This video explains the noise you're hearing as "dirty electricity." You can see this at 5:30. You hear the normal 60Hz sine wave but also some static if you listen closely.

Check your boards have all the screws and they are tight. Loose/missing screws will cause this hum. I fixed my hum issue by putting in screws that were infact missing. Like you said it didn't do this hum until you got home with it, so maybe screw got loose or fell out. Always look for the obvious and easy stuff rule them out first!

I have a TFTC and it does not have a hum. So I would argue this is not "normal data east noise". I liked your suggestion of a band-aid: 200hz high pass cap - this should eliminate it from the backbox but not the cabinet. Very cheap and easy to test.

Do you have your wiring for speakers wrapped in ferrite core?

My JP has a bad hum, drives me nuts. I'm a total noob as far as audio and electronics go so I wouldn't have a clue how to fix it. The grounding braid looks to be all good as far as I can tell. But the wiring for the speakers look a bit poor. I could try replacing that wiring.

no issues with my DE LW3 (quietest pin I own in fact), friend has a TFTC with no hum. I would say a part missing, like a ferrite bead (as suggested), or a loose ground somewhere.

Doubting bad speaker, usually when a speaker goes bad though it still functions without noise (might crackle when you adjust the sound pot). My space shuttle did this, replaced the bottom speaker with a new $16 pyle, crackling went away (not surprising for a pin that's almost 30 years old).

What does your hum sound like?

My JP hums in attract mode, and you can hear it as the lights change and whatnot. So does Tommy. And VND does it to an extent too. Start the game, and you can't hear it at all unless the sound is off, and I keep my games quiet.

To me, humming in attract really isn't worth messing with. If that's not it... what is it doing?

Mine hums in attract mode like yours goatdan. I can't notice it when playing only because it's making noises that drown out the humming.

When I owned my LW3, I read a lot of stuff about DE. I came across a post talking about the caps on the sound board could be the culprit. I never had any issues with mine so I didnt really get too into this issue.

My DE:SW does this.

Ill take a look in the head tomorrow.

To bring this up again, could someone point me to the caps in my JP on the soundboard that I would change to try to clear this up?

When I did my Star Trek and Hook, I replaced all the caps on the sound boards, and replaced the speakers. The hum is completely gone on both.

First double check and make sure all your screws on all of your boards are nice and tight. If that doesn't help, replace cap C30 (I think is the correct one) on your sound board. It's a 1000 uf @ 16v. If that cap is going bad it can cause a hum.

The DE hum is a common problem. Here's a quote from Brett Davis/XPin:

So the problem is not the PS - instead it's somewhere on the sound board. Big70 has the cap right to go after first (it's on the +5v feed to the sound board) along with making sure the screws are tight.

viperrwk

It's obviously a filter capacitor with the high level of capacitance and if it's not filtering properly (dried up if it's an electrolytic capacitor) then it will not absorb this noise and pass it through to the audio amp.

I replaced the +5v cap (C30) on my DE:SW and it did not fix the hum. Mine actually also gets worse if the board is tightened down, loosening it reduced the hum to the point where it is a minor annoyance, so I didn't go any further.

Hmmm... I'm also interested to see how people end up cleaning up the sound because my TFTC / JP / LAH all have hum (not as loud as I have heard others though)

Any luck with this guys? I'm going to try to replace the cap this weekend and see what happens.

keep us informed, i have the same problem with my LW.

See my post above. I no longer have any issues with either of my DE's. Not that I can hear.

Same problem with my DE Simpsons. I'll be following this thread as someone may find a cure.

I've solved this many times before.

Your -12v rectifier is bad on the power driver board.

It supplies only the sound board. The sound board will work without it, but it will sound like shit and hum. Easy to test.

I had a horrible hum on my Checkpoint. I replaced C4 (the 18000uF cap) with 4x4700uF caps and the hum is pretty much gone. I have since picked up a TFTC that hums pretty bad. The power supply on my TFTC has the 4x4700uF caps installed so I'll be replacing them with hopes of reducing/eliminating the hum as well.

