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Tom Oberheim SEM Pro Repair – Synthchaser #139

In this video we have a look around inside the new Marion Systems Tom Oberheim SEM Pro. And thanks to the kindness and generosity of Tom Oberheim himself, we’re able to repair a problem this one is having with an envelope randomly getting stuck “on”. The birds in my area love Oberheims (remember the OB-Xa Hummingbird?), and a Red-Tailed Hawk comes to check out the repair job.

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Synthchaser Update September 2020

Lots of exciting things brewing! First, I’ve dusted off my ARP Omni MIDI project and have just about finished it up. Hardware design is finished, a couple prototype boards are currently in production and I expect to finalize the firmware and make the adapters available next month.

Another project I’m working on is replacement voice cards for the Oberheim OB-Xa (later I’ll do ones for the OB-SX). I got my hands on a 4 Voice OB-Xa and it was just begging for more voice cards… So I’ve made a faithful recreation of the OB-Xa cards. These will begin shipping in early October–stay tuned for an announcement with more details.

This month I finished restoring a pair of ARP Quadras (pictured here at the back of this trio of red, white & blue Quadras). One for a customer in blue, and one of mine in red which is now available to purchase on my website. With this latest Quadra, I added a pot (inside the synth so no drilling was done) to dim or even fully turn off the illumination. With the fader caps I installed and the LEDs turned off, it looks very close to original, but performs way better than original.

Finally, I have a bunch of ideas for new videos, and now that I’m close to finishing a bunch of longer-term projects, I should have a little more time to film some new videos for you guys!

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Synthchaser Update August 2020

Since my video posts have slowed down during this pandemic (more on why below), I thought I’d start making monthly blog posts just saying what I’m up to and working on. 

For the past few weeks I’ve been doing a double header restoration of 2 ARP Quadras.  One is a customer’s machine, the other is one of mine that I’ll be selling when I’m done (if you want a nice Quadra, drop me a line!).  I thought the LED sliders that I made for the Jefferson Starship Quadra turned out really well, and I’m putting them in these new Quadras as well.  I’m going to try hooking in a PWM module, so the LEDs can be dimmed or disabled with the turn of a knob.

Oberheim owners might want to follow this one.  I recently picked up a 4 voice OB-Xa and decided it was time to make replacement voice cards.  So I’ve laid out a circuit board (I teased this on Facebook and Instagram and was surprised people could identify it from a low-res CAD drawing), and had a few blank circuit boards made.   I need to find some time to build and test one, but the plan is when I’m done, I’ll make these available as pre-built boards, and possibly blank PCBs for those interested in building their own.  I’ll also be making voice cards for the OB-SX because the OB-SX voice cards are a subset of the OB-Xa cards (and I also have a 4 voice OB-SX!).

As most of you know I’m in California.  I’ve got kids and the lockdown and school closures really cut into the time I had to work on synthesizer repairs and shooting videos.  Many of you have asked over the past few months if I could repair some gear and I’ve turned you away for this reason.  I know there are people who will take your gear and sit on it for months or years before fixing it (or before you demand it back and get it back in worse shape than when it went in…), but that’s not how I roll.  If I can’t turn your repair around quickly, I’ll be up front about it and I won’t take your gear in.  Anyway, we just found out that our schools aren’t opening to in-person learning until at least January 2021.  So definitely feel free to ask about repairs, but please be understanding if I can’t take your gear in now.  I am still shipping parts orders, and I still ship parts internationally, though I’m seeing that most international mail is significantly delayed due to COVID-19.

Thank you all for your continued interest and support, and stay well!

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Synthchaser #098 – Oberheim DSX Sequencer Repair

Today we repair an Oberheim DSX sequencer that was sparking and smoking when I first turned it on. We clean up nasty battery corrosion, repair a short circuit, rebuild the power supply, replace a broken display, install my battery eliminators to make sure we never have another leaked battery, and we test the sequencer with the diagnostic ROM and with a real OB-Xa synthesizer.

 

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Synthchaser #097 – Battery Eliminator for Oberheim OB-Xa, OB-8, DMX and DX

Introducing the Synthchaser battery eliminator for your Oberheim vintage synths and drum machines! Never have to change the battery again, or worry about it leaking and damaging your machine. In this video, I show how to install the battery eliminator in an OB-Xa to save presets without a battery installed in the synth!

Synthchaser Battery Eliminator for Oberheim OB-Xa Synthesizer

Synthchaser Battery Eliminator for Oberheim OB-8 Synthesizer

Synthchaser Battery Eliminator for Oberheim DMX & DX Drum Machines