Rhodes Chroma Polaris

My Polaris has worked fine for many, many years. It has been turned on pretty much nonstop for 20 years. No problems. Recently I did a rare live show, and turned the beast off to move it. When I turned it on again, all the panel LEDs lit and there was no sound. Unplugging and replugging the pedal and sustain switch jacks seemed to clear up the problem. LEDs went back to their regular behavior and the correct sounds returned. When I moved the synth back home, I got the same weirdness with the LEDs all lighting and no sound, but replugging jacks and cycling power didn't have any effect for a day or so. Then, about a day later, it seemed to work: the LEDs went back to their correct settings, and the sounds came back. But they are all at about a quarter of their previous volume. I tried doing the adjustments listed on page 108 of the manual. But there is a problem with those directions. They instruct you to "turn the MASTER slider all the way up", and then to "raise the MASTER slider until you hear the note just begin to bleed through". I don't understand how you can raise the slider any more after it is "all the way up". I haven't had any luck playing around with this. I have tried pressing LF, Adjustments,9 twice, without any perceptible change. Anyone ever run across this weirdness? Thanks!!

> From: Dan Stefacek
>
> My Polaris has worked fine for many, many years. It has been
> turned on pretty much nonstop for 20 years. No problems.
> Recently I did a rare live show, and turned the beast off to
> move it. When I turned it on again, all the panel LEDs lit
> and there was no sound. Unplugging and replugging the pedal
> and sustain switch jacks seemed to clear up the problem. LEDs
> went back to their regular behavior and the correct sounds
> returned. When I moved the synth back home, I got the same
> weirdness with the LEDs all lighting and no sound, but
> replugging jacks and cycling power didn't have any effect for
> a day or so. Then, about a day later, it seemed to work: the
> LEDs went back to their correct settings, and the sounds came
> back. But they are all at about a quarter of their previous
> volume. I tried doing the adjustments listed on page 108 of
> the manual. But there is a problem with those directions.
> They instruct you to "turn the MASTER slider all the way up",
> and then to "raise the MASTER slider until you hear the note
> just begin to bleed through". I don't understand how you can
> raise the slider any more after it is "all the way up". I
> haven't had any luck playing around with this. I have tried
> pressing LF, Adjustments,9 twice, without any perceptible
> change. Anyone ever run across this weirdness? Thanks!!

I think that means that you begin by turning the master volume all the way
up, so you can better hear the bleedthrough when you begin to do the actual
adjustment.

--

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

> When I turned it on again, all the panel LEDs lit
> and there was no sound. Unplugging and replugging
> the pedal and sustain switch jacks seemed to clear up the problem.

...

One of the most common reasons for this sort of behaviour is the 'reset
level' ("DC OK Threshhold") on the power supply. Over time the power
supply will age - and so it would not be unexpected that an adjustment
would be required, especially if it has been well used for many years.

If this level is a little low, it will most often manifest with some/all
of the LEDs being stuck on and the machine not working.

If this is the source of the problem, then it is something easy to
address (and is covered in the Service Manual, ref: Section 6 -
Adjustments and Checkout) [The service manual is available in both in
PDF form as well as through web page form at
http://www.rhodeschroma.com/?id=polaris ]

The whole manual is good to have - but if you don't want to download the
large file, here's the two para.'s that deal with the DC OK setting:

===================

DC OK THRESHOLD:
---------------

The factory setting for the DC OK threshold requires the use of a rather
elaborate test circuit; however, it is sufficient in the field to simply
back off on R17 to minimum (full CCW), then turn it clockwise until LED
CR10 lights. The nominal DC level out at DC OK (P3 pin 1, brown wire)
is +3V.

Late serial numbers use a different secondary board with a modified DC
OK circuit. ON these no adjustment is necessary or provided. The
nomimal DC level out at DC OK (P34 pin 1, brown wire) is +5V.

===================

Here's the link to the Adjustments section alone:

http://www.rhodeschroma.com/?id=polarisserviceadjustmentscheckout

Beyond the DC OK setting, it would also be recommended to go through the
full Adjustments and Checkout section - which will also confirm such
items as the DAC null - and will also ensure that the volume levels are
set up and memory is restored.

