Atari Pong

From: teeray <teeray_at_earthlink.net>
Date: Wed Mar 14 2012 - 20:31:14 EDT

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


--------------------------------------------------------------------------- ** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org ** Please direct other questions, comments, or problems to chris@westnet.com Received on Wed Mar 14 20:31:23 2012