Re: Asteroids X axis problem

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.
>
> The 4016 has been replaced as it was faulty (total screen collapse in
> the X axis) so perhaps the TL081 or TL082 ?
>
> Perhaps even the AD561 ?
>
>> If you make the picture smaller, does the "vertical line" unfold in
>> an object?
>
> Sorry, Forgot to mention - the problem goes away if the picture is
> reduced to 'small to moderate' size in the X axis - if it's between
> moderate to large then the fault occurs.
>

If adjusting the x-axis size changes the results then the problem area
is around the X-Axis size control and related ICs or later (no schematic
on hand).

You did say that you tried a later board and no problem on the monitor -
that lets the monitor and power supplies out.

John :-#)#
>> Do you have a picture?
>
> Afraid not, not much to see really though, just a vertical line the
> height of the object as it passes through the edge of the screen (the
> object is still drawn okay though).
>
>
> Thanks,
> Phil
>
>
>
>>
>> -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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>
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