" though)
I ended giving up on it and might get back to it later or try another tube.
Was starting to wonder if it has something to do with a tube being either 90degree or 100 degree.

[Level42]

And that's what crossed my mind too.

The Amplifone tubes are 90 degree and the WG6100 100.

However, the _same_ yoke assembly is used on the Amplifone 19" and 25" AND the 19" WG6100, right ?

That's pretty weird seeing the difference in tube angle.

Then I thought that it can't be the tube angle because all three color canons are in-line and in the same distance to the screen.
Next thought: I have no problem converging red and blue. This is controlled with the middle set of converging rings. Then the green is the problem. This is controlled by the last set of rings.

Now, suppose there's a difference in the convergence ring-set. This cab was slapped together, lord knows what they did.
Suppose the f.i. the distance between the R-B and G rings is different. I think that _could_ result in the effects I get now.

Maybe the effect is less on a 19" because it's simply smaller.

I'll go and compare the convergence rings now......

[Level42]

Allright, they look different. My 25" Amplifone seems to have rings that are thicker and the outer diameter is larger compared to the one's on the WG6100. Could it be that there's a 19" convergence ring-set on there.....

It may not be so, but it would sound reasonable that a larger CRT needs bigger (more powerfull) magnets.

[Level42]

OK, I got some advice from the vectorlist. I ended up moving the convergence ring set up the neck as far as it can go (touching the yoke). This did decrease the error, but it's still there.

I think in playing, it won't be so noticeable and maybe I just want too much from almost 30 year old equipment. Anybody knows a TV of that age that looks perfect ?

It really isn't half bad when playing the game. Yes my Amplifone is better, but that too still has some convergence errors (which I will hope to fix with some of the "magnetic" strips)....

Anyway, I learned EVERYTHING about convergence now and I totally lost my fear of it. I'm sure I can now fix raster convergence errors,and the next challenge will be replacing Luc's 19" CRT (on his upright SW, yes he has an upright too) which has a burn spot with a brand NOS one.....