(Topic ID: 24704)

Data East speaker noise - ideas for a cure


By roc-noc

7 years ago



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#1 7 years ago

I just picked up a nice TFTC from the Chicago CL last week. I didn't notice the speaker hum until I brought it home.

After searching for a cure, this sounds like a common DataEast problem but without a clear solution.

I have some ideas but wondered if any others have found a cure. First, everything is well grounded. There could be a ground loop but I haven't had time to figure that out yet. The machine is pretty clean and mostly original except it has a newly replaced rotten dog CPU board. Unfortunately, I didn't get the original CPU board.

1) The noise is mostly coming from the speakers in the head. And it sounds like 60 cycle hum. Has anybody tried using a passive high pass filter on the head speakers? Or else a passive crossover between the head speakers and the cabinet speaker?

2) Some say that just replacing the speakers with higher quality units will reduce the noise. I'd rather solve the noise problem first before putting money into new speakers.

3) Others have said that the DE pre-amps are designed way too hot and creating the noise. Anybody figured out which resistors to change to adjust this? And does it work?

Thanks, Tom

#3 7 years ago

I don't have this problem with any of my other pins and my noise is more 60 cycle hum than that. So are you saying its a power supply problem? Bad caps? Do you have any experience with this or just guessing?

1 month later
#33 6 years ago

I only have one bad channel making the noise in the top box. I swapped the two speakers and it stays with the channel on the PCB. So I suspect bad caps. But I have not had time to source the parts. It would be nice if someone sold a cap kit using high end caps for this DE board.

Also I have a DE Simpsons coming next week. I figure it has the same sound board so that should make it easier to troubleshoot.

Tom

4 weeks later
#146 6 years ago

As the OP on this thread I have been busy fighting other problems. I did get a chance to replace all the electrolytic caps on the audio board and it didn't make any difference. I also floated the audio board and still have all the noise.

Unfortunately my TFTC came with a rottendog CPU. The lady that I bought it from paid some fly by night Chicago area pin service guy to come out and freshen it up before she sold it. The batteries had leaked so he sold her the new CPU board and of course he took the original, and left all the noise and a few other problems.

I'll try floating the CPU board. Just wish I had another DE machine from the same era around to swap boards to help troubleshoot.

I do have a DE Simpsons in house right now but the audio board is different.

8 months later
#153 6 years ago

Simple test. Turn off the pin. Unplug the DMD power and data cables. Turn it back on and see if it goes away.

2 years later
#210 3 years ago

BTW I did fix my mine. It turned out to be a connector related to the original battery leakage. After I purchased the pin, I ripped out the Rottendog board and bought an original DE board to replace it but saw no improvement. Over the next year, I built up a collection of original DE boards. Tried replacing them all but nothing seemed to work and remove the hum. I even tested different revision boards.

The only thing left was the wire harness and ground system. I thought that maybe there was a bad connection in a molex connector that had been polluted by the original battery leakage problem that the Chicago tech had "fixed" with the Rottendog board.

So I cut out and replaced the two molex connectors that would have been dripped on by battery leakage. Once I did that and screwed the boards down again with metal screws and no ground lift, the hum went away. Only took me about two years of trial and error to figure this out.

That was my fix to remove audio hum.

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