Arp Omni- No Sound

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Arp Omni- No Sound

Postby eddy66t6 » Tue Sep 03, 2013 4:13 pm

Hey guys... IM having a problem getting an old arp omni to make sound, it turns on and lights up, theres a bit of a hiss when you strike a key... but no discernible sound
Any suggestions greatly recieved
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Re: Arp Omni- No Sound

Postby garranimal » Tue Sep 03, 2013 5:00 pm

You haven't said what you have tried yet so first make absolutely sure it's not user error: voice levels are turned up, attack turned down, instrument switches pushed in, etc. However, the Omni is notorious for reliability issues. If no experience troubleshooting electronics, the Omni isn't a good place to start. But if you have the courage and some electronics experience it seems to me the keying circuits and output VCAs are doing their job. The voicing cards may be the culprit not producing a signal. Or perhaps the effects section. Definitely check the power supply to see it is outputting the right voltages. I've had old synths with connector contacts becoming oxidized and requiring cleaning. I always say there's no shame in taking the synth to a reputable tech.
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Re: Arp Omni- No Sound

Postby atkbg » Tue Sep 03, 2013 5:38 pm

Like what was mentioned.

You should also try the individual outputs of each section (ie: bass, synth, strings)
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Re: Arp Omni- No Sound

Postby perfectdefect » Tue Sep 03, 2013 6:17 pm

This is not an uncommon thing. Omni's are full of components that fail readily -capacitors and IC's mostly. There was this recent thread about troubleshooting an Omni: viewtopic.php?f=1&t=72273

A power up with complete failure to make sound may actually be a good sign -it's a component far enough upstream that replacing it may bring everything back to life. There are a few historical examples of people being this lucky.
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Re: Arp Omni- No Sound

Postby sam » Tue Sep 03, 2013 7:14 pm

First stop is the power supply board....You should have +15v and -15v ...Tantalum caps blown maybe.
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Re: Arp Omni- No Sound

Postby Hiwatt » Sun Sep 08, 2013 7:30 am

As sam suggests first test the power supply while disconnected from the other boards. When the ps works reconnect it to the rest of the boards and check for +-15 on each board. If any voltage goes out of spec then the tantalum bypass capacitors on the respective boards have gone bad.
If you get good voltages on all the boards and still no sound check the top octave divider. Is there a good clock signal going in and are the divider outputs active?
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Re: Arp Omni- No Sound

Postby synthparts » Mon Sep 09, 2013 12:59 pm

It's a time-consuming job but all Omnis should have all there tantalum caps replaced (there's close to 100 of them in there :shock: )... You can replace them with common electrolytics...
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