Re: Need a little assistance on Death Race Monitor

Ball Brothers! They made a damn fine monitor back in those days, used in a lot of
computer terminals. (And, no, they are no relation to the canning supplies people,
different Ball all together.)

Matt Rossiter wrote:

> A programmable transistor? I've never heard of that before. The choke coil that
> looks like a resistor is new to me too. This monitor has had all kinds of
> surprises. Ball Brothers, apparently, is the same company that makes Jars and
> lids. I had no idea my mom's homemade Jam would have some relation to my death
> race.
>
> Anyway - I've been getting some suggestions from other people privately as well -
> and Q112 seems to be a likely suspect. When I get home I'll get the scope out and
> tell you if I'm getting some pulses.
>
> Thanks!
>
> Matt
>
> Rodger Boots wrote:
>
> > Wow, a PUT (Programmable Unijuction Transistor) oscillator! THAT's something
> > you don't see much.
> >
> > The "base" (actually the gate) of the PUT (Q112) should be narrow sync pulses
> > (is any sync is being sent to the monitor) and across the coil (L101) will be a
> > 60 Hz pulse or ringing waveform. Neither will probably read anything on a
> > meter, you'll need a scope.
> >
> > If you think the PUT may be bad, it crosses to an NTE6402.
> >
> > Matt Rossiter wrote:
> >
> > > I'm a little stuck on a problem here. I'm not getting any vertical
> > > deflection. All I get is a thin horizontal line - within that
> > > horizontal line, I can see things moving back and forth. I was
> > > wondering if someone could look at the schematics here
> > > ftp://ftp.rossiters.com/pub/ball-brothers-TG20-23.jpg.
> > >
> > > The large vertical deflection transistor is fine. If you look on the
> > > schematics at the section labelled "vertical oscillator" - at the base
> > > of Q112 I'm getting zero volts - plus I'm getting zero volts where the
> > > the choke is below it. Shouldn't I be getting some kind of reading
> > > around that choke? Just looking for some ideas - I'm not exactly sure
> > > what the purpose of that choke coil is.
> > >
> > > Thanks...
> > >
> > > Matt
> > >
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Received on Wed Jul 11 09:33:42 2001