MK6 sound problem

[Don Indallas]

I have an MK6 machine in a MAV500 cabinet.  Every time the lights on the button panel flash on, a thumping noise comes out of the speakers.  The thumping is independent of the machine volume setting.  In addition, when playing music during minor wins, the overall machine volume will drift up and down.  I have replaced the IO board, the logic board, and even the audio amp board with no effect.  I have checked the wiring from the sound for pinches or bare wires.  I really hit the brick wall on this problem.  Any ideas or suggestions?

[Paul]

Check the output of the power supply.
It could be power fluctuations causing
the amp to make the thumping sounds.

[Don Indallas]

Thanks for the reply.  When I listed the things changed out, I totally forgot to mention that I exchanged the power supply.  My bad on that.  You are right, the power supply would have been the first culprit.   The other thing I didn't mention, and I think it has nothing to do with the sound problem, is that I did a ram clear.  I reset the machine from a 2 cent to a 1 cent, and changed the values of the bet buttons.  I'm  stumped!

[jonm287]

Those Mk6 games are strange.  Have you tried unplugging the 2 ballasts for the belly panel lights?  I know it sounds unrelated, but have given me button issues with making them light up when they shouldn't be. 


It's a long shot, but worth a try!

[Don Indallas]

Thanks for the response.  I did unplug the two ballasts, but unfortunately it had no effect on the sound.  I'm open to any ideas, I would flap my arms and cluck like a chicken if it would fix the problem.  These are strange machines, and the conventional fixes haven't worked.

[Don Indallas]

There is a toggle switch on the audio board, which I used to lower the thumping noise down to not being able to hear it.  Then went into the game menu and raised the operator settable sound to a normal level.  The problem is gone!  I don't know what the original function of that togg,e switch was.  Can anybody tell me?