Re: Tempest vector distortion

Assuming you have a P327 deflection board, lift one leg of diodes D805
through D808 (doesn't make any difference which leg, just lift one leg
from each of the diodes), and all your problems will go away.

D805 through D808 are part of a monitor protection circuitry that was
supposed to protect the monitor if the game board dies.

Worst design ever. Doesn't work worth a damn, and can really distort
vectors when what's being displayed is too close to the center of the
monitor, and there are no peripheral vectors being drawn.

-Zonn

On 8/9/2011 3:14 PM, Ken Sumrall wrote:
> Hello,
>
> We have a small arcade at work, and I recently got the cabaret Tempest
> machine
> there to work again. Basically I just pulled the logic board and
> reseated all
> the socketed chips and the interboard connector cable.
>
> It now comes up, stays up, and shaking the cabinet doesn't cause the
> game to
> crash. However, I'm seeing some vector distortion. When it displays the
> TEMPEST logo in the attract mode mode, near the end of the animation, the
> vectors foldover, and then (mostly) return to normal. You can see a
> video
> of it here:
>
> http://www.scrapheap.net/tempest/
>
> Also, on some levels (in particular, the one I call the staircase level)
> straight lines get drawn with a definite curve in them, and the screen
> tends
> to pulsate a bit with the size of the image growing larger and
> smaller. My
> first reaction is I need to work on the monitor, but then I thought
> maybe I
> need to adjust the X and Y size and position pots on the logic board.
>
> I also see some faint lines which I assume are the beam location being
> moved
> with the beam turned off. I assume I fix this by adjusting the screen
> brightness.
>
> Suggestions anyone?
>
> Thanks in advance for your help!
>
> ___
> Ken
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Received on Wed Aug 10 05:12:50 2011