At 19:31 07/10/2001, you wrote:
> > >Aluminium won't do a darn thing about 50Hz magnetic fields. You want
> > >something like mild steel, or better still mu-metal (if you can get it at
> > >a sensible price, or indeed, at all).
> >
> > Okay, that makes sense. I *should* be able to get hold of some of this
> > "mu-metal" stuff - I know people at an electicity/electronics R&D
> lab.... :)
>
>It's worth asking. Really you need to anneal it after bending it to
>shape (bending it will affect the magnetic properties and will make it
>less good as a sheild). But in practice if you don't bend it except at
>the corners where you have to, it will be a lot better than nothing.
Anneal - is that where you heat it up & hit it with a hammer? Or do you
just heat it up and let it cool again? I forget now... It's been a long
long time since I had any metalwork lessons.
> >
> > I will have a poke around with my multimeter tomorrow...
>
>In another post you mentioned you could easily detect the stray field
>with a screwdriver (ouch!).
Well, a screwdriver bit. It's one of those 1.5in long bits which go into a
handle, or drill.
>OK, take the loads off the transformer. Pull the power connector off the
>mainboard, and unplug the cable to the monitor. Is there still the same
>stray field (if so, suspect shorted turns or similar in the transformer).
Yes, it's still there, albeit not quite so strongly. Still enough to induce
a noticable vibration in my magnet-on-a-stick.
>If not, then reconnect one of the loads (say the mainboard) and see what
>the field is like now. Then try connecting the other load (monitor) on
>its own and see what the field is like.
>
>If one of the loads causes a rediculous increase in the field, then check
>the rectifiers and smoothing capacitors in that section...
No, not ridiculous (at least, I don't think so), but there is a noticable
increase when the monitor load is added.
From this, can I deduce that:
a) The transformer is kaput (or, at least, on its way out)
b) There may be a borderline problem inside the monitor cabinet.
I've not got around to the multimeter test yet - I need to take the
mainboard out to access the underside, and that's not a task to be doing at
2:20am....
--
Cheers, Ade.
Be where it's at, B-Racing!
http://b-racing.co.uk
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Received on Sun Oct 07 2001 - 20:19:22 BST