Speakers whine when I hook up the lights.

Finch

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So I finally got around to reinstalling the lights in my Midway cocktail cab, and when I turn it on the speakers whine. if I unplug any of the 3 sets of lights it stops.

The lights are 3 sets of 2 bulbs for the two control panels and coindoor 24cent windows, they are just wired directly to the switching PSU on the 12v line.

I figure my PSU is plenty strong enough to handle these, but what causes the whine? could it be that something isn't grounded properly? The earth ground for my coindoor isn't hooked up at the moment because nothing is hooked up on the coin door except the lights. The other two sets of lights are attached to the control panels, which are grounded to earth ground.

They are regular incandescent bulbs, so unless something is really weird it doesn't matter which lead is 12v and which is ground so that shouldn't be an issue. The lights work perfectly.
 
Sounds like your 12V line may not be strong enough. Using a Meter, what do you measure your on your 12V line when everything is on?

You've got power to spare on the 5V line so you could use that with the appropriate bulbs.
 
Cut the wire where they're connected to the 12 volts on the power supply, and connect it to the -5. (negative). Then swap the bulbs out and you won't have to worry about it anymore.
 
Ok, sort of fixed it. I checked all my grounds and nothing was wrong, but If I turn the volume up on the PCB (Galaga Pacman Reunion) and then turn it down a bit to the right level using the cabinet's volume pot it's gone.

Seems I originally had the volume on the PCB just a hair above being turned all the way down and that was already plenty loud so I left it, but now it's at about halfway and sounds great. I think the speakers in the cab are meant for a lower signal as they were plenty loud even with the PCB volume way down. I think maybe the whine was just general interference or something from the lights.

Could a standard Arcade PSU really not have enough juice to light 6 little bulbs? I'll check the voltage when I get home.
 
Well the volume trick sort of fixed it, but with the lights on I read 11v on the 12v line, that's a bit of a dip.

I tried hooking them to the -5v line...but then they are pathetically dim. Can you get little wedge bulbs that work fine on 5v? I looked and 3w 12v bulbs were the lowest I could find.

These are in a midway cocktail cab, so there are 6 of them and they were originally connected to this giant brick of a transformer that fed into the linear PSU. I switched to a modern switching PSU and ditched the transformer, so I don't really have another place to plug them in.

I guess I could go all out and switch to 5v super bright LEDs, but it seems silly.

Any suggestions?
 
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