Oberheim Xpander – 2

Pot and Display PCBs

Overview In 2021 I acquired a set of original Oberheim Xpander PCB’s – the Voice and Processor boards, so that I could build my own Xpander at around £2000. This is an expensive and crazy project that requires lots of difficult to source parts.

In 2021 I bought the CEM3372 and CEM3374 chips, and waited until the “Elephant in the Room” had been addressed. I also bought wooden ends so I could get some of the panel dimensions, and panel switches and buttons. I have not located all the correct caps.

Membrane Display

Membrane Panel This is the “Elephant in the Room”, as I cant make a membrane and have to wait until one is remanufactured. In late 2021 Sweet Discrete announced they would make the panel if they got 200 orders (see mock up picture).

I jumped in at order 196 in February 2022 and there are only 4 more orders need to get the membrane into production. I am confident this will happen, so I can start planning the rest of the build. Sweet Discrete make a wide range of replacement membrane panels and are highly recommended.

Pot PCB A smaller “elephant in the room” is that I don’t have a Pot PCB, and I will have to make one, using the membrane panel as a template. This will take a few weeks to lay out and check before ordering one. A one off PCB this size is around £300, so its a major expense and something I have to get right. Whilst a NOS Display PCB is available, the new VFD displays mean I don’t need to use one.

Metal Chassis I need to design a metal top panel, which I will do in CAD software. This will be expensive to have made as a “one off”. The bottom panel may be based on a Roland D-50 base plate. I doubt anyone has an old Xpander chassis but I will keep searching!

Xpander Encoders

Next Big Purchases The next step, in parallel to the Pot PCB design, is to gradually buy the major components needed for an initial build and test;

• New VFD displays £400
• Switched power supply £400
• Processor logic chips and OS chips £200
• New set of encoders £100

The Xpander Mockup Panel was created by Sweet Discrete and the image is their copyright – More in Episode 3!