Re: Vector Hardware

You might be looking at apples and oranges here. The zooming rectangle is normal,
but might not have been in the earlier version of the software. For example, the
earlier software showed a hex code as you turned the spinner while later software
had a vector that spun as you turned the spinner (this is on the switch test page).

Mendel Pearl wrote:

> Okay, now I am a bit confused.
>
> I have laid my hands on one more board, which is the newer version, with only
> half of the number of PROMS.
>
> I suspect the DAC08 to be faulty (or circuitry around it) because my basic
> picture is right (in the test screen with the large 'plus' sign, The AM6012 DAC
> output is right (on my o-scope)) compared to that of a working board. However,
> the DAC08 adds a signal causing the display to be offset and it shows a large
> rectangle zooming in over and over.
>
> But when I run this test on the older, working Tempest board, There is ONLY a
> plus sign and NO zooming rectangle.
> Also, when I check the DAC 08, it gets NO data on all its data lines, and adds
> nothing to the output except the signal coming from the 'Vector' signal (added
> throught the 2 transistors) but in the newer, defective board, the DAC08 is
> feeded with data and I can see an extra square wave, increasing and decreasing
> it's amplitude (And thus causing the rectangle I guess).
>
> Is this normal (the linear and binary scale test maybe?) for the newer board or
> is this just someting completely weird?
>
> Jess Askey <jess@magenta.com> on 11/12/99 07:17:35 PM
>
> Please respond to vectorlist@lists.cc.utexas.edu
>
> To: vectorlist@lists.cc.utexas.edu
> cc: (bcc: Mendel Pearl/Matra exiTel/nl)
> Subject: Re: Vector Hardware
>
> The DAC08 is performing the linear scaling for the vector generator. the vector
> counter
> can do the binary scaling (preset sizes). But if you want and object to change
> size
> gradually you need the linear scaling.
> If you watch the linear scale test, you see a box growing gradually out of the
> center. I
> think the way is works is that the output of the DAC08 is the input of the
> AM6012's +ref
> or something. Essentially, the DAC is a linear control of the XY DAC's positive
> rail.
> If you watch the binary scale test, you will see the box jump from on scale
> factor to
> another. It can't do smooth scaling.
>
> I did't thing that Tempest had linear scaling? Am I thinking of the wrong
> DAC-08?
>
> jess
>
> Mendel Pearl wrote:
> >
> > Yes! Finally I got my Tempest AVG working again!
> >
> > The problem turned out to be the MC1495 multipliers, which was a real hard job
> > tho find these here in Holland.
> >
> > My other Tempest board still has a problem with the X defection, the Y is
> > working after replacing the current/voltage opamp (TL082) , thanks Rodger!
> This
> > little baby indeed caused the virtual ground to be not 'grounded' :)
> >
> > Maybe somebody could help me out on this one:
> >
> > What is the DAC08 doing in the circuit? So far as I can see from the
> schematics
> > and MC1495 datasheets, it seems to me that the MC1495 multipliers perform the
> > east-west correction (pincushion).
> > As you can see from the circuit, the output current of the DAC08 is directly
> > summed to that of the XY DACs.
> > Maybe somebody could shine a light here? I am really trying to know how the
> AVG
> > functions exactly...
> >
> > Thanks!
Received on Sat Nov 13 11:17:45 1999