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Oberheim Matrix1000 - changed battery, got noise on audio output

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Oberheim Matrix1000 - changed battery, got noise on audio output

Postby hansvonderfuel@gmail.com » Wed Sep 04, 2019 10:59 pm

I just had a professional engineer replace the battery on my Matrix 1000 synth, as patch memory was not working. Patch memory works now, but instead I have gotten a terrible noise on the audio output.

I ordered the replacement battery and battery adapter from:
https://www.ebay.co.uk/itm/163771198138

The engineer took off the existing battery that was soldiered onto the circuitboard, and replaced it with the adapter with new battery inserted.

When the unit is turned off, with power cable and audio and midi cables connected, the noise that I now get on the audio output, is really loud. When I turn the unit on, the noise is reduced to a hum which can be heard if I turn the volume knob on my audio interface up, it’s noticeable when recording sounds from the Matrix1000.

Here’s the thing: If I take the battery adapter, which has wires attached to the + and - pin, and touch the chassis of the Matrix 1000 with the 3rd pin which is not in use, the noise disappears. If I take the battery out of the adapter, and again, touch the chassis with the 3rd pin, the noise does not disappear. The 3rd pin is, according to the engineer, a + pin as swell. If I touch the chassis with the + side of the battery, the noise disappears, and if I touch the chassis with the - side of the battery, the noise disappears. If I leave the battery’s + side attached to the chassis, and screw the metall cover back on, the synth won’t start up. Therefore I conclude that it’s not a good idea to attach the 3rd pin to the chassis. But the fact that doing so, removes the noise, indicates that there must be a solution to get rid of the noise. The engineer is a specialist on equipment for boats and shipping, so he’s not a synth man. Maybe somebody reading this is, and can help me identify a solution.
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Re: Oberheim Matrix1000 - changed battery, got noise on audio output

Postby Hugh Robjohns » Wed Sep 04, 2019 11:08 pm

From your descriptions, I'd hazard a guess that there's a re-assembly error -- an earth connection is missing because of a missing screw securing a PCB to the chassis, perhaps, or a wiring loom or ribbon cable isn't fitted correctly.

H
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Re: Oberheim Matrix1000 - changed battery, got noise on audio output

Postby Arpangel » Sat Sep 07, 2019 6:43 am

Or.....some of these battery adaptors come with two, or three legs, and it's often that only two are needed. It's best to chop the unused one off, otherwise it can get in the way and short things out. Just a thought. I'd take it apart and make sure all connectors are tight etc.
Besides, the engineer should have done a mechanical and audio check before delivery. IMO it's essential when doing any work like this.
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