scopes [was: how to troubleshoot? ...]

[Dave Halliday]

It could also be a classroom demonstration scope - big enough screen so
everyone could see.

As for fixing them, the larger the screen, the higher the voltage so be very
very careful.

Also, some internal power supplies can hold these voltages for several hours
- maybe not enough to be lethal but certainly enough for you to get a good
shock.




-----Original Message-----
From: Happy Harry [mailto:paia2720 at hotmail.com]
Sent: Monday, January 15, 2001 10:15 AM
To: kasper at industree.org; synth-diy at node12b53.a2000.nl
Subject: Re: scopes [was: how to troubleshoot? ...]


The XYZ unit sounds like a vectorscope. I'm not sure what the
professional use of these are, I think some kind of video
or communication use...

19" is HUGE for a scope.  Maybe its some kind of TV monitor or
test gear ???

Most scopes have the CRT shielded in a mu-metal can, and do
NOT have deflection coils (yoke) like a TV monitor. They use
electrostatic deflection. If you see a yoke like a TV... its not
a scope..

Working on scopes is semi-hazardous. There ARE high voltages involved
but they are similar to TVs in hazard.  A line isolation transformer
is a real good idea... and a schematic if you can get one. If you
are not sure where it is safe to put a probe ground clip... then stay
out for safety.

It is even possible to work on a bad channel of a scope using itself!
But I prefer a working scope to fix a non-working one.
Get the model numbers and inquire... maybe someone has the same or
similar and can hook you up with a schematic.

H^) harry


>From: Kasper Souren <kasper at industree.org>
>To: synth-diy at node12b53.a2000.nl
>Subject: Re: scopes [was: how to troubleshoot? ...]
>Date: Mon, 15 Jan 2001 16:52:14 +0100
>
>On Mon, Jan 15, 2001 at 06:10:53AM +0000, Scott Gravenhorst wrote:
> > I have to agree with Harry.  And after all, everything we do
> > has some cost of some sort.  In DIY electronics, it's some
> > cash spent for decent tools.  And as Harry points out, most of
> > them are one time costs.  At least things like oscopes last
> > a long time.
>
>Well, last a long time... I've found several scopes. One Philips (with
>two X inputs) sometimes doesn't give output. Another one (X/Y, 19"
>unit, quite big) never gives output, and one biggy (19", with weird
>inputs (X, Y, Z)) gives a very strange effect, it keeps in the middle
>with fluctuations in one direction (adaptable with knobs). Do you
>people have any clue of what could be wrong with these machines? And
>is it 'safe' to fix them when they're connected?
>
>greetz,
>Kasper

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