(Topic ID: 140373)

Bally SDB Causing Sound Issues

By stangbat

7 years ago

Topic Heartbeat

Topic Stats

  • 11 posts
  • 3 Pinsiders participating
  • Latest reply 7 years ago by stangbat
  • Topic is favorited by 1 Pinsider


Linked Games

#1 7 years ago

Game: Flash Gordon (this may not matter)

Symptom: With this particular SDB is installed one wrong sound is played when certain switches are triggered. Also the background sound will not restart at times.

Analysis: The game behaves fine when tested with four other SDBs I have on hand. It only misbehaves with this particular SDB.

My first thoughts were this is a data issue so I approached it that way. I initially suspected the 74L156 but it is fine. Finally after a lot of head banging and misdiagnosis I booted the game with ONLY J3 attached. J4 is not connected, so no data that is being passed from the MPU to the SDB to the sound board should be affected, but it still misbehaves as described above (wrong sound, no background sound at times). But if I hook up one of the four other SDB with only J3 attached the game acts fine.

Any help is greatly appreciated!

#2 7 years ago

In what manner does it misbehave with only J3 connected?

#3 7 years ago
Quoted from cody_chunn:

In what manner does it misbehave with only J3 connected?

The same behavior as described in the symptom of the above post, one wrong sound is played when certain switches are triggered. Also the background sound will not restart at times.

#4 7 years ago

Are the ground modifications/improvements done on the 'bad' SDB?


#5 7 years ago
Quoted from KenH:

Are the ground modifications/improvements done on the 'bad' SDB?

Yes, and on all the other SDBs I'm using to test.

Also, I replaced the .100 header pins as I thought maybe the issues were due to J4 not getting reliable contact. But nothing changed after replacing both J3 and J4.

#6 7 years ago

Bump to see if anyone has any ideas.

#7 7 years ago

All I can see on J3 is pins 14 & 15: +5 to MPU; 18 & 19: ground; 11: +12 to MPU. Pin 7 is marked for future use, so if you have a wire there do a continuity test on it to the S & T and see if it is involved. Also pin 5 is marked as going to power supply and sound module, which was probably on games before the S & T but it might still be involved.

Also make sure the switches are registering as the correct number designation. Incorrect switch reads will obviously result in the wrong sounds being generated.

You do have a Squawk & Talk right, not the earlier SoundsPlus board?

#8 7 years ago

Yes, S&T.

Nothing on SDB J3 Pin 7.

SDB J3 Pin 5 does go to Pin 9 on the S&T. I don't even see this referenced on the schematics for the S&T so I'm guessing it isn't necessary and I could remove it and then test.

#9 7 years ago

Both FG and 8BD connector-to-connector schem sheet still show the Sound Module.

#10 7 years ago

I mean the S&T schematic, my FG manual has the S&T. It does not show 43v coming in on J1 Pin 9 from the SDB or rectifier board. Unless I'm missing it.

Sounds plus schematics show it coming in on Pin 9 but unused.

I'll try lifting it tomorrow and see if anything changes. Can't imagine it would cause any problems but at this point I don't have any better ideas.

#11 7 years ago

Looked at the S&T, J3 Pin 9 is not connected to anything. So I don't see how this SDB can be causing the behavior it is.

I don't give up easy but I'm putting this one on the shelf as I need to fold up the game and move on to other things. If I get a chance I'll try it in another game and see if it misbehaves. Thanks for all the help.

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