VR241 Substitute

tony duell ard at p850ug1.demon.co.uk
Sun Apr 3 13:51:39 CDT 2016

> I could do with getting hold of a VR241, but these seem to be pretty
> unobtainable. So the alternative is to rig up an adapter of some kind to
> work with a VGA LCD, which also saves on space. I came across the following:
> http://www.vcfed.org/forum/showthread.php?38450-VR241-substitute-for-Rainbow
> -VT240-etc, has anyone else tried this with success?

If it's any help, the VR241 is a (US) TV rate monitor with analogue RGB inputs. It can
be switched between separate composite sync (on a 4th BNC socket) and sync-on-
green, with the Rainbow, Pro 300 series and VT240 it is used in the latter mode. I
would guess the DECmate also uses SOG.

Not that it matters here, but the original VR241 is a Hitachi chassis with features you
might expect from that manufacturer. The deflection circuit is based round a thick-film
hybrid module contain an IC for both oscillators and power transistors for the
vertical output stage. The power supply is driven (when running) from the horizontal
output stage, this means a ridiculously complex startup circuit...


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