HudsonArcade
Well-known member
The pong ball, which is visible in the demo mode, is not visible during game play. Omar had speculated that there is a crystal on the board. That this crystal may be bad, changing the frequency, which would possibly make the ball not visible. The crystal part number is Scm-18 the manufacturer is Sentry.
There is a crystal on the board, and if were bad you'd get no video whatsoever. All pong clones I've seen used a 14.318Mhz (4x colorburst) crystal.
There's an entire block of TTL chips responsible for drawing the ball. In other pongs, the ball is only gated by the screenblanking -- attract vs. non-attract mode doesn't affect it directly.
Anyone have any ideas for me? Is Omar correct? If so, where can I get a 50 year old replacement crystal from?
For the most part, crystals are crystals.
Looks like a standard HC-49 package.