> I tried doing the adjustments listed on page 108 of the manual.
> But there is a problem with those directions. They instruct
> you to "turn the MASTER slider all the way up", and
> then to & quot;raise the MASTER slider until you
> hear the note just begin to bleed through". I don't
> understand how you can raise the slider any more after
> it is "all the way up".

The reference to Page 108 appears to be for the "Volume Offset"
adjustment in the User's Manual.

The text for this setting in the Service Manual is more clear:

http://www.rhodeschroma.com/?id=polarisserviceadjustmentscheckout#volumeoffset

Yea, I can attest to setting the DC OK by calibrating the power supply. My polaris would regularly freeze after being on for about 10 mins then sometimes I would lose sounds and the voices would dissapear. I got out my DVM the other day and decided I'm gonna give it a shot, and it was pretty easy to calibrate. My board was the early model, and apparently the calibration is different between the early and late so you have to identify which you have. On the early there are 3 adjustments, and it looks like there are no places to measure but then realized I could put my DVM probes into the back of the white connectors (where the wires go in, touching the copper pins)between the power board and the main board. Which wires to use are outlined in the service manual. I did the first two for analog voltages, and the dc ok last. There is a red LED for the dc ok calibration, and to calibrate you turn the dc ok trimmer all the way CCW, then slowly bring the trimmer right until the LED goes on. That was it, I had to turn mine a little past when the LED went on, but I think the trimmer was dirty as the voltage jumped around and wouldn't quite go to 3v.

All I can say is I've had it on for whole days and it doesn't even freeze at all anymore. My problem was getting really bad but now I've been able to get way more into this synth because I can rely on it now.

--- In chromapolaris@yahoogroups.com, "David Clarke" <ac151@...> wrote:
>
> > When I turned it on again, all the panel LEDs lit
> > and there was no sound. Unplugging and replugging
> > the pedal and sustain switch jacks seemed to clear up the problem.
> ...
>
> One of the most common reasons for this sort of behaviour is the 'reset
> level' ("DC OK Threshhold") on the power supply. Over time the power
> supply will age - and so it would not be unexpected that an adjustment
> would be required, especially if it has been well used for many years.
>
> If this level is a little low, it will most often manifest with some/all
> of the LEDs being stuck on and the machine not working.
>
> If this is the source of the problem, then it is something easy to
> address (and is covered in the Service Manual, ref: Section 6 -
> Adjustments and Checkout) [The service manual is available in both in
> PDF form as well as through web page form at
> http://www.rhodeschroma.com/?id=polaris ]
>
> The whole manual is good to have - but if you don't want to download the
> large file, here's the two para.'s that deal with the DC OK setting:
>
> ===================
>
> DC OK THRESHOLD:
> ---------------
>
> The factory setting for the DC OK threshold requires the use of a rather
> elaborate test circuit; however, it is sufficient in the field to simply
> back off on R17 to minimum (full CCW), then turn it clockwise until LED
> CR10 lights. The nominal DC level out at DC OK (P3 pin 1, brown wire)
> is +3V.
>
> Late serial numbers use a different secondary board with a modified DC
> OK circuit. ON these no adjustment is necessary or provided. The
> nomimal DC level out at DC OK (P34 pin 1, brown wire) is +5V.
>
> ===================
>
> Here's the link to the Adjustments section alone:
>
> http://www.rhodeschroma.com/?id=polarisserviceadjustmentscheckout
>
> Beyond the DC OK setting, it would also be recommended to go through the
> full Adjustments and Checkout section - which will also confirm such
> items as the DAC null - and will also ensure that the volume levels are
> set up and memory is restored.
>
> > I tried doing the adjustments listed on page 108 of the manual.
> > But there is a problem with those directions. They instruct
> > you to "turn the MASTER slider all the way up", and
> > then to & quot;raise the MASTER slider until you
> > hear the note just begin to bleed through". I don't
> > understand how you can raise the slider any more after
> > it is "all the way up".
>
> The reference to Page 108 appears to be for the "Volume Offset"
> adjustment in the User's Manual.
>
> The text for this setting in the Service Manual is more clear:
>
> http://www.rhodeschroma.com/?id=polarisserviceadjustmentscheckout#volumeoffset
>