Recently I bought my second Juno-D. It has the exact same problem as the first one I bought (and probably any other Juno-D on the planet): only a handfull of keys work.
If you have a keyboard or synthesizer and one or two keys don’t work take it apart and clean the contacts underneath the keys. If you have a Juno-D where out of 61 keys 58 don’t work don’t bother cleaning the contacts. I’ve tried this with the first Juno-D. Didn’t work. Order new contactstrips:
4 x 04230834 RUBBER SWITCH 12P FOR ROLAND JUNO-D
1 x 04230845 RUBBER SWITCH 13P FOR ROLAND JUNO-D
The first set cost me EUR 23,50- last year and the set that came in this week cost me EUR 30,- Inflation I guess. 😛
This is how you replace the contactstrips:
Turn your Juno-D upside down. I always place it on some towels to protect the buttons. Remove the bottom plate (yes I know: that’s a lot of tiny little screws).
Disconnect the flat ribboncable from underneath the green PCB. It’s necessary to remove the screws from the back of the Juno-D so that you can lift the PCB and disconnect the ribboncable. Never disconnect the centre connector as that might permanently damage it in this case.
After you undo all the screws keeping the keybed in place you can slide it right out. Remove all the springs you can see in the picture above and remove the keys. This might be a good time to give the keys a nice bath in the kitchen sink 🙂 Don’t use boiling hot water as that can deform the keys. This particular Juno-D was remarkably clean inside and outside. (check the D-5 project to see how much dust and dirt can accumulate in a synth)
You can now see the rubber contactstrips. Pull them right off and put them in your trashcan. Don’t try and sell them on Ebay like some moron is doing right now.. (this guy on Ebay sells used parts for a Juno-D at insane prices.. a 5 dollar ribbon cable for 50 dollars, used keys for 12,50 each (5 bucks new) 85!!!!! dollars for used(!!!) contactstrips which are 25-30 dollars new.. you can buy all his Juno-D parts or a brand new car. You choose :-))
This is a great time to clean the gold coloured contacts on the PCB with Q-tips and cleaning alcohol.
As you can see the new contactstrips look a little different then the old ones. The fact that the rubber ‘legs’ are shorter makes it a whole lot easier to replace them. The old strips are part of a bad batch I think. Since they all go bad.. The black carbon dots just stop conducting electricity after a few years. Usually these strips last decades and only require cleaning sometimes. I’m hoping these new strips don’t go bad after a few years..
When replacing the contactstrips take note that the height of the carbon dots is different. The taller one goes at the back. It’ll only fit one way but if you manage to mount the strips backwards the keys won’t be velocity sensitive anymore. They will always sound at 100% volume.
Reassemble and see if all the keys work again. If so: have beer 🙂