Re: Asteroids X axis problem

On Thu, Mar 11, 2010 at 11:15 AM, <arcaderelics@irongiant.org.uk> wrote:

> I can't unfortunately see any faults when I 'scope out the signals.
When you "scope out" which signals? If the output (X&Y) looks good, then
you're looking at a monitor problem.

Either way, it sounds like a problem in one of the analog sections (monitor
or board), as in a signal clipping.

If you make the picture smaller, does the "vertical line" unfold in an
object?

Do you have a picture?

-Mark

> Just been fixing up my first Asteroids board for ages - multiple problems,
> all now fixed ......... except for one.
>
> Whenever an object gets to the far left or right edges of the display it's
> still drawn okay BUT as the object passes through the edge it makes a
> vertical line at that edge where the object is passing through - the line is
> same 'height' as the object too.
>
> Now I've seen something similar before which was caused by a problem with
> the UNMDACX12 signal, but in this case that's not the problem as changing
> the relevant chips (7404 at H10 and LS191 at C9) doesn't fix the fault.
>
> This is an early Rev 2 board.
>
> Could of course be the AD561 DAC, or the TL081 or TL082 in the X axis
> output circuit, but is there anything else that I've missed before I go
> swapping out multiple chips? I can't unfortunately see any faults when I
> 'scope out the signals.
>
>
> Thanks,
> Phil
>
>
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Received on Thu Mar 11 13:13:49 2010