First Tube and Yoke Swap

Vongoosewink

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So for the last couple months I've been stopping in to my local Goodwill and Salvation Army stores every couple weeks, armed with the 'Donor TV List' from Junknet. Lately the TVs have been getting harder to find at Goodwill, but the Salvation Army had a mess of them. I was happy to score a $5 Zenith SD1915W, which was supposed to be a drop-in replacement for a WG K4603, and I was sure I had this monitor in my Magic Sword game, with bad screen burn.

So I get home, strip this sucker apart, and get ready for a super-easy tube swap. Yeah!

Just to be sure, I check the yoke readings and compare them to my monitor -- they are way off. What the hell??? So I check the monitor again, and discover with a lot of disappointment that it is a WG K4903, not K4603. Bummer. But I was all psyched to swap the tube, and I decided to try it anyway!

Here are a couple pictures, of the TV before and after the tube was removed.
 

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I knew I wasn't going to be able to use the yoke, so I got in there and tried to get it off the tube.

I could not find a decent tutorial on this anywhere, so I was pretty much in the dark. I'll recount what I did, if anyone has an easier method, please let me know for next time. First I used a sharpie to draw a line down the adjustment rings, so I didn't get them too messed up. Then I loosened the screws that held the metal clasps on the whole assembly, so I could get it off. Doesn't budge. I see that it has what looks like a layer of tape or clear plastic material between the rings and the neck of the tube, and the rings are basically stuck to this like glue. I get out an exacto knife, slide the very tip in between, and pry each stuck component loose all the way around the tube. Once these are all loose, the whole thing comes off really easy.

I do the same with my burned monitor. Then I swap the tubes, and put the monitor's yoke and convergence rings on the new tube. I get it all set up, outside in my driveway 'just in case' with a fire extinguisher nearby, and flip the switch. The game screen comes up, but it looks terrible. The colors are all messed up. I checked the forum and saw an old thread where a guy had the same problem, and it turns out my new yoke was too close to the tube -- I pull it out about half a centimeter, and the colors look 100% better! The convergence is off a bit, and there is a big blue splotch of color all along the left side of the screeen. But I'm getting there!

Here are some pictures.

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I opened a test menu and got a grid pattern on the screen, and after 5 frustrating minutes I was able to get the convergence nearly spot-on.

A big thanks here to the mighty Modessitt, and his simple directions on this thread:

http://forums.arcade-museum.com/showthread.php?t=208570

I'm sure without them I'd still be down there fiddling with this thing!

So, I have 2 things I still need help with...

1. The Blue Splotch. Is this a gauss problem, or something else? I don't own a de-gaussing coil, hopefully I'll be able to get this tuned up without one.

2. A more minor issue, it looks like I have horizontal 'racing stripes' coming off the graphics on my screen. Basically, lines of lighter tone coming off to the left of everything. I call them 'racing stripes' as it makes all the graphics look like they are zooming to the right (hope that makes sense!) Pictures attached to further clarify. Anybody know what causes this effect?

Thanks in advance for any help, the monitor is looking better than these crummy pictures show, I'll post some new (hopefully better) once once I get these last 2 problems sorted out.

Note, the picture below is flipped, so the blue is on the right.

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Anybody have any ideas on what I can try to get rid of the blue splotch and the horizontal stripes?
 
Anybody have any ideas on what I can try to get rid of the blue splotch and the horizontal stripes?

The blue could be a magnic on the tube that you may not need for that yoke. most of the time it is a arrow looking shape glued to the tube or also see if it goes away when you turn the monitor left or right.. or does it change. is there a deguassing coil around the tube?

the racing lines look like the flyback is turned up to high but it looks red so maybe its the red driver, not sure on that one. GOD BLESS
 
The line could be you have the tube yoke to far back. Next time measure the yoke and rings distance from the end of the tube. just a thought
 
Thanks for the advice Mrazy1, I really appreciate it.

If I move the monitor around the color and shape of the splotch changes a little.

I tried turning the flyback brightness down some, the race stripes were still there.

Here are a couple more pictures (after I adjusted the convergence). I'm really happy with the picture, if I can just get these little problems ironed out.

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Monitor looks good. Yes, it's a gauss issue. Build your own degaussing wand, or get a high powered electric drill (plug in kind) and run that in front of the screen. Run the drill in front of the screen, and slowly pull it away, drawing circles with it as you pull it away.

If that doesn't work, you should already have most of what you need to build your own degaussing wand though - you can take the degaussing ring from the old TV and use that. From there it's just a quick trip through Google Land to find out how to make your own degaussing wand.
 
Monitor looks good. Yes, it's a gauss issue. Build your own degaussing wand, or get a high powered electric drill (plug in kind) and run that in front of the screen. Run the drill in front of the screen, and slowly pull it away, drawing circles with it as you pull it away.

If that doesn't work, you should already have most of what you need to build your own degaussing wand though - you can take the degaussing ring from the old TV and use that. From there it's just a quick trip through Google Land to find out how to make your own degaussing wand.

Thanks for the info -- I did a bit of Googling, and saw that there are really cheap degaussing wands on ebay (link below). Anybody ever use these?

http://www.ebay.com/itm/Degausser-C...?pt=US_Tablet_Accessories&hash=item2eba328bbb
 
That should work OK, I guess. Why not roll your own? It's more satisfying that way ;)

LOL @ the description: "A must have for every family."
 
That should work OK, I guess. Why not roll your own? It's more satisfying that way ;)

LOL @ the description: "A must have for every family."

Yea it easy. YOu have the old tv with the on/off switch and the old tv deguassing wire and the plug wire to the old tv. just take the wire and fold it into a small circle.

I am building one myself. only I bought the push button (none lock on/off) for it.
 
Just a thought You may have your degaussing wire not close enough to the front of the tube but I dont remember if that wire is live all the time or if it only turns on when power up?? anyone know for sure??
 
It is pretty close to the front of the tube, I tried to reattach it in the same way it was on the monitor.

Just to be clear, I used the gauss wire from the original k4903 monitor, not the TV's.

I was thinking about trying to make one of the wands, but for $7.99 shipped, that is really tempting!
 
I was thinking about trying to make one of the wands, but for $7.99 shipped, that is really tempting!

Something tells me you might as well toss $8 in the toilet.

I've never seen a true CRT degaussing coil that wasn't circular. Punch degaussing coil in Ebay's search box and see what you get.....every single one is circular except those cheap Asian things. I'm not saying it won't work, but at $8 shipped from Asia.....I wouldn't expect much.

These guys have nice 10" ones for $12.95....
http://www.usamusement.com/nos_list.html
They are new....retail at around $40-$60. They got cases in a buy-out. I see these guys all the time. I could grab you one the next time I'm at their warehouse, and you could pick it up next time you swing by my place.

Edward
 
Edward, that sounds fantastic, accept your offer with great enthusiasm! Thanks so much! :-D

I was concerned that the cheap one might be a waste, thanks for all the feedback everyone! You guys are great. I've really just started learning this stuff, it's great to get some feedback and help from the pros!
 
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The one I made is about 6 " made from an old TV.
Vongoosewink You are doing a great job. Just want to answer my own question that the Degauss isnt on all the time only at fire up and yes you did the right thing there by using the one that came with the chassi.. I have many year of experience in electronics but not on games I am learning myself.. I have done a few tube swapps and all mine been really easy. no real problems. but I knew a few thing already but had to find out things on these forums. Everyone has been great. GOD BLESS
 
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