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(Topic ID: 203975)

Data East CPU not booting help

By Bax1

2 years ago

Topic Stats

  • 15 posts
  • 3 Pinsiders participating
  • Latest reply 2 years ago by Bax1
  • Topic is favorited by 2 Pinsiders


#1 2 years ago

so picked up a cpu for my r&b that came out of a simpsons. I did the jumper and not getting it to boot. replaced rom sockets and checked continuity throughout the board. I get the pia light staying on still. so bought a logic probe and started poking around. so checking the pia's, most of them have the same signals except a couple of them. pia at 5f pin 10-18 are low and nothing at pin 19. pia at 8h no signal at all from pin 10-17. could I assume both of these are bad or due to 5f being for coils have low signals due to switch not being activated? new to figuring out board work but having fun learning.

#2 2 years ago

Also on pia 8h pin 1-9 shows low on logic probe

#3 2 years ago

Docent Electronics sells the Data East factory MPU diagnostic chip that can test the PIAs. They have it listed in their ebay store.

#4 2 years ago

I have Marco's test rom but game needs to boot.

#5 2 years ago

calling all data east board techs

#6 2 years ago

Did the board boot up as a Simpsons MPU?

#7 2 years ago

don't know. bought it untested.

#8 2 years ago

Always good to know if it boots up before doing anything. Only need the power connector connected to see if it boots. If you knew that it booted with the Simpsons ROMs and now not R&B ROMs, that would tell you it is either a jumper issue or a ROM chip problem. Can you post a picture of the MPU?

#9 2 years ago

grumpy have any thoughts on this board?

#10 2 years ago

I do have the original board but it had bad battery damage. cleaned up the damage and it still has some funky issues so I picked up this board. I have got the new board to boot a couple times but it is not consistently booting. I think there has to be an issue with one of the 6821's

#11 2 years ago

Can you check and report the (5v, 12v, and -12v) voltages you measure on the top right of the power supply?

#12 2 years ago

in machine is good. on bench I just have 5v and ground hooked up.

2 weeks later
#13 2 years ago

So back to messing with this board. I changed 8H pia and it has same reading on logic probe as previous pia. Pins 10-17 read nothing but have continuity

#14 2 years ago

Anyone have any ideas?

#15 2 years ago

bump for anyone?

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