"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.