I can help you with the vertical line problem. (maybe)
First check, with a scope, the inputs to the DACs. One will
be held low all the time. This creates a vertical space where the
vectors jump into a "fluid, I don't know what to draw" kinda space -
about a inch in height. If you're not sure what you are doing (go
from the XDAC to the YDAC to see if the signals are the same or
not - while in TEST mode).
If a signal (DAC1-10Y etc) is low ... track it back to the LS157s.
This is what died on one of my AST DEL boards.
SPW
> -----Original Message-----
> From: Andrew Wilson [SMTP: ]
> Sent: Wednesday, November 11, 1998 4:10 PM
> To:
> Subject: Re: Reversing X output on B/W vectors
>
>
> > Hey all, I'm pretty new at this and came across a perplexing problem.
> >I picked up an Asteroids with monitor problems. The monitor works but is
> >very dim with the brightness all the way up and the vectors are huge on
> >the screen even when turned all the way down at the board?
>
> These sound like classic symptoms of old caps - I'd install a cap
> kit (they
> are only $4.95 from http://www.randyfromm.com/Zanen.htm)...
>
> > I have two spare monitors that both came out of Omega Race's. They
> >both work on the asteroids but, The screen is backwards (I guess cause
> >Omega Race uses a mirror) Is there an easy way to reverse this?
>
> Just reverse the +/- X leads to the monitor (or Y leads, whichever
> is
> swapped). I think you can also tie one of the inputs on the Asteroids
> board to 5V to
> do the X inversion (see the pinouts - I think PIN 19 on the solder side is
> the INV X
> lead).
>
> > They also both have vertical lines about 1 centimeter apart all the way
> >across the screen that create a small ripple effect as the vectors pass
> >through them. Seems odd that they both have this problem. any thoughts?
>
> Can't help ya ;(
>
> Drew
>
>
