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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Red/Green/Blue mis-alignment on Phillips/Magnavox 25In TV
The colors seem to have come out of alignment on my tv. For example, if I have closed-captioning running, I can see a "ghose" of red above and blue below that white lettering. Possibly related, for a few weeks before the the "focus" went away, the tv was "humming" (sounded like 60HZ noise to me). I'd just as soon try to fix this myself if someone can give me some pointers. I'm handy with digital stuff, but haven't done any TV repair before. Thanks - jim |
#2
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You need to apply the proper signal generator and do a full yoke
purity, convergence, and geometry adjustment. |
#3
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Ok.. thanks... but... a followup question.. why would the focus have
gone bad to begin with? wrote: You need to apply the proper signal generator and do a full yoke purity, convergence, and geometry adjustment. |
#4
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#5
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The yoke is bad like Ol Duffer said. Pretty common failure.
Ol' Duffer wrote: In article , says... The colors seem to have come out of alignment on my tv. For example, if I have closed-captioning running, I can see a "ghose" of red above and blue below that white lettering. The term for this is convergence. Or in your case, misconvergence. Possibly related, for a few weeks before the the "focus" went away, the tv was "humming" (sounded like 60HZ noise to me). This may have been the yoke rattling at the vertical scan rate. The yoke is a molded and glued mess of ferrite, sheet metal, and plastic wound with specially shaped coils of wire that fits over the neck of the CRT, and has the job of deflecting the electron beams to generate the sweep (raster). Part of the factory convergence procedure involves warping the yoke to move the center of its magnetic fields into the best position for the colors to line up. They jam rubber wedges or strips of cardboard under it to hold its shape. With age, the plastic can sag or crack, glue gets brittle, and sometimes things get loose internally. There is a good chance you would have to replace the yoke to get it right, and they are pricey. The alignment procedure is best done with a pattern generator, and can be tricky. I'd just as soon try to fix this myself if someone can give me some pointers. I'm handy with digital stuff, but haven't done any TV repair before. If you are lucky, one of the rubber wedges may have fallen out from dried-up glue, and you can jam it back in place and improve convergence. The fates are not usually so kind. You can also fiddle with the rings on the CRT neck, and maybe improve it a bit. Make note of their original position so you can start over if you make things worse. This is about all the average do-it- yourselfer can do. |
#6
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Ol' Duffer wrote: In article , says... Part of the factory convergence procedure involves warping the yoke to move the center of its magnetic fields into the best position for the colors to line up. They jam rubber wedges or strips of cardboard under it to hold its shape. With age, the plastic can sag or crack, glue gets brittle, and sometimes things get loose internally. THIS is how they build TELEVISIONS!?! Yikes!!! No wonder they go out of tune so fast and so unpredictably. No wonder I have to re-focus a brand new Sony that just came in the house! "Jam rubber wedges"??? I thought that's how they loosened up or tightened up the handling of NASCAR race cars!!! "Get loose internally...with age"? It'll get loose just moving it across the room to where it will be watched! LOL Thanks for bringing this up - that's scary! -CC |
#7
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#8
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"ChrisCoaster" wrote in message oups.com... THIS is how they build TELEVISIONS!?! Yikes!!! No wonder they go out of tune so fast and so unpredictably. No wonder I have to re-focus a brand new Sony that just came in the house! "Jam rubber wedges"??? I thought that's how they loosened up or tightened up the handling of NASCAR race cars!!! If you don't like that you'll hate seeing how they align the doors on your new car! N |
#9
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ChrisCoaster wrote:
THIS is how they build TELEVISIONS!?! Yikes!!! No wonder they go out of tune so fast and so unpredictably. No wonder I have to re-focus a brand new Sony that just came in the house! "Jam rubber wedges"??? I thought that's how they loosened up or tightened up the handling of NASCAR race cars!!! You obviously have no idea what you're talking about. This method has been in use for 30 years so if it was such a bad idea some other method would have been developed. After the wedges are placed they are glued in place "Get loose internally...with age"? It'll get loose just moving it across the room to where it will be watched! LOL Not unless you consider having an 800 pound gorilla throw it across the room "Moving a TV" Thanks for bringing this up - that's scary! -CC Scary is people who don't know what their doing trying to tell people how to do their jobs. Do you stand over the shoulder of the bomb squad and tell them to let you kick the bomb to see if it will go off? -- Beware of those who post from srvinet.com! Michael A. Terrell Central Florida |
#10
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Well, both my direct-views are under a year old, so I guess I'd better
start looking into that converter if that's the case. Of course a set will last 5 years with the Contrast left in the jacked-up factory position! -CC (who will get at least 10 years out of his CRTs) |
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