(Topic ID: 24704)

Data East speaker noise - ideas for a cure


By roc-noc

7 years ago



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You're currently viewing posts by Pinsider viperrwk.
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#15 7 years ago

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

Quoted from XPinPinball:

I have never not played a DE game and not had that hum, regardless of my supply in the game or an original.

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

3 weeks later
#27 6 years ago
Quoted from castlesteve:

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.

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

1 week later
#60 6 years ago
Quoted from minnesota13:

Also, you might try isolating the sound board from the cabinet ground, the opposite of making sure your screws are all in place and tight. The sound board obtains ground from wiring through the connectors so it will operate without being grounded to the cabinet ground. Could be a ground loop problem.
The other thing is, the root cause of a sound problem may differ from machine to machine, location to location so a common fix may not apply to all cases.

I believe this is worthy of further investigation. I notice that if I loosen the mounting screws for the sound board the hum is lessened. Besides, Brett Davis of XPin has said that he has always heard the hum whether an original power supply was installed or one of his. I have one of his in my R&B.

viperrwk

#65 6 years ago
Quoted from Matt_Rasmussen:

Would a switching power supply like that introduce ripple as well? I'm no electronics genius certainly, but I seem to remember that is a negative property of that scheme?

It's not a ripple issue, it's a noise issue related to the frequency of the switching, which can be mitigated by filtering the output and choosing a switching frequency that keeps the noise out of the audio circuit. Lots of AV equipment today use switching power supplies though I'm sure there are the purests who would prefer their AV equipment with a linear supply. Perhaps Brett will comment on what he does to filter the output on his PS.

viperrwk

1 week later
#112 6 years ago

I spoke with my friend about that missing VR1 component on the power supply, he looked at the schematic and figured that particular component was related to sending 12V to the display and not the sound board.
So now I tried another test... I unplugged the sound board CN2 connecter (the one that supplies +12V, -12V, +5V, and ground) and wired in an external power supply from a PC. With the external PC power supply, the game is PERFECTLY quiet! All buzz is gone! All noise related to the light matrix is gone!
So... where does this leave me? It tells me that the sound board is good for sure. The source of the buzz/noise is NOT the sound board. It MUST be the power coming into the sound board that is being fed from the power supply.
Earlier today I ordered all new capacitors for the power supply. I should get them next week. I will follow up with my findings once I replace all power supply caps.
By the way, here is a picture of the broken VR1 component.

So I pull the sound board from my R&B - I have a bad hum in attract mode. I was planning on changing C30 and check the ROMs to make sure they were up to date and discovered my VR1 looks like this:

SSCN4975.JPG

It was an interesting coincidence that Chad had a problem with VR1 on his PS and I had a problem with VR1 on the sound board. My sound works - just have the DE hum.

Also, turns out that only one ROM - U17 - verified correctly against the version on Stern's website which makes me suspect some form of bit rot.

Anyway, need to order a new VR.

viperrwk

#114 6 years ago
Quoted from Crash:

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.

Don't know what happened before I owned the machine. I never noticed this until I pulled the board, which had all original markings and stickers on it making me think it had not been removed since it was installed at the factory. And there's no indication that anyone has taken an iron to it or replaced any components previously.

As an interesting aside, several of the installed caps are uprated voltage-wise over what's on the schematics - specifically C17, C30, C53, C62, and C69. I suspect this was done to streamline manufacturing and reduce the number of different components used on the board.

Anyway, if the VRs are stressed, it wouldn't be a bad idea to replace them as well - they cost less than $.50 each from Ed@GPE.

viperrwk

2 weeks later
#148 6 years ago

Just wanted to post my results as well which confirms this is a ground loop issue.

I had bad crackling/hum in my R&B speakers very noticeable in attract and running diags especially during lamp and flasher tests.

Changed out VR1 & VR2 on the sound board. The crackling was reduced - likely because of my busted VR1, but noise was still there.

Changed all the caps on the sound board - noise was still there.

Don't like nylon screws so instead got nylon washers and put one each on both sides of the sound board at the four mounting screws - 8 total. Speaker noise gone.

The problem now is the buzzing Cherry display. I tried a Vishay I have that is partially gassed and the machine is eerily quiet. Except for the buzzing the Cherry works fine so I'll live with the buzz for now.

I should also mention that I have an XPin PS installed so if you have a different config YMMV.

So for about $.25 and 10 min work you can significantly reduce or even eliminate that speaker hum.

Thanks for all the constructive discussion in this thread.

viperrwk

#151 6 years ago
Quoted from Pimp77:

Every Cherry display I've ever had buzzed horribly. Get rid of it.

Yeah - I should. But I can't hear it during gameplay and when I do hear it in attract, it reminds me to turn the machine off...

viperrwk

1 year later
#158 5 years ago
Quoted from markmon:

The nylon washers on both sides prevent the screws from touching the ground pads on the sound board. Could be verified with a dmm once in place though.

And IIRC there's no through plating on the mounting holes so as long as you isolate both sides you should be fine.

viperrwk

#169 5 years ago

Just to add - been running like this for 15 months and no problem. I still have the buzzing Cherry display that refuses to die though...

viperrwk

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