[Coladam] COLECOVISION CONSOLE PROBLEM

Rich Drushel drushel at apk.net
Fri Jul 22 15:35:57 CEST 2011


On Fri, July 22, 2011 12:35 am, kevin laskowski wrote:

> I just bought a new Samsung 450 32" lcd. I hooked up my coleco console
> to it, and it comes on but theres a white snowy bar that flashes on
> the top and bottom of the screen. It also makes a clicking noise
> through the speakers when it flashes. It works fine on my old 20" tube
> set?
>
> Any thoughts? Thanks

     TV sets with digital NTSC tuners or inputs are very intolerant of
signals that are not exactly up to spec.

     In the old LEGO robot course I used to teach, we had a roving spectator
robot, Cambot, with a pinhole TV camera and short-range VHF transmitter
(channel 3 or 4, selectable), to allow the audience to see a robot's-eye view
of the competition.  An ordinary rabbit-ear antenna was used to receive the
signal on a VCR, whose NTSC outs went to a 12" Commodore color monitor).
Sometimes there would be interference from other robots, but the TV picture
was pretty good, as was the VCR playback.  However, playing the VCR back
through a digital camcorder, to either re-record to digital tape or else
use the play-through to FireWire so I could import the video into iMovie
and iDVD, the digital encoding would always stop at the slightest bit of
interference or flutter in the original VHS tape.  This was with several
different models of Sony camcorders.  No problem at all doing a VCR-to-VCR
tape duplication.  Interestingly, the 32" tube TV we had in the lab could
also display the VCR output with no problems, but it could not receive
the Cambot TV broadcast directly through the rabbit ears without constant
picture breakup.  Whatever the TV tuner circuit was in our VCR was more
tolerant than the known digital TV tuner circuit in the 32" TV.

     The upshot of this is I have 19 semesters' worth of robot competitions
on VHS that, with equipment available to me, I have not been able to
reliably digitally encode to get it all onto DVD.  Maybe newer VHS-to-DVD
direct converters are more tolerant.

     If you have shielded cables, instead of the cheap stereo speaker kind,
you could try them.  Or try a long cable (15 feet or so) to make sure that
interference from the console is not a problem.  Both the ColecoVision and
the ADAM can radiate all kinds of spurious EMF.

     The last thing that I can suggest would be to run the ColceoVision
TV output (with game switch) into an older VCR with TV inputs and NTSC
outputs, then pipe the VCR's NTSC out into your Samsung TV.  Maybe that
will do some signal conditioning that improves the TV output.  For our
robot competitions, we used Radio Shack video amplifiers/splitters (i.e.,
one video/audio signal in, up to 3 copies out) in each camera line, to
feed monitors and multiple VCR decks.  Those seemed to have some video
stabilizing ability; at least, they didn't seem to degrade the signal.
Ten years ago, they cost about $25.

     There is a ColecoVision hack to make it output NTSC and separate
audio, the way an ADAM system unit does.  I don't have a link at the
moment but I have seen it around.  You could try this and see if it
improves the video output quality.

     *Dr. D.*

-- 
Richard F. Drushel, Ph.D.            | "They fell:  for Heaven to them no hope
Department of Biology                |  imparts / Who hear not for the beating
Case Western Reserve University      |  of their hearts."
Cleveland, Ohio  44106-7080  U.S.A.  |         -- Edgar Allan Poe, "Al-Aaraaf"




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