| Science Forum Index » Electronics - Repair Forum » sylvania model srt2027 vertical foldover... |
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| tronic... |
 Posted: Wed Nov 04, 2009 2:48 pm |
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Guest
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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? |
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| Mark Zacharias... |
| Posted: Wed Nov 04, 2009 10:05 pm |
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"tronic" <swmorison at (no spam) comcast.net> wrote in message
news:ba311467-308c-4441-818b-694d4b0afc11 at (no spam) a21g2000yqc.googlegroups.com...
[quote]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?
[/quote]
Foldover isn't the IC - there's one or more caps you missed.
Mark Z. |
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| tronic... |
| Posted: Thu Nov 05, 2009 12:42 pm |
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On Nov 4, 10:05 pm, "Mark Zacharias" <mark_zachar... at (no spam) sbclobal.net>
wrote:
[quote]"tronic" <swmori... at (no spam) comcast.net> wrote in message
news:ba311467-308c-4441-818b-694d4b0afc11 at (no spam) a21g2000yqc.googlegroups.com...
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.
[/quote]
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 |
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| Mark Zacharias... |
| Posted: Fri Nov 06, 2009 7:30 am |
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Guest
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"tronic" <swmorison at (no spam) comcast.net> wrote in message
news:aadbe3f6-0b49-49c1-9395-3fc3b3aed403 at (no spam) p33g2000vbn.googlegroups.com...
On Nov 4, 10:05 pm, "Mark Zacharias" <mark_zachar... at (no spam) sbclobal.net>
wrote:
[quote]"tronic" <swmori... at (no spam) comcast.net> wrote in message
news:ba311467-308c-4441-818b-694d4b0afc11 at (no spam) a21g2000yqc.googlegroups.com...
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
[/quote]
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. |
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| tronic... |
| Posted: Sat Nov 07, 2009 6:14 am |
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Guest
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On Nov 6, 7:30 am, "Mark Zacharias" <mark_zachar... at (no spam) sbclobal.net>
wrote:
[quote]"tronic" <swmori... at (no spam) comcast.net> wrote in message
news:aadbe3f6-0b49-49c1-9395-3fc3b3aed403 at (no spam) p33g2000vbn.googlegroups.com...
On Nov 4, 10:05 pm, "Mark Zacharias" <mark_zachar... at (no spam) sbclobal.net
wrote:
"tronic" <swmori... at (no spam) comcast.net> wrote in message
news:ba311467-308c-4441-818b-694d4b0afc11 at (no spam) a21g2000yqc.googlegroups.com....
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 -
[/quote]
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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