Questions - Universe/68, HP-9134A,VT420 composite video

[Patrick Finnegan]

On Sunday 17 April 2005 08:06, David Comley wrote:
> - I'd like to use a surplus VT420 as the display for
> the DEC 350 Pro I picked up. This will entail
> identifing a point on the VT420 schematic where I can
> inject the composite video signal from the 350. So I
> need the VT420 schematic. Does anyone on the list have
> one ?

First off, before you go around modifying VT420s, you may want to test 
the Pro first.  The 'composite' output of the machine nicely matches 
NTSC (RS-170) composite signal specs, so you can hook the output 
directly to a TV with a composite input.  Beware that the TV will 
overscan the signal a bit, but you should see *something* when you 
first power up the Pro to indicate that it's at least somewhat 
functional.

As far as the VT420 schematics, I don't have any, but you might try 
finding a VT220 to use, or a professional NTSC video monitor.  I've got 
a few of each and would probably try those first... the VT220 isn't too 
different from the VR201 that should go with the Pro, and is probably 
easier to modify (it even has the composite video output on its back, 
so you might be able to trace what to do without schematics event).

Pat
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