Old, dead Oberheim Cyclone

[norman phay]

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?

[gwaidan]

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.

[gwaidan]

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.

[CJ Miller]

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.

[gwaidan]

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

[norman phay]

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?

[gwaidan]

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

[julianw]

[gwaidan]

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

[Ricoche]

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.