Disabling pincushion on Gravitar, Black Widow, Space Duel

I did research this and found the historical documentation quoted below (thanks Matt). In reviewing the Tempest material and the Gr/BW/SD schematics, it would seem another method would be to lift pin 14 of the correction MC1495 (A/B11 and A/B12), or even remove the chip entirely. Using BW as an example, that would leave R181 connected to the 10v available at R204 instead of lifting it and connecting it to R182. It seems the original method pulls R181 off the YCOR and hooks in to XCOR instead, which being self-referential may be a stable 10v, but wouldn't it be 'better' to not generate the correction signal at all?

-Douglas
 

> From: Matthew Rossiter <matt_at_rossiters.com>
> Date: Tue Jul 17 2007 - 18:08:23 EDT
>
> Hi Brent,
>
> I haven't tried disabling the pincusion correction on a 'Space Duel, Gravitar, Black Widow' boardset, but the principle should be the same.
>
> http://games.rossiters.com/Black-Widow-p19.jpg [1]
>
> http://games.rossiters.com/Black-Widow-p20.jpg [2]
>
> You can see on Page 19 of the Black Widow Schematics that the X-Correction output is coming from A/B 11 pin 14 and going to C12 pin 4 on page 20. You can also see the same for the Y-Correction output. What I remember having to do (on tempest) was to disconnect the X and Y correction output and apply a fixed voltage to the resistors going to pin 4, which would be on C11 and C12 according to the Black Widow Schematics. You might be able to try lifting one end of R181 and R205, which would be the ends coming from pin 14 of A/B 11 and A/B12, and connecting them to a 10 volt source as I did with Tempest. Then after that you'd want to adjust the X and Y Lin pots with the cross-hatch pattern turned on. At the moment I don't have the ability to test this first, but that's what I'd do.
>
> Has anyone else tried this?
>
> Matt
>
>> On Tue, 17 Jul 2007 11:24:11 -0700, "Brent" wrote: 
>>
>> Hello Matt,
>>
>> I came across this article by you.
>>
>> http://www.ionpool.net/arcade/tempest/tempest_disable.html
>>
>> I have an Amplifone monitor and Space Duel, Gravitar, Black Widow boardsets that I am using with it. But of course there is pincusioning with these boards.
>>
>> My question is do you know how to disable the disable the pincushion correction on these board?
>>
>> I know that they all have the same pinout (mostly, as they all work with a Space Duel harness, except for the controls of course). And Gravitar and Black Widow use the same boardset just different roms.
>>
>> Or could an adapter be made of some sort to put inbetween the boardset and the harness?
>>
>> This is for a very special project that I am working on. Thank you for your time.
>>
>> Brent
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Received on Wed Apr 4 10:40:41 2012