“This is a working 5 voice Oberheim OB-SX synth.
New bushings were installed and the keyboard leveled.
The synth needs some attention. Some double triggering, keyboard contacts should be cleaned to help resolve this. Synth should also be calibrated to keep in tune better across the keys. The power button light stays on even when switched off. Strange, though it doesn’t affect anything. Several screws missing from end pieces.
All buttons and switches appear to be working, though I’m not sure what “Narrow / Broad” switch does, I didn’t hear a difference.
“Hold” and “Chord” buttons work by holding a key, then pressing “Hold” then “Chord.”
I typically turn on synth, wait a few minutes, then hit “Auto” in order to tune. As stated, it needs calibration to be in better tune, but there are plenty of sounds that play wonderfully as is. See videos.
This Oberheim is being sold “as-is” with no returns, due to its vintage nature and commotion during shipment. Get it tuned up or use it for parts for another Oberheim.” Click here to visit listing on eBay
“Oberheim OB-SX Vintage Analog Synthesizer. This unit is being sold as. Powers on and produces sound but the first two voice cards light up but do not seem to produce any sound. May need to be calibrated.” 
“Oberheim OBSX, 6 voice with 56 memories in mint condition.