Joust - garbled screen

bobwired

New member
Joined
Sep 16, 2010
Messages
85
Reaction score
1
Location
Ft. Lauderdale, Florida
Hello everyone, I have a new problem that I know someone on here can help with. Joust, original dedicated cabinet. Started off with horizontal white line. After much repair to the monitor chassis, upon first powerup I got a bunch of bad ram codes and a non working monitor. I ordered from the parts from bob roberts and corrected the ram issues. Shotguned the monitor chassis until it finally worked. I finally have an image, but it is all jumbled up. Any ideas? Did I screw something up when I replaced the ram chips?
 
What does it look like when it goes to the game? or the rest of the attract mode?

ken
 
RE:

The only legible text is the joust logo on the attract screen. The LED display says 0. Ive attached photos of the various screens if that helps. Thank you.
 

Attachments

  • Diagnostic LED Display.jpg
    Diagnostic LED Display.jpg
    96.4 KB · Views: 19
  • Startup.jpg
    Startup.jpg
    79 KB · Views: 22
  • Attract.jpg
    Attract.jpg
    90 KB · Views: 25
  • gameplay.jpg
    gameplay.jpg
    87 KB · Views: 24
That looks like either:
a) the address decoding chips for the 'special chips' has gone wonky, or
b) one or both of the 'special chips' has gone bad, or
c) the video address chips have gone bad.

Less likely #3 or the Joust logo would have been messed up as well.

The logo is drawn by the CPU directly into the video RAM. The text and the background and foreground images are drawn by the 'special chips'.

A fix could be as simple as reseating the special chips and unplugging and replugging the ROM boards connector.

ken
 
tTank you Yellow Dog

You were right, it was the special chips. I pulled number 1 and there were 2 pins that were bent over and not in the socket. I've worked so hard on this cab, thank you so much!
 

Attachments

  • Joust Fixed.jpg
    Joust Fixed.jpg
    89.7 KB · Views: 23
Back
Top Bottom