3 May
2013
3 May
'13
3:44 p.m.
On Fri, 3 May 2013, Geoffrey Oltmans wrote:
The thing I dislike about that chessis is that it's 'hot'. It's directly
conencted to the mains. That's why the US version of the visdeo input
PCB (which fits in place of the IF strip PCB) in the TRS-80 M1 monitor
has an opto-isolator on it, The driver for that optoisolaotr needs a +5V
feed from the computer, which makes it not so easy to use with other
machines.
The European verion, btw has a step-down _isolating_ transofrmer on the
mains input to covert 220V maisn to the 115V needed by the TV chassis. So
the video input PCB is just a transistor amplifier with no opto-isolator.
Incidntally, I maanged to get one of those monitors to do MDA scan rates
by tweakign the hold controls. It wasn't very happy, but it did produce
an image which was good enough to see there was something in the vidoe
signal. I would not want to runt it at such rates for very long.
It would be nice to figure out a good common TV
set that could be adapted
to Analog RGB or CGA.
For B&W, I'm partial to the 1970s RCA, like the one on Al Bundy's kitchen
counter. Pull the tuner out, convert to composite input, put a grommet in the volume control knob hole for input cable, and
paint it gray. Then you
You men the 'V' over that hole doesn't stand for 'video' :-) (Yes, I
know
the volume cotnrol was there in the TV version, somewhere I have the M1
monitor service manual which is the RCA TV manual with some bits missed
out and an extra section for the video input PCB).
have the TRS80 model 1 monitor. Instead of leaving
the tuner space
vacant, you can mount a full height (or 2 half height) 5.25" floppy there.
(a piece of mu-metal helps).
Don Lancaster wrote a few books on making monitors out of TV sets.
Oh.
You probably meant something current.
A few years ago over here there were some cheap 5" B&W TVs (with an AM/FM
radio built in). They run off intenral batteris, or a 12V input (a car
battery cable and mains adapter were genreally suppleid with said sets).
I bought a couple with the intention of addign a compositie input socket,
only when I got them home did I realsie that said facility was standard.
Although I'd not want to sue a 5" montior all day, they are very handy on
the workbench for g]checking if a home compute is producing any output.
-tony