This is the only solution so far that has produced favorable results. Not floating the sound board, not replacing caps, not disconnecting braided grounds on speakers. Running the sound board off a separate supply reduces noise dramatically. I assume this is mostly because of the replacement supply has a much cleaner regulated DC power, as well as eliminating ground loop. I used an open frame Artesyn supply. It's 40W and has no fan, we used it in some of our older pro audio products.

I just have to mount it permanently, I'll try to get pics once it's done.

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Measuring with a sound level meter, the ambient background noise is around 56db, about the level of falling rain, after installing a dedicated sound board power supply, around 25db, about the level of a whisper. The change of -20db is around a factor of 10. In the video below, you can hear the noise with the game's original supply, then you will hear the train whistle sound effect as I attach the dedicated supply, and the resulting quieted noise.

The Artesyn power supply, mounted to the right side of the backbox near the sound board. It is mounted with 1" screws and 1/4" nylon standoffs. The incoming AC power is wired to the switched side of the AC power switch. The connectors are Molex with Trifurcon pins for reliability.

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That's sweet. Now, where do I get one of those power bricks?

Looks like Newark carries them. We have bought many from Arrow distributing. Any model 40W or greater with +5, +12, and -12 outputs will work. The exact model I am using is a discontinued model scrapped from old product, but there are new versions out there.
http://www.newark.com/artesyn-embedded-technologies/lpt43/ac-dc-open-frame-power-supply/dp/23M6705?mckv=oX4uSj7Z&gross_price=true&CATCI=pla-148797591141&CAAGID=20376568461&CMP=KNC-GUSA-GEN-SHOPPING-23M6705&CAGPSPN=pla&gclid=CLfImZ7ymtMCFYNKXgod4CQC9A&DM_PersistentCookieCreated=true&CAWELAID=120185550002950529

Thanks!!!

Very interesting. Thanks !

My Tommy has a pretty loud hum. I might give this a go.

I did the exact same mod on my Laser War in it fixed it . I cannot believe how much better the music and call outs sound without the Data East hum Thanks for the info

Kinda a newb at this. How do you wire that in? Mainly confused about the input side (are you joining after the power switch of the pinball?). A little sketch of the wiring would be a real help to us less knowledgeable guys. Thanks in advance.

Yes, you want to join after the power switch no matter what pin you are wiring up with. This goes for any accessory, mod, or powered subwoofer so that the device comes on when the master power switch is turned on. What you are looking for is the transformer primary side wire pair (usually a black and white wire colored pair) that runs from the power switch to the main transformer. In most games, the mains switch is in a metal enclosure. I prefer to make the tap connections within the box if present. Cut the wires cleanly about 4" away to give yourself some room, strip and connect all three black and all three white with wire nuts (diagram shows just black wire connection, do the same also for the white) PLEASE MAKE SURE YOUR GAME IS UNPLUGGED for safety before you tap into power, regardless if you believe the mains switch is off.

Notice also, according to the schematics for Maverick, the bill validator connection is also a viable option if not using a bill validator. To use it, all you would need is build a proper connector for your accessory.

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Thanks a lot. I will be trying this soon. I totally get it now.

At the risk of sounding stupid(er), how about the wiring from the power supply to the sound board?

No problem. I'm not going to include the power supply side, because that could vary with the model you install. A datasheet should be included with it. For the sound board side you'll need 4 connections. I know it is the same for Maverick and Guns n Roses. Double check your own schematics for other DE games. I advise to be consistent with wire colors that are fairly standard for audio power, if possible. black=ground, red= +5VDC, orange= +12VDC and grey= -12VDC

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Thanks again. I'm going to give it a try soon.

I found an auliliary power supply in one machine I own that is wired to a custom topper. Do you think it would have enough juice to power the sound too? I'll get a pic when I get home...

Yeah, hard to say without knowing what specs the supply it is or what the custom topper is comprised of. The whole point of the auxillary supply I used is that it is clean regulated power for audio and it is isolated from everything else.

Just installed a 40w dedicated power supply today. Works perfect in my tftc! No more hum! As quiet as a mouse!

Where did you get your power supply and what one did you use?

Grabbed one off eBay just search for 40w open frame power supply. Make sure it has outputs +5v, +12v, -12v. Then make your own 6 terminal harness to connect to your sound board from your new aux power and a 3 terminal plug from your main power switch under the cabinet and neutral as stated earlier in this thread. There is currently some for $15 shipped to your door in the US! That's the one I got works great.

Just ordered one . Should get here before next weekend. So I know what I will be doing next weekend.

Same here got the ones for $15. Will give it a try next weekend. Hopefully clears up the hum that is louder than the game.

