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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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sylvania model srt2027 vertical foldover
I need a schematic or good advice. I tried replacing some of the caps.
c541 a 100uf and c578 a 47uf . i dont know what part of the curcuit these belong too, but they didnt look bad and they didnt fix the problem.I tried to use a heat gun on the curcuit. i guess the next step is to replace ic 551 the la78045. has anyone seen this before so i am not buying unneeded parts? |
#2
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sylvania model srt2027 vertical foldover
"tronic" wrote in message
... I need a schematic or good advice. I tried replacing some of the caps. c541 a 100uf and c578 a 47uf . i dont know what part of the curcuit these belong too, but they didnt look bad and they didnt fix the problem.I tried to use a heat gun on the curcuit. i guess the next step is to replace ic 551 the la78045. has anyone seen this before so i am not buying unneeded parts? Foldover isn't the IC - there's one or more caps you missed. Mark Z. |
#3
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sylvania model srt2027 vertical foldover
On Nov 4, 10:05*pm, "Mark Zacharias"
wrote: "tronic" wrote in message ... I need a schematic or good advice. I tried replacing some of the caps. c541 a 100uf and c578 a 47uf . i dont know what part of the curcuit these belong too, but they didnt look bad and they didnt fix the problem.I tried to use a heat gun on the curcuit. *i guess the next step is to replace ic 551 the la78045. has anyone seen this before so i am not buying unneeded parts? Foldover isn't the IC - there's one or more caps you missed. Mark Z. mark Z i replaced all caps in the 500 series curcuit what i see on the top of the screen is "retrace lines" maybe about 2or 3 inches but the picture is ok so i think foldover might be the wrong term |
#4
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sylvania model srt2027 vertical foldover
"tronic" wrote in message
... On Nov 4, 10:05 pm, "Mark Zacharias" wrote: "tronic" wrote in message ... I need a schematic or good advice. I tried replacing some of the caps. c541 a 100uf and c578 a 47uf . i dont know what part of the curcuit these belong too, but they didnt look bad and they didnt fix the problem.I tried to use a heat gun on the curcuit. i guess the next step is to replace ic 551 the la78045. has anyone seen this before so i am not buying unneeded parts? Foldover isn't the IC - there's one or more caps you missed. Mark Z. mark Z i replaced all caps in the 500 series curcuit what i see on the top of the screen is "retrace lines" maybe about 2or 3 inches but the picture is ok so i think foldover might be the wrong term What you are describing is caused by the "boost capacitor" usually 100uF at 35 volts and located physically near the vertical output IC. You can go to bdent.com, register if necessary and get a PDF of your vertical IC. Using that, you can tell which pin the boost cap is associated with. This is important - when the boost cap is bad the vertical IC will usually run HOT and may fail soon if the situation is not corrected. Mark Z. |
#5
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sylvania model srt2027 vertical foldover
On Nov 6, 7:30*am, "Mark Zacharias"
wrote: "tronic" wrote in message ... On Nov 4, 10:05 pm, "Mark Zacharias" wrote: "tronic" wrote in message .... I need a schematic or good advice. I tried replacing some of the caps. c541 a 100uf and c578 a 47uf . i dont know what part of the curcuit these belong too, but they didnt look bad and they didnt fix the problem.I tried to use a heat gun on the curcuit. i guess the next step is to replace ic 551 the la78045. has anyone seen this before so i am not buying unneeded parts? Foldover isn't the IC - there's one or more caps you missed. Mark Z. mark Z i replaced all caps in the 500 series curcuit what i see on the top of the screen is "retrace lines" maybe about 2or 3 inches but the picture is ok so i think foldover might be the wrong term What you are describing is caused by the "boost capacitor" usually 100uF at 35 volts and located physically near the vertical output IC. You can go to bdent.com, register if necessary and get a PDF of your vertical IC. Using that, you can tell which pin the boost cap is associated with. This is important - when the boost cap is bad the vertical IC will usually run HOT and may fail soon if the situation is not corrected. Mark Z.- Hide quoted text - - Show quoted text - thanks i replaced the "boost cap" origanal was a 47uf but it didnt fix it so i tried a 100uf and wualla it fixed it. the bdent.com couldnt display the data sheet but i found it on http://www.audiolabga.com/pdf/LA78045.pdf thank for your help Sam M |
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