Buster Bros - characters are jerky

neopolss

Well-known member

Donor 6 years: 2013, 2016-2020
Joined
Jul 16, 2003
Messages
3,222
Reaction score
110
Location
Topeka, Kansas
Thats the only way I can describe it. The characters and bubbles don't move smoothly across the screen, almost as if they are skipping a frame. So the effect is that they seem to jerk left and right. I'll try to get a video of it. Any ideas what may cause this? The game is still fully playable, just not very fun since my character is frame skipping.
 
In principle, it sounds like you may have a RAM issue (specifically part of video ram that has to do with sprite properties). I would put my money on the fact that the sprites jump at some power of 2, which would indicate that some bits related to their coordinates are stuck high/low and aren't changing properly, and when the higher bits do change properly the characters jump to their new spots.

Re-seat RAM chips, press around and see if flex changes anything, check for hot spots, duffed traces, etc.
 
I had that once... turned out to be poor solder joints on the single square PLCC surface mount custom chip.

Look at where the legs curl under the chip and solder to the board. You are looking for cracked solder or missing solder. I've seen both on that chip - it's kinda freaky to see missing solder on a chip from the factory. ;)
 
Found the problem this morning. Besides a filthy board, the problem would clear up instantly once I pushed in one of the rom chips. I'll hose the board down when I fix the suicide battery.
 
I agree to an extent, but you'd be surprised what a good cleaning will do for a board. I socket isn't always bad, but will act that way when it has seven layers of filth between the eeprom and the socket. I always start with cleaning my boards and letting them dry out, then start with resocketing and checking for further issues. Considering that many of my finds are in barns or basements, cleaning is always key to troubleshooting.
 
Hosing it down isn't going to help. If the chip is socketed it's a bad socket, if it's soldered then it's a bad solder joint.

Not necessarily. If it's a ROM next to that PLCC chip he could be flexing the board enough for the PLCC chip to make contact on a crappy soldered pin. ;)

RJ
 
Back
Top Bottom