Roland D-70 Super LA Synthesizer


A few years ago I bought a broken Roland D-70. I recently came across the pictures of the repair so I’m sharing this just in case anyone needs help fixing their D-70 πŸ™‚

Technical specifications:

  • Polyphony – 30 voices
  • Oscillators – Digital ROM samples and DLM (“Differential Loop Modulation”)
  • LFO – YES
  • Filter – TVF FILTER: low-pass-resonant (like D50).
  • VCA – TVA (like D50).
  • Effects – Reverb, Chorus, Flanger (like D50)
  • #Instruments – 5-parts + 1-percussion
  • Keyboard – 76 note keyboard with velocity and aftertouch
  • Arpeg/Seq – None
  • Memory – 10 user sets, 64 performances, 128 patches, 128 tones.
  • Control – MIDI
  • Date Produced – 1990-91

The D-70 I bought had problems with the keybed. Apart from the Red Glue issue a lot of keys on the left hand side of the keyboard didn’t work. At home I took it apart to find out that the construction of the keybed is identical to the U-20, D-5 and JD-800 (and probably some others including the KR-series I think)

These are very nice keybeds to play but they used a very flimsy pcb (circuitboard) made of a thin plastic film which is extremely fragile.

The D-5, U-20 and JD-800 have a single pcb running underneath the keys but the D-70 has 2. I’m borrowing this picture from a D-5 I repaired but this is how the connector should look:


A D-70 has a connector just like this one the left and right hand side of the keybed. It’s 2 plastic parts glued together and then held together by a transparant plastic strip. Very fragile. If you disconnect this you most likely destroy the 16 traces that are in the flexible ribbon cable and it will never work again.

If you ever buy a D-5, U-20, D-70 or JD-800 and only a few keys don’t work it’s probably a matter of cleaning the key contacts but it a lot of keys don’t work anymore it could be this connection that has come loose.

Some repair this by replacing the plastic strip by a metal one to apply pressure to the connection. Sometimes this works.. I tried it on my D-70 but pretty much all the keys on the left hand side stayed dead.

Roland sells a replacement part for this. The white ribbon cable and the green flexible pcb are nowΒ one part instead of two. So no more fragile connection. You will also need a new little pcb that’s on the back of the keybed (where the white ribbon cable goes to). I’ve asked for a quote and it costs around a 150 euro’s.. Since a mint D-70 is worth about a 100 euro’s I didn’t buy the part.

Here is how I fixed it. Hackish? Hell yes, but it works like a charm πŸ™‚

I used 16 wires from a standard network cable. I glued them to the green pcb with a strong glue (the yellow / brown stuff). This is just to keep them in place. Then I used ‘Wire Glue’ which is an conductive glue to glue the 16 wires onto the traces of the green pcb.

After I tested for continuity I soldered all 16 wires to the small pcb where you would normally attach the white ribbon cable. This was not a very easy job and I don’t know if I ever want to do it again πŸ™‚

Well, at least I saved one D-70 from the scrap heap πŸ˜€


4 thoughts on “Roland D-70 Super LA Synthesizer

  1. What type of wire glue do you use? I bought some graphite based wire glue and it did not close the circuit when tested with a multimeter.


    1. Hi Ken,

      I’m not sure but by the looks of it it might work.. Caikote 44’s main use is to fix the conductivity of rubber contacts but it’s glue and it conducts electricity so it might be worth a try.. on the other hand: wire glue isn’t really expensive..

      grtz, Jorick


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