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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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Zenith TV 1994 model SM2568S picture compressed
Hi fellow techs,
This 1994 25" Zenith TV model SM2568S has a complete picture which occupies about 40% of the CRT face plate.The picture is compressed and centered about the middle of the screen.(Wide black bar on top and wide black bar on the bottom) My coworker has a 1995 27" Zenith TV with the exact same problem. Sometimes I get the full picture with 2 fine horizontal lines in the middle. All the caps around the vertical IC are OK.(ESR OK)The vertical IC LA7838 has been resoldered.Is there something else I need to check before I grab the scope? Best regards, Jacques |
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#2
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Jacques Carrier wrote:
Hi fellow techs, This 1994 25" Zenith TV model SM2568S has a complete picture which occupies about 40% of the CRT face plate.The picture is compressed and centered about the middle of the screen.(Wide black bar on top and wide black bar on the bottom) My coworker has a 1995 27" Zenith TV with the exact same problem. Sometimes I get the full picture with 2 fine horizontal lines in the middle. All the caps around the vertical IC are OK.(ESR OK)The vertical IC LA7838 has been resoldered.Is there something else I need to check before I grab the scope? Best regards, Jacques I believe I have the same set, and once encountered the same problem. Unfortunately I too changed the vertical IC before I discovered a poor solder joint on one of the caps for that chip. Look REAL close at your PWB to see if you don't have the same problem. |
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#3
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Ken wrote in message ...
Jacques Carrier wrote: Hi fellow techs, This 1994 25" Zenith TV model SM2568S has a complete picture which occupies about 40% of the CRT face plate.The picture is compressed and centered about the middle of the screen.(Wide black bar on top and wide black bar on the bottom) My coworker has a 1995 27" Zenith TV with the exact same problem. Sometimes I get the full picture with 2 fine horizontal lines in the middle. All the caps around the vertical IC are OK.(ESR OK)The vertical IC LA7838 has been resoldered.Is there something else I need to check before I grab the scope? Best regards, Thanks a lot for the tip Ken. I resoldered all components around the vert. IC and the set is working fine! Jacques Jacques I believe I have the same set, and once encountered the same problem. Unfortunately I too changed the vertical IC before I discovered a poor solder joint on one of the caps for that chip. Look REAL close at your PWB to see if you don't have the same problem. |
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