Ok - gota little excited and didn't read the email carefully. Ignore my
last post.
:)
Matt
_____________________________________________________________________
On Tue, 21 Dec 1999, Matt Rossiter - Verio Southern California wrote:
> I've never tried hooking up a cinematronics game up to an oscilloscope in
> XY mode.
>
> Anyone care to explain where the X Y and blanking points might be? Can
> you hook this up directly from the CPU board? I always thought it would
> have to be done from the monitor since that's where the digital/analog
> circuits are - which would probably be a waste of time since the purpose
> of the oscope would be to take the monitor out of the troubleshooting
> equation.
>
> Ya caught my attention here.
>
>
> Matt
>
>
>
> _____________________________________________________________________
>
> On Tue, 21 Dec 1999, Simon Whittam wrote:
>
> > When I started collecting the first deal I made was with
> > Dave Whitman in NC. I drove a cube van down there from
> > Ottawa and picked up five VECTOR games. Luckily for me
> > I had business in RTP and convinced my management that
> > the cube van rental would cost the same as the return first class
> > air tickets. That was two years ago.
> >
> > Since then the Asteroids, Asteroids Deluxe, Battlezone,
> > Armor Attack UR have been working on and off but for the most
> > part were all easy fixes (LS191 counters in the Asteroids, ROM
> > reseating in the AST DEL, cap kit in the BZ and ROM reseating,
> > and power supply repair (723) in the AA).
> >
> > The fifth game was a Armor Attack CT which he gave me for
> > $50US (complete with extra boards but not working). This has been sitting
> > in my
> > basement for all this time and was dead until a couple of days
> > ago. Cosmetically it is very nice (8+/10 with some glass scratches) and
> > since I had never seen one
> > of these before it seemed like a good deal (similar one on Ebay recently was
> > about $600US??).
> >
> > SYMPTOMS: No picture. CPU board known good. PSU tested good.
> >
> > Fix #1: Replaced blown 47ohm resistor and 2n5320 in vertical drive (R118,
> > Q108).
> > Fix #2: HV supply needed replacing (no voltage).
> > Now I get a long (length-wise) line on the display) => vertical
> > deflection
> > still not working.
> > Fix #3: Replace heatsinked power transistors 2N5878/76 and pre-drivers
> > 2N5320/22.
> > [Unfortunately these tested well in and out of circuit and were only
> > found bad by
> > guess-work and substitution]. :-(
> > Now I get a half-screen (top only) squished squiggly picture (made
> > of segments) which
> > seemed correct horizontally but zigged-zagged vertically downwards
> > from the drawn object.
> > Fix #4: Now I get the scope out and check the DAC output at the TL081s. I
> > see a perfect copy of the game in XY-mode (comparing outputs of
> > TL081s) so I know the DACs/analog switch
> > and op amps are working OK. Using XY-mode to debug an XY monitor
> > ... go figure?
> > Fix #5: I go to the collector of Q104 (vertical) and keep the scope in XY
> > mode (knowing
> > that the horizontal circuit is OK). And the scope shows me the
> > exact image that
> > the monitor is displaying (though R-L inverted). Woo hoo!!
> > Something is wrong at this part of the amplifier.
> > NOTE: Schematics note that shown waveforms at TL081/Q104 etc are
> > with Yoke removed ... I didn't bother doing that.
> > Fix #6: Replace Q104. Tweak the gain and linearity POTs. Now she works
> > perfect!!
> >
> >
> > SUMMARY: Using the oscilloscope through the circuit in XY mode might help
> > you to
> > debug the monitor faster than a one-by-one point-by-point pin-by-pin
> > analysis.
> >
> > Turned out to be a pre-Xmas present to myself (two years after the fact I
> > guess).
> > I hope this helps someone else fix their VectorBeam/WG XY monitor one day.
> >
> > SPW
> > Kanata, On
> > CANADA
> >
> > p.s. The CT monitor is nice a crisp on all drawn vectors. My UR monitor,
> > however,
> > has the player tanks kinda fuzzy. Any ideas what causes that? The text
> > and 'copter
> > are cleanly drawn.
> >
> >
>
>
Received on Tue Dec 21 13:38:26 1999
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