Cookrace Bootleg Help

Stoog

Member
Joined
Apr 28, 2014
Messages
977
Reaction score
6
Location
Australia, NSW, Australia
Hmm need a little hand with this one

Boots up black screen somtimes does start up and work but missing ladders and platfoum sprites but thats another issue just need to fix what i wrote below

Now the werid part reset line working fine if i force it to reset as in turn it on and manually reset it i can somtimes make it boot but there is a still a issue when it goes through demo screen back to title screen then to demo screen it crashs and gets a stuck image going over cpu ram/roms all activity is just either stuck high or dead. its iike when it gets to that code in the boot eproms it tells to cpu to stop running or somthing on the data/address lines is causing it.

so far ill replaced a NE555 timer in reset circuit due to being very rusty and checked out any other parts which are fine. replaced boot ram, tried another known good 6502 cpu and reburnt the game eproms but still odd part is i cant work out why its so gone over cpu to rams and roms and cant find what is causing this unless its a timing isuue i really dont know

ive never seen this type of issue before where it crashs like that if i coin up the game i can play it fine for awhile so its a really good fault this one
 
Last edited:
FIXED

Turned out to be a failing 74LS367 and a 74LS04 on bottom PCB.

Both of these looked very bad on the scope after a few reboots from a cold start looked normal but afetr a while i noticed it slowly starting to drop in areas of the wave form.

Underneath the 04 i noticed some corrosion on one of the tracks. cleaned up and repair the tracked repaired the spite background (missing ladders/platforms fault i had)

Been running for a few hours on and off and had no issue so i say both of those chips were on there way out or just working enough to somtimes boot up

Still quite interesting that the game still some what worked
 
Last edited:
Back
Top Bottom