Castlesteve,

Thanks for the heads up on the rectifier issue. Could you go into a few more details on the test procedure?

I don't have the schematics on hand, but there is a -12v test point on the sound board and or the driver board. It is supplied by a single rectifier and fuse(likely). Other than the caps as suggested above, this is one nobody expects. It's a cheap part and common. It supplies the negative rail for the amp.

You mean on the power supply board? If so, it contradicts Brett Davis' experience and my own with an XPin PS in my R&B that's stupidly loud in attract mode. (See my previous post in this thread.) If it's something else please share! I want the noise to go away!

viperrwk

You should be able to read cap values on the board to replace them. However, sometimes it's recommended to go higher than original for reliability. I know great plains sells cap kits, doesn't look like they sell it for data east (unless I suck at searching), example:
http://www.greatplainselectronics.com/proddetail.asp?prod=BALLY-S51E-KIT

Even if they don't sell the kit, you can search on mouser or digikey for these same parts

Why would a bridge rectifier be problematic? It will put out the same dirty power that is fed into it from the transformer, which in turn gets its dirty power directly from the wall. This noise in general is what line power sounds like. The normal 60Hz hum plus a lot of line noise caused by power lines picking up other sources of radiation, radio frequencies, etc. The key here should be to feed the amplifier with clean DC power, and re-capping the sound board does this by conditioning the pulsed DC power coming from the rectifier.

I believe the suggestion was that the rectifier is bad/dead. In other words there is no -12 being supplied.

I've had a couple of DE that hum...my Hook though, is silent.

I've replaced the suggested caps and tightened screws, added jumper ground wires, etc.

Nothing really fixes it as far as I can tell. Clay says to change the caps, but in my experience that doesn't really work well; maybe a 5% reduction in the hum, which isn't very much.

Someone wrote one that it's a problem with the dirty power out of the transformer, when I emailed him for more info, he didn't respond.

Also, I found someone that had a friend that built a daughter board for the sound board (I think) that fixes the problem. But he won't build any more and wouldn't give me the schematics or any other info so I could do it myself.

So much for this being a small nice "club".

I took the problem to one of the electronic engineers here, and asked him. He thought it was a design issue with driving some of the amps too hard, combined with poor quality (large variations in batches) used and 60 or 120 cycle noise. I put a scope on the line and saw a lot of 60/120 hz noise.

I just sold both games before I figured out a solution.

So a bad regulator might be in the realm of possibilities. As well as a lot of other things that create noise in the circuit.

Robert

castlesteve I don't see any standard-sized rectifiers on the driver board, is this a small wafer-style rectifier? Where is it and what is it labeled as? I can't find anything in the CPU board schematics other than a -12v connection to CN17-8 that doesn't seem to go anywhere. I do, however, see a voltage regulator on the -12v side of the sound board, is this what you meant?

Does replacing the speakers work? I have noticed the website flipper fidelity. What if you replacing with different brand Williams Bally or Stern instead of the Data East show on the website. I am curious to know if it works. Also, let me know if anyone wants to sell their TFTC especially on the west coast which is closer to me as I have been looking for one in great condition with Led's.

http://www.flipperfidelity.com/products.php?cat=Sega/Data%20East%20Speaker%20Systems&itemId=95

http://www.flipperfidelity.com/index.php

Speakers don't hum by themselves, they need an amplified signal.

A broken speaker might distort if it is rubbing, it might not make any sound if the coil is open.

Somebody needs to get an O-scope and trace the hum backwards through the circuit.

I'd probably replace all the caps for all 3 outputs and the power section (assuming you determine it's the sound board). I get all my stuff from digikey. Caps are cheap and easy to de-solder so I figure look at the schematics and start replacing ones that seem to be the most likely culprits. You might want to consider replacing the C4 cap on the power supply as the one on my Checkpoint was beyond dead. Make sure to get the higher temperature caps on the power supply!!

