Free: broken but possibly fixable sync-on-green monitor

[Tony Duell]

> I have a Viewsonic PT813 21" CRT monitor, a very high-end professional model
> that I was told used to cost $1800 new (1997), has both DE15 and BNC inputs
> and supports both PeeCee video and sync on green.  Unfortunately it is
> malfunctioning - the picture is smudged to the point of being totally
> unreadable.  It seems like some component in its circuitry went bad -
> I don't think it's the CRT - so it's probably fixable.

A word of warning to anyone who gets this... I had an Apple Mac+ that had 
a smeared display -- shaddows to the right of objects on the screen. Now, 
the Mac+ video circuit is pretty simple, but none-the-less I spent quite 
a time going through it, unable to find the fault.

The reason I couldn't find a fault in the video amplifier was that there 
wasn't one. It was the CRT. Low emission, I think. 

Most of the time, a smeared picture _is_ a fault in the video amplifier, 
though. But it may not be.

-tony