"Andy" wrote in message
...
I am in the UK.

I have been cleaning out the dust from the inside of my monitor and I
just moved a few pots to make sure their tracks are clean and returned
the pots to how they were.


With respect, that was an extremely foolish thing to do. If you don't
understand the inside of mains operated equipment, you shouldn't be inside
it, let alone turning adjustments. If the pots had been dirty but producing
no symptoms, turning them could have caused a fault that wasn't there before
by dragging the dirt under the wiper.


In fact the only pots I can find are three right next to the coil on the
neck of the picture tube and they are marked:

Y-HC: Y and in small letters, HC
Delta V: capital delta symbol then V
YV: Y and in a small letter, V

What do these do?


They are convergence pots. They alter the relationship of the geometries
between the beams. The red, green and blue images which make up the colour
picture on your monitor must overlap as close to perfectly as possible,
otherwise you will see red, green or blue fringes on different parts of the
image. They should only ever be altered by someone who understands how to
set them up- they can be very difficult to get back if you don't know what
you're doing.

If the picture looks OK, you've got away with it.

At least you didn't alter the static convergence rings on the CRT neck- that
really would have caused problems.

Dave