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Author Topic: WG D9200 color/distortion issues  (Read 2716 times)

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beatter

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WG D9200 color/distortion issues
« on: July 15, 2011, 02:30:29 pm »
I'm having a bit of issues with my WG D9200 (naturally). It's a 27" and the image appears rotated as well as the colors are all off.
I attached an image of the actual monitor as well as the original background so you can see the distortion.

I am a complete newbie to monitor repair and I know pretty much nothing. Any help will be appreciated.
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MonMotha

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Re: WG D9200 color/distortion issues
« Reply #1 on: July 15, 2011, 03:05:16 pm »
Looks like the yoke is loose or got bumped.

beatter

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Re: WG D9200 color/distortion issues
« Reply #2 on: July 15, 2011, 04:50:10 pm »
That would appear to be the problem, or at least part of it. The yoke is definitely loose, but I don't know how to tighten it :/
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MonMotha

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Re: WG D9200 color/distortion issues
« Reply #3 on: July 15, 2011, 04:58:09 pm »
If it is indeed loose, you can probably just turn it.  Turn it counter-clockwise (looking at it from the back of the tube) to correct out that rotation.  The colors will probably come pretty close to what they're supposed to be just with that.

You may want to do this with the power off.  While it's not strictly required, the horizontal winding of the yoke spikes to a couple thousand volts on most designs, and that'll bite if you touch it.

The yokes are usually held in place using some rubber wedges between the yoke and the tube face as well as a screw clamp near the back of the yoke between the yoke and convergence/purity ring assembly.  You may need to loosen this clamp to make the yoke easy to turn.  DO NOT OVERTIGHTEN when setting it back; you could break the glass of the tube neck and destroy the tube.

Corner convergence is affected by the tilt of the yoke (up/down, left/right) wrt the tube face.  You adjust that with the aforementioned rubber stoppers.  Use a grid pattern to check if it needs adjusted and set appropriately.  It's all totally backwards, so it may take a while to get the hang of it.  A friend or a mirror is useful.

Once you've got the yoke set, you adjust purity (any remaining incorrect colors) using the purity rings, then adjust center convergence.  I think Rick Nieman has a tutorial on this somewhere. You may need to loosen the other clamp to adjust these rings.

beatter

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Re: WG D9200 color/distortion issues
« Reply #4 on: July 15, 2011, 05:32:28 pm »
Thanks for the help, I got the yoke adjusted. However, I'm having troubles adjusting the colors. I tried the purity rings, but everything I do to them just seems to make it worse.
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MonMotha

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Re: WG D9200 color/distortion issues
« Reply #5 on: July 15, 2011, 06:08:53 pm »
Did rotating the yoke improve the colors any?  What's the picture look like, now?

beatter

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Re: WG D9200 color/distortion issues
« Reply #6 on: July 15, 2011, 06:21:53 pm »
Yes, adjusting the yoke did help with the colors somewhat.
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MonMotha

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Re: WG D9200 color/distortion issues
« Reply #7 on: July 15, 2011, 06:46:30 pm »
Looks like a classic yoke misalignment/purity issue, but make sure to degauss the hell out of it just to be sure.  Check on solid color screens (red, green, blue, and white) to see what they look like.  It's sometimes easier to figure out wtf is going on that way than with color bars.

http://personalpages.tds.net/~rcarlsen/cbm/converge.txt has a reasonable procedure for adjusting the yoke and setting purity/convergence.  You'll probably also find a line of either ink or glue across the ring set indicating what the factory position was, which is probably a good place to start.

You might also hit up Rick Nieman (PM rickn on the forums).  He can practically do this in his sleep and can probably describe/troubleshoot the procedure better than I can.

beatter

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Re: WG D9200 color/distortion issues
« Reply #8 on: July 15, 2011, 07:32:19 pm »
I discovered the issue, the yoke isn't close enough to the tube, and I can't figure out how to get it closer. Is there some special screw that keeps it closer to the tube?
I know there's the 4 clamps, but those just push away from the tube.
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MonMotha

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Re: WG D9200 color/distortion issues
« Reply #9 on: July 15, 2011, 07:36:05 pm »
If you loosen that back clamp, you should be able to slide it along the neck of the tube.  It's usually held away from the back of the tube by those little rubber wedge stoppers.  If those are out of place somehow (they're usually held in place with adhesive on the back of them), they could be preventing you from getting it close enough.  Once you have it firmly up against those wedges (which are used mostly to adjust tilt), you re-set that back clamp to hold it in place and keep it from rotating.

A picture of your yoke area might help.  I could at least see what you're seeing then, and maybe mark it up.

beatter

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Re: WG D9200 color/distortion issues
« Reply #10 on: July 15, 2011, 08:06:05 pm »
As soon as I started reading your post, I thought "I should probably post a picture of the yoke."

I provided one from the top and one from the side. I think the bolted clamp is what you are talking about, but I am not totally sure.
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MonMotha

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Re: WG D9200 color/distortion issues
« Reply #11 on: July 17, 2011, 01:53:19 am »
The clamp I'm talking about is between the convergence rings and the yoke itself, right below where the wires attach.

It looks like your yoke also features some handy screws or similar to set distance and tilt against the back of the tube.  I'm not sure quite how it works, but it's probably easier to adjust than rubber stoppers.

Also, unplug your rotation coil (the small black coil right around the tube neck) during this testing.  It may cause some erroneous results.  Might as well yank the degauss coil while you're at it, just in case it's malfunctioning.

beatter

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Re: WG D9200 color/distortion issues
« Reply #12 on: July 24, 2011, 10:12:41 pm »
Good News! After plenty of tinkering (and a week vacation) I got it working just right! Hopefully my fixes will last through the move into the cabinet.

Many thanks to you MonMotha, without your help I probably would have had to buy a new monitor.
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