Rhodes Chroma Polaris

From: "teknowh0re_1999"
...
> I've owned my Polaris for about a year now, and it has the infamous
> membrane button death. I've opened it up a time or two but not gotten
> too adventerous until tonight. Long story short, the jumpers
> connecting the PCB to the membrane panel are pretty much dead (deader
> than they were). But when I say "jumper" I mean "leads in a thin
> plastic sheet."
>
> Can I simply solder in some jumper cable or wires from the PCB to the
> membrane panel or do I need to think about using this machine for
> spare parts?

If the problem is with one or more of the plastic strips that come from the 
front panel and slide into connectors on the circuit boards, then soldering 
will be tough.

The plastic/mylar normally has a conductive coating on it, and that's what 
transfers the signals to the circuits.

The most common polaris sickness will be a cracking of that plastic - and as 
the plastic cracks, the signal traces are broken.  In many cases, the 
cracking occurs at the end of the connections - and so you can get lucky by 
trimming off the bad end with a pair of scissors.

If the crack/rip/tear is too far away from the connectors to make cutting 
likely, then there are a couple alternatives:

1) Try to physically repair the crack by gluing/attaching another piece of 
plastic to the broken piece.  This will not necessarily repair the 
electrical conductivity, but it will be the mechanical support for the 
connection.  Once mechanically secure, the trace itself can sometimes be 
repaired via a 'conductive ink pen'.  They sell these at electronics stores 
(and on-line), and they're specifically made for this sort of a task.  You'd 
hold them like a pen, and then 'draw' the connections you need.  Once dry, 
the connections can pass the signals you need.

2) A slight variation of #1 (and this is if you're desperate), would be to 
try to 'stitch' a fine wire back and forth between the broken track.  (Think 
of it just like a needle and thread - but instead of holding material 
together, you'd be holding the traces together).  Certainly not ideal, and 
depending how brittle the connector is, may cause more damage than it fixes.

You can have even more variations, with wires being fished up between the 
layers of the front panel - but these are really last-gasp sort of 
solutions.

3) If all else fails, then you'd be looking to forego the use of the actual 
membrane switches, and to add in your own switches (which you'd wire in with 
real-wire instead of the plastic).  These switches could be mounted right 
on/through the original panel, or they could go in an external box.

In the short-term, it is the case that the parameters can be controlled from 
MIDI - so an external MIDI knob-box (or access from a sequencing program) 
could be used.