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  #16  
Old 05-29-2007, 12:10 PM
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compucat compucat is offline
1949 Motorola 9VT1
 
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This set does have automatic degaussing. If I display a red raster and rotate the set, I can watch the purity change. I read elsewhere in this forum that round tubes are more sensitive to magnetic fields. Is this true? This is my first color roundie. I always thought convergence was a one-time setup procedure but someone posted that every time a roundie is moved to a new location, purity and convergence may need to be redone. Is this just a characteristic of early color tv? If it is, I don't have a problem with it. I'll redo the setup in its final location and I expect everything will be fine with it. As long as I don't move it, the picture stays great.
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  #17  
Old 05-29-2007, 12:18 PM
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If these sets have to be setup whenever they are moved, I expect most people did not have them adjusted whenever they moved the set to another room or another house, etc. After the initial setup by the service technician, these sets probably never looked their best again. No wonder some people remember these as having a lousy picture.
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  #18  
Old 05-29-2007, 12:45 PM
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  #19  
Old 05-29-2007, 01:51 PM
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Quote:
Originally Posted by compucat
If these sets have to be setup whenever they are moved, I expect most people did not have them adjusted whenever they moved the set to another room or another house, etc. After the initial setup by the service technician, these sets probably never looked their best again. No wonder some people remember these as having a lousy picture.
Exactly. They are extremely sensitive to magnetic fields, including the one of the earth. If a roundie is going to look it's best, it should be degaussed and set up in the position it is going to sit.

Automatic degaussing is a good first step toward a "permanent setup", but II would bet the convergence will also change slightly if the orientation of the set to the magnetic field of the earth changes, even on a set with automatic degauss. I haven't tried anything like that lately. If you're curious, try it and see.

In any event, the the static convergence and purity magnets are pretty loose on most roundies. The adjustments probably move themselves if you haul the set. They always did when I moved my RCA.

Anothr reason they looked bad "back in the day" is that people either wouldn't or didn't adjust the front panel controls right. In general, you had to re-adjust if you changed channels, and sometimes even when the program changed. Most people turned the brightness up until it was blooming, and the chroma up until everybody's face was pumpkin orange, and left it that way. I had no idea roundies could produce an outstanding picture until I got my first one.

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  #20  
Old 05-29-2007, 02:15 PM
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To get a really good picture on mine I had to go through the Sams and follow all the setup procedures, not just for convergence but for brightness range, CRT bias, AGC and so forth. It took quite a bit of tweaking but now I have good range on all the controls. The brightness will bloom a little and go out of focus if turned up too high but I have noticed this on all tube TVs. I have the front panel controls on very conservative settings and overall performance is excellent. I am especially careful not to have the brightness and contrast up too high as it is harder on the tube. I want this set to last a long time.
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  #21  
Old 05-29-2007, 10:06 PM
3Guncolor 3Guncolor is offline
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One thing I learned from the guys that worked on these sets in the day, at the shop they always set them up with the set facing north and south. They told me it was the only way to correctly adjust the CRT. I still do it this way today on our current monitors it does seem to help.
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  #22  
Old 05-30-2007, 06:48 AM
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Quote:
Originally Posted by 3Guncolor
One thing I learned from the guys that worked on these sets in the day, at the shop they always set them up with the set facing north and south. They told me it was the only way to correctly adjust the CRT. I still do it this way today on our current monitors it does seem to help.
If you set it up with a North/South orientation will it adversely affect the picture if the install orientation is East/West? I went through the setup again last night in the set's final location in which the screen faces Northwest. The setup went well but I still have a little bit of impurity in one area of the screen. It is not too bad and I may just live with it since the convergence is really good now. It is not that noticeable during a color program. These sets really are sensitive with regard to their setup. I have noticed that the fleshtones on this set are great, very natural. This set has that warm color that I have always loved in Zeniths.
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  #23  
Old 05-30-2007, 11:11 AM
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I have a 25MC30 (same basic set, mine in a cheap metal cabinet) and I could not get perfect purity in a couple spots no matter what. The trick that worked was stacking "refrigerator" magnets along the inside of the cabinet near the face of the crt. I ended up with about 6 stacked near the speaker and about 4 on the other side. A good place to get them is in the bottom of an old shower curtain, which has them sewn in so it will stick to a cast iron tub. Anyway, for me it worked. Later when I moved the set I was able to do away with some of the magnets.
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Old 05-30-2007, 04:20 PM
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  #25  
Old 05-31-2007, 07:35 AM
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I changed the video output tube last night which seemed to eliminate the flashing in the picture. I touched up the AGC, buzz control and greyscale drive adjustments. The set is really looking good. I think I am at the point where I need to bolt the chassis down, install the back and bottom covers and declare victory. If I don't, I'll never stop messing with this thing. I get like this when I finish TV restorations. I keep checking and rechecking to make sure everything is right. After a while though, I relax and enjoy the results. I put on a DVD of classic commercials and it was like time travel watching 1960s and '70s commercials on a mid-Sixties TV.
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