"d6xkr" u45258@uwe wrote in message news:882f878cb28b5@uwe...
hi


my monitor has pin cushion effect problem, and the picture edges are out
of
the view. the monitor controls don't solve it as the (horizontal size)/
(pincushion\trapezoid) controls don't have effect anymore. this problem is
the same as this one posted here
http://www.electronicskb.com/Uwe/For...uashed-picture

but no body offers a solution. i already opened the monitor case, i found
four chips;

1. LSC506429P 2. TDA4858 3. ATMEL008 4.
KA3842B
JD157V2 67974 24C08
E009C
IJ35BCTBW0025 YTD0021

only two of these i could know what they do, no. 2 and 3.

the first one is motorola and is discontinued, i couldn't find it's
datasheet
so to decide whether was it a culprit or not, i couldn't bring the
datasheet
of the fourth chip either.

the image is normal except for this problem, and all the controls work
fine
except for those i mentioned.

the caps seem to have leaked, but i'm not sure as the monitor was never
opened until the problem showed up which was last thursday. these caps
look
as if they have black heavy dust stuck to thier metal top, and there is
plenty of it everywhere inside but only very few caps have it like this
and
they happen to be arround the four ics i mentioned. but also that
indicates
the leak is old, and the problem appeared three days earlier which adds to
the confusion. anyway the first thing to do morning is to get new
replacements, but i need also to know if someone else had this problem and
if
it was/or not related to the capacitors? did he manage to solve it or not
and
how?

thanx


Seems to me that the advice being given on that forum, whilst not
definitive, is never-the-less exactly right. I would suggest that the first
thing to do would be to check the pincushion amp, and its drive. Also, if
any caps *have* leaked (and you are not confusing the glue that's often
found around their bases, with leaked electrolyte), then they need to be
replaced. Just because they had enough go in them to just about do their job
three days ago, doesn't mean that one of them hasn't gasped its last today.

To use a car analogy, you can drive around today with half a millimetre of
lining material on your brake pads, that stop the car today, and squeal
metal on metal tomorrow ...

The 24C08 is an EEPROM, where all of the setup parameters are stored. It's
not at all unusual for these to get corrupted in TV sets, and to produce
symptoms like you describe, which are not correctable. However, it's often
necessary to pre-program a new blank one with a basic set of parameters,
before it will work.

Finally, a warning. If you are not used to working on monitors, take extreme
care, as they employ switchmode power supplies, which are (literally)
potentially lethal. Also the high voltage generation circuits for the CRT
can give you a nasty bite, as can the CRT itself, long after you have
switched off.

Arfa