Monitor deflection magnets; what to do when one falls out & breaks?

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Thu Jul 15 18:15:34 2004

>
>
> Hi,
>
> I have an old B&W "specialty" monitor which recently stopped working.
> In the process of moving it around (to/from repair place) I noticed a
> little black "tube magnet" dropping out when I took the cover off.
>
> At the time I didn't think much of it (those in the know can chuckle now).

There are few, if any, unimportant components in monitors :-)

>
> So, after a bout of replacing bad caps with no luck, I eventually broke
> down and replaced the deflection board and the monitor sprang to life.
>
> Much joy.
>
> (note: "specialty" = designed for a specific computer with a special ECL

What machine?

> video connection and has no standard connector or interface. and no
> schematics)

No schematics is not an excuse for not repairing things properly. I've
had to start with no schematics quite often (and by the end of the repair
I normally have my own set of scheamtics...)

>
> So, monitor is working. I proceed to adjust the H & V size, linearity, etc...
>
> I notice that the bottom and sides will square up nicely but the top
> edge has a large "dip" in the middle. No amount of trimmer fiddling will
> fix this.
>
> light goes off. "found" tube magnet is part of yoke assembly.

Quite probably...

>
> So, I notice where the missing magnet came from. Naturally it's on the
> top side of the yoke assembly.
>
> But - the "tube" has broken into 3 pieces (it was broke when I found it.
> honest). I carefully glued it back together (no glue in the joints,

What glue did you use? Isocyano acryliic hydro-copolymerising adhesive is
probably the bsst for this becuase it's such a thin layer. Did you
carefully align the broken parts (so no gaps) when you stuck them together?

> however) and replaced it. This helped a little but did not cure the
> problem.
>
> [note to reader: I never took that fields course. I know nothing of magnets.]
>
> So,
>
> - is a broken magnet pushed back together not as good as a whole magnet?
> (strength wise)

Should be, provided there are no gaps.

>
> - can I get a new magnet somewhere?

Is this a monochrome monitor? If so, try expserimenting with other small
magnets. I don't think you can do much permanent harm.

-tony
Received on Thu Jul 15 2004 - 18:15:34 BST