Rhodes Chroma Polaris

I have a Polaris that has seemingly seized up completely?
Basically it powers on with about half the leds remaining lit.
None of the push buttons are operational nor any of the keys.
Other than powering on absolutely nothing is functional!
It is also producing an awful sustained noise. Any ideas?

> From: charlespjackson
>
> I have a Polaris that has seemingly seized up completely?
> Basically it powers on with about half the leds remaining lit.
> None of the push buttons are operational nor any of the keys.
> Other than powering on absolutely nothing is functional!
> It is also producing an awful sustained noise. Any ideas?

The computer is crashed, so nothing is initialized. The LEDs power up in a
random state, and the analog circuits have random control voltages on them.
The only conceivable "dumb" fix would be to unplug an replug all socketed
chips in the vicinity of the CPU. I don't remember if the CMOS RAM chips are
socketed, but if they are, first remove the battery (and be aware that
you'll lose the stored programs and calibrations). Other than that, there's
no alternative but to have a technician open the thing up and debug it with
a scope.

--

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

--- In chromapolaris@yahoogroups.com, "charlespjackson"
<charlespjackson@...> wrote:

>
> I have a Polaris that has seemingly seized up completely?
> Basically it powers on with about half the leds remaining lit.
> None of the push buttons are operational nor any of the keys.
> Other than powering on absolutely nothing is functional!
> It is also producing an awful sustained noise. Any ideas?
>

You can try the NASA approach-- repeatedly power cycle (as many as 50
imes) waiting different amounts of time between cycles to if the CPU
boots.

I've never seen your exact problem, but on one of my polaris the
power supply was failing or the reset logic was bad and it would lock
with all lights on and freeze about 50% of the time, more if it was
sitting unused for a few days.

-Ben

> ... I have a Polaris that has seemingly seized
> up completely? Basically it powers on with about
> half the leds remaining lit...

Following up to the responses of others, this can also occur because of
the 'reset level' adjustment ("DC OK Threshhold") on the power supply
being incorrect.

Specifically, it could be a little low, causing the CPU to wake up
before it should. 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 PDF form at
http://www.rhodeschroma.com/?id=polaris ]

> From: David Clarke
>
> Following up to the responses of others, this can also occur because of
> the 'reset level' adjustment ("DC OK Threshhold") on the power supply
> being incorrect.
>
> Specifically, it could be a little low, causing the CPU to wake up
> before it should. 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 PDF form at
> http://www.rhodeschroma.com/?id=polaris ]

Good point--forgot about that. It could also be too high, causing the CPU
not to start up. The reset line doesn't hold the LEDs off, or zero the
analog control voltages.

--

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

--- In chromapolaris@yahoogroups.com, "David Clarke" <ac151@...> wrote:

>
> > ... I have a Polaris that has seemingly seized
> > up completely? Basically it powers on with about
> > half the leds remaining lit...
>
> Following up to the responses of others, this can also occur because of
> the 'reset level' adjustment ("DC OK Threshhold") on the power supply
> being incorrect.
>
> Specifically, it could be a little low, causing the CPU to wake up
> before it should. 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 PDF form at
> http://www.rhodeschroma.com/?id=polaris ]
>

Excellent News! Problem had been fixed and quite easily I must add
thanks to the recommendation provided above.
This was indeed exactly the issue. I simply had to perform a minor
adjustment to the R17 pot. Thank you all very much for the insight
and advice.