(Topic ID: 24704)

Data East speaker noise - ideas for a cure

By roc-noc

7 years ago

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  • 507 posts
  • 136 Pinsiders participating
  • Latest reply 4 days ago by jimgravina
  • Topic is favorited by 129 Pinsiders


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#2 7 years ago

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.

3 weeks later
#16 7 years ago

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.

3 weeks later
#29 6 years ago

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.

#32 6 years ago

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?

1 week later
#38 6 years ago

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

#49 6 years ago

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?

#61 6 years ago

So we might actually be looking at 2 different issues here. I call TYFSBASI: Take Your Effen' Sound Boards and Shove It!

#66 6 years ago

Someone just posted this, claims a new DMD solved his problem. But it's a Williams game, not Data East.


#92 6 years ago

Chad can you get a picture of that area? Either it has somehow broken off or it was never stuffed from the factory (most likely the latter). If this is that case that might explain your problem, according to castlesteve, who says missing +12v would cause it.

#94 6 years ago

Wow! So that means the X-Pin power supply isn't providing a clean voltage source either. Might want to check that out Brett and do some testing. Our Data East supplies and dropping like flies and we're down to just one working original. Would be really nice to have no hum when we order replacements!

You need to look at that 12v wave on the scope. I'm sure it's a mess.

#100 6 years ago

Just for kicks I need to listen to Hook really close as it has a replacement X-Pin power supply. I'll report back what I find.

#105 6 years ago

True, but I keep the boards grounded and include all the screws. The hum is still there on Hook.

#108 6 years ago

I thought a ground loop was caused by components having different ground potentials and instead of that current discharging through a ground source it dirtied up the normal circuit lines and caused problems. But you guys have a point.

#113 6 years ago

Did that regulator fail under stress or did you drop something on the board? Other people with this issue should check this component on their sound boards to see if it has failed like this.

Back to the ground loop issue though, I'm starting to "get it" now. Basically this means the sound board has more than one path to ground which completes a circuit and it's picking up noise from the other boards? Where would the second path to ground be besides the ground plate? Found a couple of videos if others are having trouble understanding:

#116 6 years ago
Quoted from robertmee:

The paths to ground are likely numerous. You have the ground plate as mentioned. You also have interconnects that carry grounds between boards where other boards are grounded. You also have the main power distribution which is grounded to your wall outlet and the ground braid in the game.

The ground plate isn't connected to the ground braid? So really what needs to be done is remove all connections to ground but one (the ground braid) and that should solve it?

#118 6 years ago
Quoted from robertmee:

Both these boards have their own ground via the mounting screws...the ground interconnect between the two (probably the common of a DC voltage), supplies a potential ground loop. That's why when a clean PC supply was installed in one test, the hum went away...you no longer had the ground interconnect between power board and audio board.

I think THIS is definitely the problem. The solution though isn't exactly ideal... eliminating the path to ground through the common DC supply by adding a second power supply for the sound board.

1 week later
#122 6 years ago

Plus, disconnect the lamp matrix columns and rows from the driver board and see if anything changes. Could the strobing of the lamp matrix be generating the noise? I've listened carefully to various Data East games in attract mode and the noise seems to vary in volume depending on how many lamps are on. Plus, consider the fact that incandescent lamps draw more than 10 times more current than LEDs.

Do you have polarized/non polarized LEDs you can test with?

#134 6 years ago
Quoted from ChadH:

Hmmm... so now I am concerned. But those posts are from one year ago. I would think that those issues would have been resolved. Or should I still be concerned? Anyone know what exactly to check on the board to see if it has been improved?

Rottendog unfortunately isn't fixing the problems. Check your high voltage levels with a meter. I had a friend who installed a Rottendog power supply that caused fuses to blow and a burning smell. Even if your voltages are ok now the regulators will eventually fail since they are driven so much out of spec. I would recommend replacing the Rottendog with an X-Pin. Much better design.

#138 6 years ago
Quoted from ChadH:

Dang. I checked and everyone is out of the X-Pin XP-DE5047 power supply.
So, the regulators on the Rottendog that are out of spec... wouldn't it be possible for me to swap those out with ones in spec? Has anyone offered up a solution? I'm good with a soldering iron but would just need to know what to do.

PinScores are virtually identical to X-Pin stuff, both brands are owned by Brett Davis. X-Pin just expands the selection of boards available and improves upon the already excellent design of the PinScore boards.

