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 Forum index » DIY Hardware and Software
Old, dead Oberheim Cyclone
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Norman Phay



Joined: Jun 29, 2007
Posts: 173
Location: North-East England
Audio files: 1

PostPosted: Fri Jan 01, 2010 3:44 pm    Post subject: Old, dead Oberheim Cyclone
Subject description: Has anyone ever resurrected one of these?
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I was clearing out some lumber in the music room, and happened across my old Ob Cyclone arpeggiator, a piece which I'd forgotten I ever owned.

My memory of it is that I accidentally plugged in a Boss power supply (centre -ve) which killed it, it was expecting centre +ve. When powering it up from the correct PS, IIRC it showed a number 1 on the display and wouldn't do anything. I say IIRC because I couldn't find a correct supply to test it with.

I understand these units are fantastically unreliable and difficult/impossible to fix? I wonder if anyone's fixed a broken one.

It wouldn't matter, except I remember the thing, despite having an atrcious UI, as being a whole heap of fun to play with!

Any ideas out there, dear E-M-ers?
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gwaidan



Joined: Mar 07, 2009
Posts: 53
Location: Sydney, Australia

PostPosted: Sat Jan 02, 2010 7:47 pm    Post subject: Reply with quote  Mark this post and the followings unread

I fixed mine a while back. The Power supply section is really poorly designed, and part of this is that there is no reverse voltage protection, so plugging in the wrong plugpack will eventually kill the 7805 regulator. I replaced my 7805 without too much hassle a few months back, and took the opportunity to add some stabiliser caps across the legs of the regulator, and now all works well.
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gwaidan



Joined: Mar 07, 2009
Posts: 53
Location: Sydney, Australia

PostPosted: Sat Jan 02, 2010 7:52 pm    Post subject: Reply with quote  Mark this post and the followings unread

If you are getting *something* on the display on powerup, then more likely is that a random power glitch caused by a loose connection has trashed the memory contents (there is no buffer capacitor at the power-in)-try doing a hard reset by holding the "enable" button as you start up the unit.
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CJ Miller



Joined: Jan 07, 2007
Posts: 371
Location: 127.0.0.1

PostPosted: Fri Jan 08, 2010 2:50 am    Post subject: Reply with quote  Mark this post and the followings unread

I have had to replace PerfX regulators as well. Be sure to add that diode! If you need the firmware ROM, I upped it to an Oberheim Yahoo group a while back, or PM me.

These babies appear to be bog standard 80C31 boards, with just a few switches and LEDs, and MIDI. I have seen all of them except the Strummer, it appears that they are all exactly the same PCB. One project I have been wanting to do is have switch enabled EPROMs and SRAM so I can set it to be any of the PerfX boxes I want at the time.
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gwaidan



Joined: Mar 07, 2009
Posts: 53
Location: Sydney, Australia

PostPosted: Fri Jan 08, 2010 5:04 am    Post subject: Reply with quote  Mark this post and the followings unread

Second that-the only distinguishing thing about the module seems to be the contact adhesive plastic showing the function matrix and the ROM, and all else seems generic to the series - would like to try the Drummer EPROM myself one day!

There used to be a really detailed guide on the web with photos showing how to upgrade the power supply circuitry-if I find it again I will post a link
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Norman Phay



Joined: Jun 29, 2007
Posts: 173
Location: North-East England
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PostPosted: Thu Jan 14, 2010 12:03 pm    Post subject: Reply with quote  Mark this post and the followings unread

Well, anyone who successfully attempts surgery on an Oberheim perf-x board is a hero to me. I've repaired mistakes on quite a few things I've built, and lifted I think 2 pads ever. On the perf-x board, every damn pad I so much as touched w/the iron lifted! VERY ANNOYING. I Tried to replace the voltage rectifier, but got nowhere, unfortunately. The pads lifted, as well as a trace, and I couldn't get a voltage at the 2 test pins. I did manage to replace the soldered in battery with a CR2032 holder, the pads lifted on that too, but my repair with a little length of wire worked. So, I'm still stuck! That page showing how to update the PS sounds useful, I wonder if it still exists somewhere?
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gwaidan



Joined: Mar 07, 2009
Posts: 53
Location: Sydney, Australia

PostPosted: Thu Jan 14, 2010 2:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yep, I had the same problem-luckily the pads on the bottom of the board held for my regulator.
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julianw



Joined: Jul 30, 2007
Posts: 78
Location: UK

PostPosted: Mon Mar 22, 2010 5:08 am    Post subject: Reply with quote  Mark this post and the followings unread

gwaidan wrote:
There used to be a really detailed guide on the web with photos showing how to upgrade the power supply circuitry-if I find it again I will post a link


Was this the site?
http://pics.studiorepair.de/Oberheim/Cyclone/index.html

I'm looking at doing this mod with 1uf caps on the 7805 regulator input and output, also looking at removing the big ferrite beads and replacing them with shorter beads with diodes in series.


Oberheim Cyclone Modified 7805.jpg
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Oberheim Cyclone Modified 7805.jpg


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gwaidan



Joined: Mar 07, 2009
Posts: 53
Location: Sydney, Australia

PostPosted: Mon Mar 22, 2010 6:28 am    Post subject: Reply with quote  Mark this post and the followings unread

Yep, that's the one. I'd consider doing 220uf on the input and 22uf on the output of the regulator, and you could fit the diodes under the ends of the inductor legs
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Ricoche



Joined: Dec 19, 2009
Posts: 8
Location: Nagano, Japan

PostPosted: Wed Dec 04, 2013 9:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hello! I recently acquired an Oberheim Cyclone with the now it seems infamous symptom of locking up after a minute or two of use. Has anyone come any closer to cracking this cold case? For now it seems, swapping boards with a Strummer for example is the only answer.
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Jim Atwood in Nagano-city, Japan
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