Oberheim Dmx (1981)

Cult drum machine based on EPROM SAMPLES with internal sequencer, (great swing!) no Midi but some sync options for real-time perforamances.  The main panel features a fluorescent display, 10 sliders for volumes mixing, 24 buttons for edit and 18 trigger pads with no velocity. You can read it HERE more information  about the DMX

Meet me at the parking...

Selling my DMX some times ago was a pretty stupid move. Slowly I am purchasing back some of the stuff from the past at a reasonable price, especially if it's for repair. In the mean time I got an Oberheim DX, but but... not really the same.

Finally found a good bargain in Facebook Markeplace (This never really happened). The seller is from Como and told me It has not been turned on for more than 10 years (just a bit worried about battery leakage). We finally managed to meet in a parking somewhere around Saronno. After some nice conversation, the DMX was ready for the trunk of the car-

What's wrong with it?

Well, the machine is nice and good working except the CYMBAL board that was a bit out of the slots (these happened often with my OBXA some time ago).

Thanks God, no leakage, nice shape, just a bit of cleaning but overall very nice condition. Some Switch buttons are a bit stiff, the sliders are sluggish, but really nothing important.

NOTE I am using picture from the DX which has the quite same structure, buttons and sliders.

UPPER   Opening the DMX-DX is really easy, just remove the frontal handscrews (UNPLUG ALSO THE POWER btw). You have to remove all knobs from sliders and fifteen 1/4 inch nuts on each corners of the panel board. 

Before  / After cleaning

UPPER  - The board was full of dust anywhere, as well around buttons and sliders. Just good, very good rubbing alcohol to clean up that mess. Now it's nice and shiny, smelling like spring.

UPPER You have to be really careful opening the buttons: a Flathead screwdriver on each side and it should pop up the plastic cap with a click. Buttons on the numeric pads have less space to use screwdriver, so I preferred to desolder them for easier access. Clean the coil spring with deoxit and maybe with a knife scratch the dirt on both contacts.
NOTE: the DX have some DIODES on the buttons that break really easy.  The DMX does not. 

Slider pots

Now the sluggish scratchy pots. When these are dirty, they get stiff to move with sloppy movement. Best move is to remove all of them and not spray at random some products that make a kind of goop.

Each slider have 2 screws and some 2 wires soldered (plus common ground: DX is an insulated wire, while DMX is solid metal).  The overall volume is of course stereo.

UPPER: Gently pry the metal tabs to open the slider.
The slider is composed by four parts: clean all dirt with soap or alchool, remove everything sticky. The contact with shaft must cleaned also of scrached with knife to remove oxidation. It's a nice idea to add a drop of silicone grease on the sides for smooth effect.

Reassembling and testing

Well it sounds VERY NICE! ok there are dozen of samples around, but this another story!

If you need:

-Oberheim DX service manual

-Oberheim DMX service manual


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