Synthesizers of this era relied on mechanical components to select and vary controls.  Toggles to switch between settings or switch them off, sliders and pots to vary resistance and incrementally change the magnitude of a filters effect/strength of amplification/rate of change etc and momentary switches to change logic states. This afternoon I removed and cleaned up all the momentary switches that control the wave forms, chorus settings, presets and write capabilities.  If this thing was a little cleaner I would have cleaned them on the boards, but as can be seen below, the boards are pretty dirty and removing them was only a few minutes work.

Pretty gross build-up on these switches and on the circuit board below them.  I pulled the middle switch the other day to see why it didn’t work -it was missing the little contact button.  There’s one of those Hitachi HD14051BP’s that are probably about to hit the endangered IC species list.

These guys are an earlier style of switch Roland used.  The ‘Key Transpose’ is a momentary switch, changing a logic state to transpose the key while the ‘hold’ and ‘arpeggio’ switches have a detent for on or off.

While I’ve been at other tasks I have tried out some plastic whitening recipes.  This afternoon -after two days soaking in this solution with it in the sunlight, all but the white buttons look good as new -and the white ones are 80% improved.

Here are the switch parts all lined up after being cleaned with Simple Green.  Nothing dries like sunlight and time.

I’m trying to decide if these foam blocks that live under the colored caps are meant to keep dust out of the switches, help the little springy rubber contacts push the white part of the switch up or something else.  I am a few short and will have to make some.

That little blue-green deal inside the switch body acts as the holder for the graphite contact, a dust protector and a return spring.  I need one.  Don’t know where I’m going to find one.  Anybody got an extra?

Assembly procedure is simple: put the little blue-green contact in, slide the white inner switch slider in, put the piece of foam in the open side then snap the cap on.

Here they are all lined up and ready for action.  I have a few more to remove from the other board -I ran out of de-soldering wick of the appropriate type.

I’ll be digging in to the panel circuit boards tomorrow to replace some capacitors, reinstall these switches and some general clean up.

Part 5 is here.

Part 7 is here.