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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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Help Please: Sudden Video Failure with Sony SLV 770HF VCR
I have owned a Sony SLV 770HF VCR for several years, but have used it only
infrequently. When I have used it, it has alaways worked well. Now, with no prior warning, the machine appears to have failed. Upon turning it on everything seems normal. When playing back a tape, the first few minutes also seem normal, but then scattered horizontal interference begins to intrude as if the tape was not making good contact with the head. The interference is followed at an interval that varies from 5 to 15 minutes by loss of the chroma signal. The gray scale in the resulting monochrome image then slowly compresses until only white outlines on a black background are visible. Within 5-10 additional minutes, the high contrats image disappears entirely and cannot be recovered. If the machine is turned off for at least 30 minutes, the entire sequence repeats. The symptoms suggest a time/temperature dependent failure, but I am puzzled by why a temporary recovery is possible when the machine is turned off. If anyone has repair experience with a Sony VCR with a similar progression: flutter, lack of chroma, lack of gray scale, lack of image, I would be very grateful for your advice. I would like to keep the machine and should be able to repair it myself, but I need some help in diagnosing the source of the problem. Thanks very much. Sincerely, Ron |
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Help Please: Sudden Video Failure with Sony SLV 770HF VCR
"Ron Kalil" wrote in message ... I have owned a Sony SLV 770HF VCR for several years, but have used it only infrequently. When I have used it, it has alaways worked well. Now, with no prior warning, the machine appears to have failed. Upon turning it on everything seems normal. When playing back a tape, the first few minutes also seem normal, but then scattered horizontal interference begins to intrude as if the tape was not making good contact with the head. The interference is followed at an interval that varies from 5 to 15 minutes by loss of the chroma signal. The gray scale in the resulting monochrome image then slowly compresses until only white outlines on a black background are visible. Within 5-10 additional minutes, the high contrats image disappears entirely and cannot be recovered. If the machine is turned off for at least 30 minutes, the entire sequence repeats. The symptoms suggest a time/temperature dependent failure, but I am puzzled by why a temporary recovery is possible when the machine is turned off. If anyone has repair experience with a Sony VCR with a similar progression: flutter, lack of chroma, lack of gray scale, lack of image, I would be very grateful for your advice. I would like to keep the machine and should be able to repair it myself, but I need some help in diagnosing the source of the problem. Thanks very much. Sincerely, Ron Check head preamp board: Ic1 for a leaky 2.2uf/35 Smd Cap. Also, look for bad solder joints on the board, a common problem. |
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