HP9836C colour alignment (grey scale tracking)

Tony Duell ard at p850ug1.demon.co.uk
Sun Sep 28 12:20:42 CDT 2008

> I would be reluctant to float a delicate instrument at several kV. 

Well, I certainly wouldn't use any form of electronic meter (digital, 
amplified analogue, etc) for this. I was thinking of using a plain moving 
coil meter, possibly with a shunt resistor.

> Can't this damage the instrument through corona discharge around some of 
> the internal components?

Hmm, possible I suppose. Maybe I chould encase it in a metal guard 
electrode, connected to a 25kV supply. Or maybe not...

More seriously, I haev come across moving coil meters being used at quite 
high voltages wrt ground (not as high as this, but 10kV or so). They were 
mounted several inches behind a thick perspex window -- this was not a 
'lash up'. 

I would be prepared to try it, given a fairly inexpensive meter movement.

For those wondering what the current state of this monitor is, I've 
cleaned up all the case parts and put it back together. It still works 
(so I didn't do any damage taking it apart), although there are still red 
fringes to the right of (say) white objects. I am not sure if this is a 
convergence problem or due to the change in video amplifier response due 
to that open-circuit 12.4k resistor which I've not replaced yet (I wanted 
to make sure the monitor still worked after I'd finished pulling it about 
before changing anything).


> Philip.

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