VT-100 BNC jacks

[Tony Duell]

> 
> On Wednesday 21 January 2009 21:14:32 Tony Duell wrote:
> > There were some small 5" portale TVs sold in the UK a couple of years
> > back. Maybe a CRT from one of those could be shoehorned in.
> Ok,
> 
> I am going to have to take this thing apart and get some part numbers 

My experience with replacing 9" and 12" monochrome CRTs is that the part 
number is not that helpful. Well, obviously if you can get the same part 
again it'll work, but so will an awful lot of other types.

The things that have to match up are : 

Screen size, but only so you can fit it in the case :-). You can use a 
slightly larger or slightly smaller CRT with no prolems

Deflection angle. Most 9" and 12" mono monitors/terminals use a 90 degree 
deflection angle CRT. I don;t know what yours is 

Neck diameter. There are 2 sizes, you have to get the right one for many 
reasons. First the yoke must fit -- deflection yokes are a lot less 
generic than CRTs, so you keep the original yoke.

Seocnd, the neck diameter goes with the ase type. The large neck CRTs 
have a B8H base (a bit like international octal, but with thinner pins 
and a larger locating key). The small neck CRTs have a modified B7G base 
(like a 7 pin miniature valve, but with the pinch-off tube in the middle 
of the circle of pins).

And thordly, CRTs with large neck/B8H base tend ot hav 6.3V heaters, 
those wit the thin neck/B7G base have 12V heaters. Again, yopu need to 
get this right for ovious reasons.

The pinouts for a given base tpye seem to be standardised, and the 
elctrode voltagea for CRTs of similar size are likely to be 'near enough' 
that you'll get something recognisable on the screen.

-tony