(Topic ID: 24704)

Data East speaker noise - ideas for a cure

By roc-noc

7 years ago

Topic Stats

  • 507 posts
  • 136 Pinsiders participating
  • Latest reply 6 days ago by jimgravina
  • Topic is favorited by 129 Pinsiders


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#35 6 years ago
Quoted from Jackontherocks:

Does replacing the speakers work?

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.

2 weeks later
#73 6 years ago
Quoted from ChadH:

C31 (470uf) is 50 volt and C52 (470uf) is 35 volt. Should these voltage specs be maintained when replacing them with 1000uf?

You can always use higher voltage Caps than the original specs, if they physically fit on the board.

Newer caps are often smaller than their 20 year old cousins, so this is probably not a problem.

#74 6 years ago
Quoted from XPinPinball:

Hopefully not to wordy...we engineers tend to drag things out ;}

Not wordy at all, great job.

#104 6 years ago
Quoted from Crash:

So that means the X-Pin power supply isn't providing a clean voltage source either.

Not necessarily.

If you have a ground loop, no matter how clean the power, you will have hum.

There could be a broken board trace, a cap (new or old) with high resistance, or any other shorted component that could be creating the loop.

Even worse, another board in the game could be supplying the easier path to ground, so it might not be the sound board itself; but the sound board + the power supply completes a different path to ground.

#107 6 years ago
Quoted from Crash:

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

A ground loop is where one part of the circuit finds a "short cut" or different path to ground.

#109 6 years ago

A few years ago I was playing a Russian mobster in a movie and there was a giant ground loop getting into both the audio feed (boom mic) and into the video (rolling bars).

We were loosing light, and although it's normal for lead actors to come back to overdub their lines, it is normally never done for a one line speaking part, as I had.

Everyone was in a panic so I stepped out of line and suggested to start unplugging things until we lost the ground loop.

It turns out it was the DAT (Digital Audio Tape) recorder for the boom; a very necessary part of the production.

We used a "cheater plug" on the DAT power cord that took a 3 prong grounded and turned it into a 2 prong ungrounded plug. This broke the ground loop and we finished the shot.

Now the same generator, lights, DAT, mixer and camera set up had been used together 100 times before, but on this occasion the DAT deck was somehow finding another path to ground and mucking up everything.


Another time a friend had installed a zillion dollar home theater set up and had a 5 channel dedicated amp to run 5 speakers. About a month into using it, just the front left speaker started humming loudly with 60hz hum.

He was blaming the amp manufacturer and swearing up a storm.

After swapping inputs I found that it would only hum when all 5 inputs were in use. Unplugging any of them killed the hum in the left speaker.

Lifting the Comcast feed cable from the rack instantly removed the hum, so we used an isolation transformer between Comcast and the rest of the equipment and all was well.

Somehow in the last month, Comcast had given itself a different ground potential and the symptoms showed themselves in just one channel of the amp.

Strange stuff these ground loops...

1 week later
#121 6 years ago
Quoted from Pondwater:

So I wonder since these bulbs are located between the speakers, could they cause interference when powered? Or could the low draw of LEDs fix this issue or did I do something else by accident?

Could be an accident, or the diode of the LED blocked the leaking current.

Swap the bulbs back (I know it's a hassle) and let us all know!

#140 6 years ago
Quoted from Crash:

PinScores are virtually identical to X-Pin stuff, both brands are owned by Brett Davis.


Brett is being sued by Marco (they own Pinscore) when he started Xpin.


#142 6 years ago

The don't all have hum. I play GNR all the time and it does not have a loud hum.

Some games hum of any brand (especially sys11 Williams), but if it bugs you, you hunt it down and fix it. It's not the same fix on every game, even two different games of the same title.

1 year later
#171 5 years ago
Quoted from Crash:

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.

Just plain ol' bad design.

This stuff was commercial equipment. If it hummed in a bar or bowling ally, who cared?

Caps back then were often 20% tolerance, so what worked in the design lab, might be totally different in the real world with a different batch/brand of capacitors.

Even today, audio components are produced (especially tube equipment) that need internal modification to be truly quiet. Iffy grounding schemes that don't play nicely with other brands of gear.

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