Video distortion on TV tube

[Dave]

Okay, I've fixed the vertical hold problem mentioned in another string of
posts, and now the bottom of the picture is overlaid or superimposed over
the top of the picture, at the top of the screen,. I was thinking this is
most likely an adjustment, but couldn't find the pot that affected it and
ended up pulling the CRT out to gain access to and adjust a variable
inductor at the back middle of the PC board. So now the problem is not as
bad, but it's still there. I'm guessing this is some sort of wrap-around,
but have no idea as to what to do about it. Any suggestions? Surely this
isn't the first time something like this as happened with a TV. There are
four pots on this board, but one of them doesn't seem to do anything to the
picture, so I am trying to leave it where it was. If anyone has any ideas,
I'm all ears.

Thanks bunches.

Dave

 

[hrhofmann@att.net]

On Jun 1, 10:54 am, "Dave" <db5...@hotmail.com> wrote:

Okay, I've fixed the vertical hold problem mentioned in another string of
posts, and now the bottom of the picture is overlaid or superimposed over
the top of the picture, at the top of the screen,.  I was thinking this is
most likely an adjustment, but couldn't find the pot that affected it and
ended up pulling the CRT out to gain access to and adjust a variable
inductor at the back middle of the PC board.  So now the problem is not as
bad, but it's still there.  I'm guessing this is some sort of wrap-around,
but have no idea as to what to do about it.  Any suggestions? Surely this
isn't the first time something like this as happened with a TV.  There are
four pots on this board, but one of them doesn't seem to do anything to the
picture, so I am trying to leave it where it was.  If anyone has any ideas,
I'm all ears.

Thanks bunches.

Dave

How about a make model, year age info, etc?????

 

[spamtrap1888]

On Jun 1, 8:54 am, "Dave" <db5...@hotmail.com> wrote:

Okay, I've fixed the vertical hold problem mentioned in another string of
posts, and now the bottom of the picture is overlaid or superimposed over
the top of the picture, at the top of the screen,.  I was thinking this is
most likely an adjustment, but couldn't find the pot that affected it and
ended up pulling the CRT out to gain access to and adjust a variable
inductor at the back middle of the PC board.  So now the problem is not as
bad, but it's still there.

Sounds like your original problem was height or linearity, not
vertical hold.

http://books.google.com/books?id=XOMDAAAAMBAJ&pg=PA170&lpg=PA170&source=bl&ots=SMB4elO4c3&sig=JTviy4TLebvoDdYd5Ky9ObZsrzs&hl=en&ei=owznTYvhI4nRiALXofnNCQ&sa=X&oi=book_result&ct=result&resnum=2&ved=0CCQQ6AEwATgK#v=onepage&q&f=false

 

On Jun 1, 8:54 am, "Dave" <db5...@hotmail.com> wrote:

Okay, I've fixed the vertical hold problem mentioned in another string of
posts, and now the bottom of the picture is overlaid or superimposed over
the top of the picture, at the top of the screen,.  I was thinking this is
most likely an adjustment, but couldn't find the pot that affected it and
ended up pulling the CRT out to gain access to and adjust a variable
inductor at the back middle of the PC board.  So now the problem is not as
bad, but it's still there.  I'm guessing this is some sort of wrap-around,
but have no idea as to what to do about it.  Any suggestions? Surely this
isn't the first time something like this as happened with a TV.  There are
four pots on this board, but one of them doesn't seem to do anything to the
picture, so I am trying to leave it where it was.  If anyone has any ideas,
I'm all ears.

Thanks bunches.

Dave

Replace the bad electrolytics in the vertical output particularly if
it's inside the feedback look. Sony 8" color monitors are notorious
for this. Don't screw with the pots but I'm sure you already did. If
you ever need to move things more than 10% it's broken or somebody did
what you're doing now. Diddling but it won't take long to correct once
the bad caps are gone. And don't buy cheap crap. Look for highest
ripple current.

G˛

 

[Mark Zacharias]

<hrhofmann@att.net> wrote in message
news:96815a4d-1573-4daf-9423-d451d3828357@n11g2000yqf.googlegroups.com...
On Jun 1, 10:54 am, "Dave" <db5...@hotmail.com> wrote:

Okay, I've fixed the vertical hold problem mentioned in another string of
posts, and now the bottom of the picture is overlaid or superimposed over
the top of the picture, at the top of the screen,. I was thinking this is
most likely an adjustment, but couldn't find the pot that affected it and
ended up pulling the CRT out to gain access to and adjust a variable
inductor at the back middle of the PC board. So now the problem is not as
bad, but it's still there. I'm guessing this is some sort of wrap-around,
but have no idea as to what to do about it. Any suggestions? Surely this
isn't the first time something like this as happened with a TV. There are
four pots on this board, but one of them doesn't seem to do anything to
the
picture, so I am trying to leave it where it was. If anyone has any ideas,
I'm all ears.

Thanks bunches.

Dave

How about a make model, year age info, etc?????

It's foldover. Common problem. Replace the boost capacitor, and maybe the B+
cap for the vertical output.

Mark Z.