Rhodes Chroma Polaris

Hello

My Chroma Polaris II has an issue where the sweep red light doesn't work. All other membrane panel switches and lights function properly. It used to work and due to a long period of touring away from the synth I cannot say when it stopped working.

I have just completed the membrane panel update and that has went well. It didn't cure the issue with the sweep light not coming on. Perhaps someone could point me towards which things in the polaris I should be looking at specifically or is having a light go out a likely possibility? if there is some particular connector I should be looking at, or wire, or whatnot. I'd just like to be pointed in the right direction so that I could possibly troubleshoot this some more while the synth is still apart.

Paul Kavicky
www.paperstreetaudio.com

> From: Paul Kavicky
>
> My Chroma Polaris II has an issue where the sweep red light
> doesn't work. All other membrane panel switches and lights
> function properly. It used to work and due to a long period
> of touring away from the synth I cannot say when it stopped working.
>
> I have just completed the membrane panel update and that has
> went well. It didn't cure the issue with the sweep light not
> coming on. Perhaps someone could point me towards which
> things in the polaris I should be looking at specifically or
> is having a light go out a likely possibility? if there is
> some particular connector I should be looking at, or wire, or
> whatnot. I'd just like to be pointed in the right direction
> so that I could possibly troubleshoot this some more while
> the synth is still apart.

Are you saying that the function works, but the LED stays off? It's most
likely just a bad LED, although you can check this with a multimeter by
measuring the voltage across it when it is supposed to be on. If the LED is
open, the voltage will be a typical TTL logic 1 output voltage of at least
3.5V. If the shift register is bad, it will be less than the on voltage of
the LED, which is about 1.5V. I believe the LEDs we used predated the
high-efficiency LEDs that are available now, so try to find a crappy old
low-efficiency one, or the replacement will look a lot brighter.

There was also an issue with the shift registers that drive the LEDs
sometimes being mis-clocked by ground noise, which was solved in many
production units by soldering a capacitor around 0.1uF between the digital
ground on Z6 pin 7 and the nearby LED ground bus. If that mod has already
been done, it will be clearly visible on the circuit side of the board way
over on the left end of the panel. If it has not been done, tacking a
capacitor in there may help.

If the function doesn't work either, recheck the alignment between the tails
on that side of the panel and the connector. But it's hard to imagine
misalignment only affecting one switch, instead of a whole matrix row or
column.

Any feedback on the membrane replacement process? Were the directions clear?
Anything I should change?

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...

the switch and slider both function, so I continue to suspect it's just the LED.

Thanks much for the new panels. Installation was not a problem at all, and went slightly faster than I thought it would. Looks and works great, and a nice gentle push makes all the switches work. The instructions were excellent.

The sockets that the membrane tails feed into are not as tight on mine as I suspect that they used to be, so I'm resorting to putting some gaff tape on the back of the membrane leads to thicken them up a little assuring contact in those sockets.

Otherwise things are ok. I ordered a replacement LED this morning, so I'll solder that in next week.

--- In chromapolaris@yahoogroups.com, "Paul D. DeRocco" <pderocco@...> wrote:
>
> > From: Paul Kavicky
> >
> > My Chroma Polaris II has an issue where the sweep red light
> > doesn't work. All other membrane panel switches and lights
> > function properly. It used to work and due to a long period
> > of touring away from the synth I cannot say when it stopped working.
> >
> > I have just completed the membrane panel update and that has
> > went well. It didn't cure the issue with the sweep light not
> > coming on. Perhaps someone could point me towards which
> > things in the polaris I should be looking at specifically or
> > is having a light go out a likely possibility? if there is
> > some particular connector I should be looking at, or wire, or
> > whatnot. I'd just like to be pointed in the right direction
> > so that I could possibly troubleshoot this some more while
> > the synth is still apart.
>
> Are you saying that the function works, but the LED stays off? It's most
> likely just a bad LED, although you can check this with a multimeter by
> measuring the voltage across it when it is supposed to be on. If the LED is
> open, the voltage will be a typical TTL logic 1 output voltage of at least
> 3.5V. If the shift register is bad, it will be less than the on voltage of
> the LED, which is about 1.5V. I believe the LEDs we used predated the
> high-efficiency LEDs that are available now, so try to find a crappy old
> low-efficiency one, or the replacement will look a lot brighter.
>
> There was also an issue with the shift registers that drive the LEDs
> sometimes being mis-clocked by ground noise, which was solved in many
> production units by soldering a capacitor around 0.1uF between the digital
> ground on Z6 pin 7 and the nearby LED ground bus. If that mod has already
> been done, it will be clearly visible on the circuit side of the board way
> over on the left end of the panel. If it has not been done, tacking a
> capacitor in there may help.
>
> If the function doesn't work either, recheck the alignment between the tails
> on that side of the panel and the connector. But it's hard to imagine
> misalignment only affecting one switch, instead of a whole matrix row or
> column.
>
> Any feedback on the membrane replacement process? Were the directions clear?
> Anything I should change?
>
> --
>
> Ciao, Paul D. DeRocco
> Paul mailto:pderocco@...
>

> From: James
>
> The new Polaris membrane panel replacements arrived today.
> Well packaged to boot.
>
> Paul did an OUTSTANDING job on these and the price is right.
> They are cosmetically identical to the original panels but
> the pig tail connectors are made out of a much more flexible
> material. After seeing them, I now understand the importance
> of getting them right. Folks, this is top notch work from a
> design and manufacturing standpoint.
>
> My original panels still work but are on their last fix and
> the last precious millimeters of usable ribbon will
> eventually crumble into dust sooner rather then later. After
> this, the synth would have been done had Paul not taken on
> this project.

Thanks for the kind words, James. When you eventually do install them, I'd
appreciate any feedback you might have on the instructions.

Also, they're not quite "identical". The most obvious difference is that on
the old panels the word SEQUENCER was done in a slightly smaller font than
the other titles, which always bothered me. So it is possible, if you know
that fact, to tell at a glance whether a Polaris has the new or old panels.

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...

Just an update.

My last order for the 10 slot connector arrived yesterday so was able to replace the 5 and 10 slot ribbon connectors for the left side panel since mine were desoldered and extended with wire as a last resort repair.

The installation went perfectly well and took about 2 hours taking my time. Paul's panels work and fit 100 percent.

If you need fresh 5 or 10 position tyco connectors, I have about eight 5 slot and about twenty 10 slot spare connectors due to minimum ordering requirements. Drop me a line, I'd be happy to throw one in the mail.

James

--- In chromapolaris@yahoogroups.com, James <fl_799@...> wrote:
>
>
>
>
>
> ________________________________
> The new Polaris membrane panel replacements arrived today. Well packaged to boot.
>
> Paul did an OUTSTANDING job on these and the price is right. They are cosmetically identical to the original panels but the pig tail connectors are made out of a much more flexible material. After seeing them, I now understand the importance of getting them right. Folks, this is top notch work from a design and manufacturing standpoint.
>
> My original panels still work but are on their last fix and the last precious millimeters of usable ribbon will eventually crumble into dust sooner rather then later. After this, the synth would have been done had Paul not taken on this project. 
>
> James
>

Here's a shout out to James who was kind enough to send me a few 5 and 10 positionTyco connectors for my panel replacement.