1 year later
#156 5 years ago

I have this issue pretty bad on a Jurassic Park, I think it's the worst of any Data East game I've ever heard. We will try floating the sound board with nylon washers. But wouldn't you also need nylon screws since metal screws will still maintain a path to ground?

#159 5 years ago

Wow whattya know!! Floating the sound board eliminated 100% of the noise! So even though floating the sound board doesn't work for some, it's the most sure fire way to solve this age-old problem.

Next I will have to verify the game is grounded. I want to get as much info on this specific machine (Jurassic Park) as possible. Any questions in particular you guys would like to ask about the boards etc. to increase the chances of success in the case doing this doesn't work for you?

#160 5 years ago

Just tried the same thing on a Lethal Weapon 3, noise is completely gone.

#166 5 years ago

Chad I was reading some of vid1900's posts in that Fire thread. He says if a component fails, shorts out, a cap dries up etc. that could change the intended path to ground, and the resulting difference in voltage/potential between boards would create a current in the ground line. But wouldn't this only be an issue on old (15+ year old) machines? I read some people talking about this also being a problem when the games were brand new in the early 90s, so evidently there was some other problem besides aging/failing components. We have previously established why we are seeing this issue (ground loops due to poor sound board design) but what exactly constitutes this "bad design" and why aren't all machines affected then?

Couldn't your theoretically install a diode on each board's ground connection to allow a connection to ground as well as preventing unwanted current from coming from the ground plane into said boards?

10 months later
#188 4 years ago

I made a very interesting discovery today... if your Data East/Sega jumbo DMD game has loud speaker noise (as in on par in volume with actual game sounds) check the part number of the sound board. I'm working on a Baywatch project that has a brand new X-Pin aftermarket power supply and perfectly working sound board that was recently repaired by Clive at Coin-Op Cauldron. The noise coming off that thing was terrible, and lifting the sound board's ground did absolutely nothing. The board was originally in a Sega Frankenstein, so on a whim we had the idea to swap them both back and see what happened.

THE NOISE WAS COMPLETELY GONE! With the sound board's ground lifted literally the only thing I heard was faint mains hum from the main transformer, and this was in a perfectly quiet room. So perhaps between games/sound board revisions the design has changed in such a way that ground loops can proliferate through the system if the board is installed in the wrong game. If you have a noise issue look up the board's part number in the manual for your game and see if it matches.

Now in my case, the Baywatch machine cleared up 100%. However, the Frankenstein machine the board was originally in (which was repaired with a few caps replaced in the process) did not clear up once we re-installed its board. Frankie also has an X-Pin power board. But that discovery alone I imagine could certainly help a lot of people banging their heads against the wall trying everything under the sun to get rid of the noise. Parts got swapped all the time when these games were on location. Give that one a shot and report back!

1 year later
#243 2 years ago

The new speakers may just be more accurate and bring out that low 60Hz tone more effectively.

7 months later
#322 2 years ago

Can you get a video of the sound?

1 month later
#335 2 years ago

Not to mention the extra load could increase ripple in the supply causing hum.

5 months later
#372 1 year ago

Wow, incredible find! Can we mark ruckster's post a key post?

3 weeks later
#396 1 year ago

I have used the free version of SpectrumView for iOS with good results.

#398 1 year ago

Here's a hint: it looks and sounds exactly like dirty electricity. So probably some high frequency transient voltages that sound like the rectified 120Hz signal coming off of the main 12v rectifier.

#401 1 year ago
Quoted from altan:

Thanks for sharing crash
I did a quick test and it confirmed by thought, but added more. I eded up using Visual Audio as the other program didn't allow a more specific enough view of the frequency. Also, VA seems to do FFT transform and specifically told me my biggest points were
119.8 Hz (@ 41dB) and
839.8 Hz (@ 57dB)
And ... ~840 Hz is a harmonic of 120 Hz so I think this is a strong sign...

Ok, let's follow the dirty electricity suspect. Do you have an EMI filter you can plug in to the same circuit to see if it has any reduction on the hum? Generally it's a white box that plugs directly into the wall.

1 year later
#481 80 days ago

Our Baywatch machine was pretty noisy when idle. After replacing all capacitors on the power supply, the hum is virtually gone. You have to get really close to the speaker in a quiet room to hear the hum now. In this case, this is a power supply that came out of a Sega Sports redemption game and appeared to have the all orignal capacitors. The difference is astounding! Listen, this is with the mic very close to the speakers.


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