The VFX series - and to a lesser extent, some other Ensoniq keyboards - often suffered from a KEYBOARD CALIBRATION ERROR
when booting up. The problem is from a faulty connection between two circuit boards directly underneath the keys. If you get
this error message, after you press a button, the display will give you the option to RECALIBRATE or IGNORE. If you recalibrate,
it is likely you will get the same result. If you ignore, your VFX or SD-1 will still work normally - except that the keys will be
disabled. While that may seem pretty pointless at first, it does allow the synth to be played via MIDI. You can also play back
sequences.
In a pinch, you can often get the keyboard to calibrate by performing the "Heimlich manuever". Lean the keyboard against a wall
at a bit of an angle, then press gently in the middle of the top panel just above the keys. (The faulty connector is in the middle
of the keyboard.) This can be just enough pressure to temporarily restore the faulty connection. But it is at best a temporary fix.
The real solution is to remove the keyboard, and hard-wire the connector that bridges the two keyboard coil boards. On one side of
these two boards is the brown connector that mates them together. On the opposite side of the boards, where the pins of these
connectors are soldered to the PC boards, you can simply solder some jumper wires which make the same connections.
