Jump to content
IGNORED

Ultra Pong not switching to 2 player mode


drurywoodson

Recommended Posts

I have an Ultra Pong that is mostly working, but it is stuck in the 4 player mode and will not switch to the two player mode no matter how many paddles are not plugged in.  Also, the Right B paddle will not move the cursor.

 

Here is what I have tried so far:

1)  All 4 of the paddles will work in any of the Left A, Left B, or Right A jacks, so I know it is not a problem with the paddles.  They all range from about 0 to 800 kOhms.

2)  I have replaced all four of the paddle jacks.  The jack in use switch is good in all 4 jacks.  Each of the 4 jacks can read the paddle potentiometer.

3)  The paddle sense line at the back of the jacks is VCC if any of the 4 jacks are unplugged, and is disconnected from VCC if all 4 paddles are plugged in.

4)  The signal from the right b jack is present at pin 13 of the pong chip, and I can correctly read the resistance value from there.

5)  I changed out the chip with one from a water damaged console, and I get exactly the same problem with the other chip.

6)  The 68nF cap hanging off the Right B line tests as 71 nF, which is within spec.

 

 

The circuit is really simple, and I am out of ideas.  Does anyone have any suggestions?

Link to comment
Share on other sites

  • 2 weeks later...

I have done more research, on it, and it is really weird.  With everything turned off, the paddle resistance reads properly in the circuit.  When I apply power, the paddle line is stuck at a high voltage.  I would guess it is a problem in the pong chip,  but I have two of them and they both do the same thing.  Has anybody else seen this failure mode?

 

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...