Re: Atari Pong

It looks like the modification is to lengthen the coin switch pulse. The
capacitor lengthens the pulse and the resistor reduces the current spike
when the coin switch first activates. The mod also helps to cause your
problem.

I need to find where /srst gets inverted to srst, it isn"t anywhere on my
schematic. Maybe another mod with a capacitor from +5 to srst is in there?
On Mar 14, 2012 7:31 PM, "teeray" <teeray@earthlink.net> wrote:

>
> board is now working after replacing a few IC's but on power up
> the score reads 1^ turn the "^" upside down like a "u" but raised up to
> the top.
> Both left and right scores display this.
>
> look at 7448 datasheet when it has an input of 12 binary 1100 this is
> what will
> be displayed and sure enough the 7490's are outputting 1100.
>
> Start game and it sets score correct and works correctly, when game over,
> score
> is still fine. So looks like on power up the score counters 7490's are
> not getting reset.
> I don't see a power up delay reset in the schematics.
>
> This board also has a mod. pin 10 from edge connector (coin) has been cut
> and
> a 27 ohm resistor inserted between edge connector pin 10 and IC (C9) pin
> 12 with a 270uF 6.3V cap
> connected between (C9) pin 12 and +5 volts.
>
> Here is a picture of another board that I found on the web, that has the
> same mod.
> http://www.andysarcade.net/pix/AA00993.JPG
>
> Can anyone tell me what this mod is for ?
>
> Thanks
>
>
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Received on Wed Mar 14 21:57:12 2012