DIYbanter - View Single Post - Sharp 25K-S100 Convergence Issue

wrote in :

On 27-Dec-2004, Tony wrote:

Hi, I have a Sharp 25K-S100 and the color convergence at the
corners is not good at all. The upper-left corner is especially
bad and after leaving the TV on for more than about 10 minutes, a
small purple color patch develops in that area. Any idea how I can
repair this? I know in the FAQ it mentions adjusting the ring
magnets and the yolk, but I'm not 100% sure how I would begin doing
this, if this will even work, and can I perform this with the
television on to see if everything will work ok? Please help me,
thanks.

It halps if you have a manual or specific information on
converging Sharp sets. You have to converge with the set on
else you can't see what's happening. Most ring magnets are
stuck together with paint and it's a pain in the butt to separate
them without breaking them. It's quite easy to electrocute yourself
whilst watching the picture in a mirror, and not watching where
your hands are going. I use teletext to see convergence as it's
impossible to converge on a normal picture. Mark the position
of the rings before you start so you can get back to where they were.
Make sure the degauss circuit is working before you start, it
may be the only thing that is wrong. It may not be possible to
converge the set if it has had the flyback replaced with a
generic. Some sets need stick on magnets to sort out
problems at the screen corners. Removing metal screens,
if there are any, can upset convergence, so the history of
repairs may provide a clue as to why the convergence is off.
To do the job properly you need a convergence pattern
generator, a DVD player on pause, with text such as
the distribution rights on the screen, or teletext is a poor
substitute. If a generic flyback has been used the EHT may
be out of spec, and if the scan amplitudes have been adjusted
to compensate for the different sensitivity due to the
changed EHT, you've got problems, which is why the sets
history is useful, like when did the problem appear, just after
a repair?

It's actually been a minor problem for a while, the TV has never been in
for repairs and at the cost it'd probably be to have them do it, it'd be
more economical to buy a brand new set. But since this is going to be
for my dorm room, it was basically my grandparents' old TV set. At this
point should I just open it up and look for anything in particular that
could be wrong, maybe one of the ring magnets is out of place or
something along those lines? Or even this yolk that people talk about?
And what's the danger area to touch, the copper coil things only or is
there more? Thanks for all your help!