9 Oct
2007
9 Oct
'07
2:12 p.m.
First, the CRT in the VT100 is a M31-340W.
On Mon, 8 Oct 2007, Tony Duell wrote:
I have, alas, no idea if/when it was changed. I can try going back
through old books to see if anything turns up.
Not according to my 1988 Philips CRT Databooks!
The coding is explained as follows :
[...]
1988 is pretty new... Did they really change the nomenclature of the
tubes? I thought that I've not
seen a mgnetically-focuessed CRT since I repaired an _old_ Bush
TV. Old meaning System A, 405 lines. The focussing in that was controlled
Well, System A was broadcast until the 80s ;-)) According to my tube books one of the newest magnetic
focus CRTs for
television sets should be the MW53-80 and MW61-80 (around 1958/1959).
But they don't use fixed magnets, instead a focusing coil is used.
Some UK TVs did that too. Often the focus coil current was the cathode
(or anode) current of the audio output valve (!). But I've not seen one
of those for _many_ years, and certainly not in any computer-related device.
getting the
convergence and purity right!), but nonoe of the monochrome
monitor service manuals I've read mention magnetic focussing. I've never
seen a yoke with anything other than centering rings on it.
VT100 Series Pocket Service Guide, page 59/60.