Author Topic: Two 68B09EP in a Sega pinball, Q and E are in paralel?  (Read 423 times)

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Offline powerchisper

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Two 68B09EP in a Sega pinball, Q and E are in paralel?
« on: March 30, 2019, 03:55:22 pm »
Hello friends.

Still trying to fix the Independence Day Pinball.
When I turn the machine on, all the lights in the playfield flash, on and off. Everyone in the internet says this is a communication problem with the ROM, RAM , etc.

I did an experiment.

The main board has two 68b09EP processors, one for the audio and  the other one for the game code itself.
If I swap them, there are not even blinking lighs, so I suspect that the audio's 68b09 is not working.

My question is...is it possible that the sound cpu being bad can keep the machine from booting the game ?

I saw the schematics and  Q and E clock signals are in paralel to both processors, I don´t know if this is normal.
Also noticed that AVMA signal is always high, don't know if this is good or bad.

Got to this point thank to your help, I don´t have an oscilloscope, only a logic probe with 3 leds.

Any hints on this ?

Thank you in advance and, once again excuse me for my English I learnt from Beavis and Butthead.
 

Offline james_s

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Re: Two 68B09EP in a Sega pinball, Q and E are in paralel?
« Reply #1 on: March 30, 2019, 04:34:35 pm »
I don't think I've ever worked on a Sega pinball but in most machines the sound board is a completely separate subsystem and the game will boot and run without it connected at all. If the two CPUs are the same and swapping them changes the behavior then that's a pretty good indication that at least one of them is bad.
 

Online floobydust

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Re: Two 68B09EP in a Sega pinball, Q and E are in paralel?
« Reply #2 on: March 30, 2019, 04:59:20 pm »
If swapping the CPU changes things, then you have a bad CPU or a socket/connection issue. Be careful of ESD, so you don't zap things handling the boards.
The main CPU might hang waiting for a response from the Sound CPU, and that is what you are seeing.
 

Offline stj

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Re: Two 68B09EP in a Sega pinball, Q and E are in paralel?
« Reply #3 on: March 31, 2019, 10:53:20 am »
i dont know about whitestar or whatever you have,
but on videogames it's common for the cpu's to come out of reset in sequence.
so if the sub cpu does not start the main cpu will sit in reset waiting forever.
 

Offline powerchisper

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Re: Two 68B09EP in a Sega pinball, Q and E are in paralel?
« Reply #4 on: March 31, 2019, 03:09:36 pm »
Thank you all for your response.

I already ordered a new cpu ( 68B09EP ) , it is not so easy to find.
As you see I'm not an expert in this specific subject, but I have read everywhere that this system is sooo delicate !!!.
It seems that it goes into perpetual reset even at the minimum trace resistance, bad sockets, etc.

The reset is done by a DS1232, and it needs to be constantly fed with a bank select signal  which depends on the adress bus.
If this signal does not oscillate at a minimum speed, it will shut down the system.

I will keep you informed, any other hints are welcome.
 


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