Assembly - TM-3 Prophet-600 Keyboard Kit

Techsmechs Vintage Synth | Stockholm, Sweden


  • The kit includes: 61 key semi-weighted keyboard with cable assembly, Adapter card, 3 steel Mounting plates. Plastic bag with 6 pcs M4x16 hex machine screws and an allen wrench.
  • Find a good space to work, with a table and nice lighting. Put  a towel or something soft on the table to avoid scratches.
  • Static electricity is bad for electronics so avoid (wall to wall) carpets and rubber shoes.
  • Take your time, work slowly! Pro tip: Read through these instructions once before even starting!
Side panel screws
Prophet-600 side panel screws
The keyboard connector
Prophet-600 keyboard connector

Removing the old keybed

  • Place the Prophet-600 on a table. (Of course it should be completely disconnected.)
  • Put the P-600 on its "back" and loosen (don't remove) the 6 screws holding the keyboard in place.
  • Put the P-600 back down in its normal position.
  • Remove the 2 top screws from both wooden sides (see pic), and open the lid.
  • Pull the 16 pin cable going from the keyboard to the connector on the PCB in the lid (see pic).
  • Pull one side of the P-600 over the edge of the table slightly, so you can reach the screws holding the keyboard in place. Unscrew them fully. Then do the other side and the 2 screws in the middle.
  • Lift out the old keyboard and put it away. The 6 screws for the old keyboard will not be needed for the new one.
Cutouts to make room for capacitors
Fatar cutouts vs caps
Cut these pot legs
Prophet-600 pot leg cuts
Gently bending caps
Gently bending caps to make room

Fatar modifications summary

Placing a modern Fatar keybed in a Prophet-600 is a tight fit. Its physical dimensions are slightly different.

We have modified the keyboard in some places to make it fit:


  • The top C key has a thin bit removed at the bottom.
  • 5 mounting studs are removed.
  • 6 slots have been cut in the bottom to allow for free space around some capacitors on the P600 voice board (see pic).


Preparing the P-600 for the new keybed

Some preparations need to be done to the P-600 as well. It does not affect the sound or functionality in any way.


  • Using a pair of cutting pliers, shorten the legs as much as possible on the 5 potentiometers closest to the front: Speed, Attack, Decay, Sustain and Release (see pic). 
  • On the big circuitboard in the bottom of the P600 (board 4), carefully bend the green capacitors a little to make room for the Fatar: on my unit it worked best to bend 2 one way and 1 the other way. (see pic)
The adapter card in place
The Prophet-600 adapter card in place


  • Carefully place the TM-3 keyboard in the P-600. 
  • Inspect that the notches made in the bottom of the Fatar line up with the electrolyte "can" capacitors on the voice board and that the green capacitors are not touching the Fatar.
  • If all looks good so far, pull the P-600 over the edge of the table slightly, so you can mount the 2 "outer corner" screws using the provided black hex screws and allen wrench.
  • Do another visual inspection of the caps so nothing is stuck or squeezed.
  • Again pull each side of the P600 over the table edge so you can screw in the remaining screws. As you tighten things, keep an eye on the notches made in the bottom of the Fatar, make sure there is enough space so the capacitors on the voice board don't touch it. Also test the keys, especially the top and bottom C keys so they don't get stuck on anything.
  • The keyboard should now be securely in place with all six screws. All good?
  • Connect the adapter card to the 16 pin connector on the PCB in the lid, cables pointing upwards.
  • Close the lid, but before final assembly give it a test run: connect power and audio, and test all the keys.
  • All ok? Ok then put the 4 black screws back in the wooden sides
  • Done!