Data East sound problem

[rich_j]

Hi,
I have a Data East Batman Forever.
I bought it with a sound problem.
When I first got it, it was repeating the final sound "lets flip for it"
After replacing all the Eproms, I found that the ribbon cable from the CPU to the sound card was back to front.
When I put the ribbon cable in the correct way, there was no sound at all.
I am suspecting with the ribbon cable the wrong way, the sound card was thinking it was receiving the "lets flip for it" command.

So I know that,
Speakers work, amps work, 80% sure the sound board works, eproms are seated correctly and ribbon cables are correct.
So I am thinking that it is the output from the CPU.
I have also gone into the sound test menu and none of the sounds play.

Does anyone know a way to test the output sound signal from the CPU?
I have the manual and can see there is a 6821 IC on the CPU whos output signal goes through a rack of 4.8k resistors and then through capacitors before the output connector.

Any help would be appreciated.

Thanks Rich

[MartyJ]

Rich,

Quite a cool game you've got.

Firstly what are your voltages like at the sound card?  You should be able to test these at CN2 on the soundboard.

You need to make sure you've got +5v, +12v and -12v

Has the power supply been rebuilt at any time?

[Caveoftreasures]

I have a Batman Forever and everything works fine. If u need any voltage measurements or anything looked at/compared to, let me know and I can try and see if I can help as well. 

[rich_j]

thanks for the suggestions.
CN2 voltages to the sound card are 4.95, -15.15, 11.45
Both at the power supply and at the sound card.

I think the sound card is ok as when the ribbon cable was the other way around, it was playing the end game sound.

Does anyone know a way to check the output sound signals from the CPU board?

Or diagnoise and elliminate areas that are working ok?

Thanks,
Rich.

[MartyJ]

Do you have a copy of the manual with schematics?

You'll need a logic probe was well.  I don't have a copy so unfortunately cannot even point you in the right direction to start.

[Marty Machine]

Besides the sound problem, is the game playable?

Have you tried triggering (fingering) every switch and target in the game? maybe one of them is struck closed, hence it being in the 'let's flip mode' ??

OR at least try a switch-test in the menu option....

The worst thing is spending all day chasing a fault that doens't exist, simply 'coz a switch is stuck on (or switch diode shorted). 


MM.

[dj10555]

You can test all the 6821 on the CPU board using Leon's test rom. You need to burn a copy of the rom, install this on the CPU board, make sure all connectors except for the power supply are removed or set the board up on a bench. Then with a logic probe you can see the outputs from the 6821 toggling. It is fairly common to have one or more ouputs die on one of the 6 x 6821 chips on the board. If you need to remove a faulty 6821 you need to be very careful of the tracks which run between the 6821 pins as there is only about a 1mm clearance.

Hope this helps.

[rich_j]

Marty,
The game plays fine. I can't wait to play it with sound !!
I have done a matrix switch test and found I needed to replace the 2 x PCB's which make up the opto ball sensor.
Every other switch works fine.

DJ,
Thanks for the tip on the Leon Test Eprom.
That will keep me occupied for a few weeks.... ;- )
I already have 3 x 6821's in the mail.
I was going to blindly replace them, but now I see I can run the Leon's test EPROM.

Rich

[beaky]

have you tried the sound test in the diagnostic test menu?

when you say the ribbon cable was back to front was it just one side of the cable or both sides?

it may be something as simple as a faulty ribbon cable. start with the basics and then move on to the test roms once all avenues are exhausted.

[rich_j]

Thanks Beaky,
Oh Yeah, I have exhausted all the easy avenues I can think of.
I have played with electronics since I was a kid. The ribbon cable was one of the first things tested.
None of the sound tests work. I think I have a failed PIA Peripheral Chip 6821
I am making a Leon EPROM tomorrow. Then I can check the outputs with a DMM.

Rich

[rich_j]

Hi,
After making the test chip i found that there was one of the output pins on the PIA chip that was dead.
I had to cut the chip off the board, de-solder each leg and then put on a piggy back socket. I put in a new PIA chip and the game started playing some sounds.
Now I can go into the sound test diagnosis and hear the tones play correctly and the music play correctly.

I still have a sound problem through. The voice sound tests do not sound correct.
They are a garbled digital noise.
I think the BSMT2000 chip is the one that plays the tones but can not see how to trace why the voice chips are not working.
Does anyone know how to test the operation of the U17 and U21 chips?
It looks like they all share the same bus as the BSMT2000 and go into U24 and U23 parallel to serial chips and then to the D to A.

Thanks  Rich.