VT-100 BNC jacks
ard at p850ug1.demon.co.uk
Thu Jan 22 13:01:36 CST 2009
> 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.
> 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.
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