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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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Sylvania TV Problems
Hello all...
Model number RAC128WA03, marked as being made by North American Philips in Knoxville, TN. Says "Sylvania" on the front panel. This is a set I keep on my porch...and when the weather is bad, the set comes indoors because the porch is enclosed but unheated and uncooled. It is a nice little table set in good condition and it has been kept pretty clean over the years. Problems: The picture occasionally becomes sort of a soft but pronounced cyan (blue) in color. The shift isn't so bad that all other colors are forced away, but some colors simply do not appear. When the color control is turned completely off and a black and white picture is displayed, the syptom still appears in a way that seems to shift color temperature. This is something the set only started doing recently and a hard whack on the side may or may not fix it. At the very least it will produce an attempt at switching to the proper colors. I reckon this is bad solder or marginal parts more than anything else. Is there anything specific I should be looking for? The next problem seems perhaps a bit more serious and certainly affects viewability more than the first problem. Periodically the set acts like the screen (G2) control on the flyback is being slowly turned up just until white lines appear softly on the screen. Along with this effect, the picture on the screen will get brigher and brighter. After a second or so of displaying the bright picture with faint white lines, the set reverts to a normal picture and the process happens again. I'd say it is repeated about every 5 seconds. This problem never goes away as long as the set is powered up, but it won't start until the set has been running for --say-- 30 seconds. I have had very good performance from this set, and I like the way it looks and works, so I'd like to repair or get an idea of what is wrong if at all possible. Thanks in advance to anyone who can give any ideas or thoughts! William |
#2
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Sylvania TV Problems
There may be a cold solder joint(s), in the video processing or CRT bias
paths to start with. The changing of the brightness may be the high voltage multiplier. In your set, it is most likely integrated with the flyback transformer, and all are replaced as a module. You can try to rotate the G2 or bias pot back and forth a little in case it is sitting on a sort of intermittent spot, but more than likely the HV multiplier section is bad. -- Greetings, Jerry Greenberg GLG Technologies GLG ============================================== WebPage http://www.zoom-one.com Electronics http://www.zoom-one.com/electron.htm Instruments http://www.zoom-one.com/glgtech.htm ============================================== "William R. Walsh" m wrote in message news:YFb8b.420878$Ho3.67141@sccrnsc03... Hello all... Model number RAC128WA03, marked as being made by North American Philips in Knoxville, TN. Says "Sylvania" on the front panel. This is a set I keep on my porch...and when the weather is bad, the set comes indoors because the porch is enclosed but unheated and uncooled. It is a nice little table set in good condition and it has been kept pretty clean over the years. Problems: The picture occasionally becomes sort of a soft but pronounced cyan (blue) in color. The shift isn't so bad that all other colors are forced away, but some colors simply do not appear. When the color control is turned completely off and a black and white picture is displayed, the syptom still appears in a way that seems to shift color temperature. This is something the set only started doing recently and a hard whack on the side may or may not fix it. At the very least it will produce an attempt at switching to the proper colors. I reckon this is bad solder or marginal parts more than anything else. Is there anything specific I should be looking for? The next problem seems perhaps a bit more serious and certainly affects viewability more than the first problem. Periodically the set acts like the screen (G2) control on the flyback is being slowly turned up just until white lines appear softly on the screen. Along with this effect, the picture on the screen will get brigher and brighter. After a second or so of displaying the bright picture with faint white lines, the set reverts to a normal picture and the process happens again. I'd say it is repeated about every 5 seconds. This problem never goes away as long as the set is powered up, but it won't start until the set has been running for --say-- 30 seconds. I have had very good performance from this set, and I like the way it looks and works, so I'd like to repair or get an idea of what is wrong if at all possible. Thanks in advance to anyone who can give any ideas or thoughts! William |
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