Well, recapped the entire sound board and have a new XPIN power supply and the buzz is still there, and possibly worse. It was the same with the new caps and the old supply, with the new supply it might be a bit worse.

I've tested the grounds and they show continuity from the head to the body etc.

Could it be the display? There is an issue with the display, I'm just curious if that could be inducing the noise in the audio.

Can someone get castlesteve back in here? Can't figure out what he's talking about but he may be on to something.

I thought the same thing and replaced my display. Buzz is still there, although I did have SOME DMD noise that is now gone. The speaker hum is annoyingly there though still.

I really wish we could get to the bottom of this. This seems to be one of the most common complaints for 80's and 90's games. Data East and Williams especially.

Sorry, I totally missed these updates.

The -12v is created by a bridge rectifier on the power supply, not the sound board. However I believe much of the sound problems you all are hearing is probably with a working machine.

So there are other options. In the car audio world, we heard line level noise all the time due to floating grounds and various motors making electrical noise (remember when your mom used to run the vacuum and the tv would go crazy).

This can be solved by using an automotive line level filter. It would have to be modified - or rather - the pinball wiring would have to be modified to plug into it. It's a possibility. Another option would be to further isolate the wires running to the audio board and put ferrite cores on them.

I now have a de that I brought into my personal game room that all of a sudden makes audio noise that didn't in another location. You could also try using a UPS as a cheap AC line conditioner.

I'll try some things and report back

I haven't tried to fix mine yet but I only got it a week ago. Before I start buying parts I think I'll watch this thread for a bit.

Well moving components around in the backbox and adding ferrite cores did not work. So the source of noise is not likely created from their own components or non- shielded data. I'll try next an AC line conditioner and see if the noise is making it in that way. I doubt it though as transformers act as a line conditioner by themselves.

Next ill search for AC ripple on the amp rails. It better be clean

Go to your breaker box and start shutting off power to various appliances in your home. I betcha the source of your hum goes away.

Transformers act as low pass filters, but they aren't complete line filters. Especially considering the primary and secondary grounds are tied together physically, so high freq hum will come through the ground.

update...

Ok, so I have a high end AC line conditioner and I tested before and after and made measurements as well.

Without: measured from the TPs on the power supply, I was getting 300mV of AC ripple on the +12V output. About 50mV of ripple or less on the +5v and -12v outputs. So that's pretty low.

With the AC line conditioner, it measures the same. So we can rule out noise introduced from outside.

So, now we need to look at quieting down the output of DB1 (CM3501) on the power supply. It has a bank of capacitors C11 - C14 used to smooth out the output of the bridge rectifier. BTW, this is also the same rectifier that creates -12V... and I've seen where half of this rectifier fails before - which was my original post response.

The output of this rectifier is labeled un-regulated +12V. I measured it around 11.05V which is fine. It's called un-regulated because it still has noise on the line and the other circuits that use it are responsible for regulating and smoothing the input. So we can look at either the sound board to smooth out this voltage or smooth it out right at the power supply.

Again, this may not solve the problem, but my next guess. I have a bench power supply that hopefully can supply enough voltage and i'll drop that into the circuit to see if that cleans up the hum. If so, then we can just add the right capacitors to the power supply and if necessary make an inline connector for people to drop in to fix the hum. That's the aim anyway

Just for shits and grins, temporary lift the ground on the primary of your transformer. Not a permanent solution, but a test.

If that were the case, wouldn't my williams machine buzz too?

Not necessarily.....Lots of factors go into audio buzz. Obviously disconnecting breakers or lifting the ground aren't solutions. Trying to identify the source.

Do you think this noise is coming in at the amp or is it mixed in with the line-level signal before it's amplified?

Personally, I think it's noisy power, but trying to track that down.