F1 Dream (Capcom) with sprite prob

[jammajup]

Hi all!

 

I have an F1 Dream on the test rig at the moment with a `foreground` sprite problem.The sprites appear to be drawn in horizontal strips/segments but every other section is drawn around two inches to the left of the true position like so..

 

 

I am currently checking a few 74 series ic`s near the many MCM2018N45 slimline rams, has anybody had something simular with these Capcom boards?,i do not look forward to changing my first slimline ram.

[Stingray]

A good first step would be removing any socketed chips one at a time, clean the pins and resocket them. I don't have any experience with that board though, this is just generic advice.

 

-S

[jammajup]

Hi! S

 

Yes that is always my first move,cleaning the ic legs with a pencil eraser before re-seating them

(also a good method for cleaning the edge connector).

Tom i will replace a 74LS374 (octal Flip-flop),it is receiving clock signals and the chip is enabled but the output is not switching in response.Failing that,if i can see nothing else suspicious i may have to change some rams.

[Cassidy Nolen]

I'm thinking RAM as well on that one. If you have an eprom burner, might be worht pulling the graphic roms and seeing if they are any good. Bit rot maybe? Seems more likely a RAM thing though.

 

Cassidy

[sebastius]

Looks familiar, i've got a similar problem with a capcom game I've got (Carrier Airwing). The problem was that I couldn't reach the chips on the bottom board with my logic analyser, so I replaced the bottom board and the game worked fine again.

 

Your problem is not a Bit-Rot one, maybe RAM, but I suspect RAM adress decoding or the buffer from the ram to the video portion which has an enable line. Maybe the buffer is faulty or the circuit that drives it.

 

Good luck!