Solved Daytona USA volume very loud

[channel27]

Hi all,

The sound on my Daytona USA is very loud even when it’s turned right down. Not as loud as it is when it’s turned up to max (that shakes the walls!) but still loud.

I’ve swapped the volume pot out for a new one that’s definitely reading 5K.

There’s also a “ADJ V” pot on the amp which I’ve tried adjusting but I’m not sure it’s making any difference.

Anything obvious I’m missing?

When it’s turned right down should it be silent like my other machines?

Many thanks,
Rob

 

[Lurch666]

Are you sure it's supposed to be 5K?
I presume a higher value pot would sort the problem.

 

[channel27]

It’s in the manual as: -
Potentiometer 4k7 carbon LIN
So 5K is already over-spec?

I guess a dodgy amp could cause this?
I’ve got a few spares but I’ll need dismantle a lot to swap it out

 

[channel27]

Well the slave side is now wired for sound and that turns down completely when its volume pot is turned…

It looks like I’m going to have to swap the amp out. It’d have to be the board that’s deepest into the machine wouldn’t it!!

 

[TheDaddy]

Will be repairable mate , poss it just wants an overhall.

Dave.

 

[channel27]

Yeah, I think I’ve got a couple of spares I can try first but if they’re knackered too I’ll take a look at it.

There’s so many things left on the rebuild list I’m looking for easy kills! 😃

 

[ArcadePCB]

How is that pot wired in the amp circuit? The usual way as a voltage divider (input: top end, output: wiper, ground in/out: base end)? If so, check the ground connection to the pot (or check if the ground connection inside the pot is broken). If it is broken, the pot behaves as a variable series resistor instead which could explain the behaviour you've described.

 

[channel27]

I’ve got to the bottom of this and it’s now fixed.

Short story: I’ve swapped out the mixer

Long story: -
Having ruled out the potentiometer itself (by swapping the connector over at the coin door controls so that the potentiometer that controlled the working slave side volume controlled the master), I tried a swapping out the amp. The problem persisted so I tried another amp. Still no joy. I then checked that the voltage going in to the amp was correct as the amp and mixer run off two different AC voltages. Maybe I got them swapped around? Having checked the schematic, all was as it should be re voltages but whist looking at the diagram I noticed that the wires from the volume control actually connect to the mixer board (which passes it through to the amp). On closer inspection of the mixer, some of the resisters around the volume control connector looked a bit corroded. Swapping out the mixer for a new board fixed the issue.

Hallelujah.

Why didn’t I check the schematic earlier! I just assumed that the volume control went to the amp directly.

I’ll fix the faulty mixer board in due course but I’m glad I can now turn the master side down to a reasonable level. Midnight Daytona sessions will no longer wake the neighbours 👍

So if anyone’s Daytona won’t turn down, check the mixer board.