Bally Fireball Classic Sound

[Koplings]

So I went to fire up my 85 bally fireball classic and there seems to be a problem with the sound. here is what I observe

- game plays fine, just the sound and effects are now really faint
- I can faintly hear the game sounds and effects but the volume is almost zero (some times when I turn the game on it is a bit louder but still faint)
- when I turn on the main power switch I hear what sounds like speaker static noise for a few seconds (PSSSS...)
- as the high scores flash on and off while in attract mode I here a buzzing static sound on and off - if I open the back box door it goes away but as I close the door I hear the noise again (almost like an interference type of sound)
- am using an alltek mpu board and also a new power supply board; the rest of the boards are original

any thoughts where to start would be helpful; i've tried reseating he various connectors but that hasn't helped

 

[Koplings]

Hey I just figured it out (actually I didn't - there was a post on pinside that seemed on point). pasted it here just incase any one else has the same problem. cheers

The first picture is the board in the back box, if not mistaken, the sound board. The black item I pointed at is the second volume control. On mine it occasionally loses contact. So I "cycle" or "sweep" it by turning it up and down a few times. In fact when I was taking these pictures I had to do that to get the sound to come on.

 

[Menace]

Yep, first thing to check & replace is the volume pots on all these old Bally PCB's (not just the sound PCB's). They were cheap back in the day and are usually the first thing to fail.

Glad you got it sorted.

D

 

[sylvain]

Yes, on those sound boards, the volume control is often dirty or spotty.
Usually, a very small amount of safe-for-plastic quality contact cleaner spray such as De-Ox-It, followed by turning gently the control
up/down multiple times afterwards, will restore the potentiometer for many years - without the need to replace the part.

Next common issue for sound problems is cold solder joints at header pins, or on output transistor/amplifier.
And - bad electrolytic caps. I find that an ESR Capacitor tester is very useful here.

Cheers,
- Sylvain.