Re: Tempest vector distortion

I didn't realize that disabling the added protection circuit was so
easy. Certain Major Havoc stages on my ZVG cab were displaying the
fold-over issue, similar to Ken's video. It was only with P329 def
boards.

Lifting diodes 809-812 was the cure....

thanks Zonn!
James H

On Wed, Aug 10, 2011 at 5:12 AM, Zonn <mlists@zonn.com> wrote:
> 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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>>
>
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Received on Wed Aug 10 08:59:21 2011