Just installed the $15 ebay supply in my Torpedo Alley.

Thought I blew the boards up when nothing happened after the ding, but turns out it was just the sound of silence with no hum.

Game sounds amazing now, what a great fix!

Ahh, those precious moments

What size are those Molex connectors? 0.156, 0.1, or 0,093? I believe the original IDC on the soundboard is .0156. Did you use 22 ga. wire?

Molex are 0.156, same pin spacing as the original IDCs. 18AWG wire.

Any chance you could post the link on eBay of the 15.00 version?

Probably this one:
ebay.com link: XP Power ECM40UT31 AC DC Open Frame triple output 40W 5V 12V 12V

But I can't vouch for that company, and seller does not offer returns.

Thank you.

You should still be protected by the ebay/paypal policy if the product is defective.

I want to do this to my LAH.

Could anybody post the wiring diagram needed to convert to this solution?

Thanks!

The wiring will vary according to the diagram print for the power supply. Same thing with your sound board. The soundboard will Have the voltages printed on the board next to the pin layout as posted earlier in this thread. Just match them up. Here's mine it may look different than yours however.

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Thanks! Where did you get the main power from? (main power to this new board)

Please read earlier in this post I have already given that information.

Thank you for that info. I ordered one for my playboy 35th. Can't wait to end the hummmmmmmmmmmmm!!!

Sorry this is probable a little off topic but how can you tell the speaker hum from the DMD buzz? I guess I can disconnect the speakers. Is there anything that can be done to reduce the buzz from the DMD?

Usually you can figure out where the buzz is coming from, disconnect speakers, swap DMD with one from another game, watch the display when it lights a lot of pixels if the amplitude rises.
Unfortunately, there is no fix except for replacement. Some will buzz for years before dying.

You can always upgrade to a color LCD I have no buzz at all with mine

I've been waiting for JP forever, will buy one the day they announce it.

Thanks for the info guys

Unhooked my speakers last night and blissful silence, I thought for sure that insane buzz had to be the DMD. Ordered the power supply last night, thanks for the info.

I ordered my power supply last night, too! Really pumped to get rid of this buzz/hum once and for all. Thanks all for contributing the information.

I ordered one two days ago. It will take 10+ days to come to New Zealand.

You can, but you are now introducing the possibility of unwanted noise in your audio system. The point is to isolate the audio from all other power draws in your machine. Isolation is the only way to dampen the hum.

My only concern is that folks who are buying all these different brands of supplies are doing enough research on the products they are buying. The open frame Artesyn model I recommended is used worldwide in our audio products for radio, where reliability is of utmost concern. They are designed to power high quality audio products. They are also used in very small rackmount chassis without fans, so I know they have plenty of space to vent in a pin. I know some want to save a couple of ten dollar bills, but when someone sticks a closed plastic box, manufactured from someone I don't know or know the design specs, they are completely taking ownership of all the risk, so don't complain to me if you have a problem. Good supplies are not that expensive.

We are all "pioneers". Good luck exploring this option and let us know how it goes.

My Lethal Weapon 3 had such a loud hum you could barely hear the game sounds. I put in a separate power supply this weekend and now there is no hum at all. Wow did it make a difference. I used the $15 one from ebay. Too bad the seller doesn't have any more. Does anyone know where to get any more at that price?

Have 3 other Data East machines to do you.

Is the speaker hum due to age or have DE games always had a hum?

Just hooked up the new power supply what a difference best 15 bucks I ever spent on a pin. Thanks guys

I would venture to guess that it is more of a design flaw, that the noise is there to begin with, but is likely more noticeable as the games age and components drift out of tolerance. In our pro audio products, digital grounds and analog grounds have very specific rules on how boards are laid out, the traces and grounds have very specific separation distances to prevent noise. Noise within the range of audible frequencies is getting in early in the chain and being amplified along with what is desired. I don't think it was a priority to design a high quality audio system in a pinball machine, perhaps it was a method of cost savings. I can't be certain, just my opinion.

Just installed one in my Star Wars......sweet-Surprise.

So I wanted to do it right and instead of using wire nuts, I decided to solder it onto the actual switch.....big mistake. Old wires came off well, it they don't even appear to be copper, or they are crazy oxidized. Even cut them a bit shorter same thing. The wire strings feel like flower wire. No solder sticks to them....anybody any idea?
I am ready to solder new wire onto the switch lug and crimp the rest at this point.
Also, if anybody has a good recommendation for an affordable molex crimping tool? I bought a cheap one from frys and it is pretty much useless. To wide to fit over the crimping portion only.