Rhodes Chroma Polaris

i was playing a gig--had my Polaris set up, it worked in the sound check fine-- then turned it off--- turned it on before our set was to start and the Polaris  turned on with 90% of the led's on--and no sound , and was unresponsive to all buttons.   i turned it on and off and no change.   so gave up playing it for the set--
packing up after the show i plugged it in again and it seemed to light up normally ,
but i wasnt able to experiment playing it at that time--
now  a day later, i set it up again --turned it on and have the same  unresponsive  LEDs on  status,   and still wont play or respond to controls.  the LED 's  almost all on is  very abnormal.
.   this is very odd--  [ the polaris has replacement  membrane switch panels]  --  i have no idea what is going on.at this time-- ive had it for years  and this has never happenned.  

> From: wasteking1@...
>
> i was playing a gig--had my Polaris set up, it worked in the
> sound check fine-- then turned it off--- turned it on before
> our set was to start and the Polaris turned on with 90% of
> the led's on--and no sound , and was unresponsive to all
> buttons. i turned it on and off and no change. so gave up
> playing it for the set--
> packing up after the show i plugged it in again and it seemed
> to light up normally ,
> but i wasnt able to experiment playing it at that time--
> now a day later, i set it up again --turned it on and have
> the same unresponsive LEDs on status, and still wont
> play or respond to controls. the LED 's almost all on is
> very abnormal.

When you're looking for your keys, the first place to look is under the streetlight. If you have the earlier version power supply, it's possible that the DC OK threshold is set too close to 5V, and sometimes the processor is being held in reset. There's an LED on the power supply that turns on when the power supply releases the reset line to the processor, so if that stays off, then that's the problem.

There are plenty of other possible causes. In a very old instrument like this, the EPROMs could be fading, and the computer crashing, meaning the EPROMs should be reprogrammed. But that would be just as likely to happen in the middle of playing. The fact that it only happens or doesn't happen when you turn it on smells like the power supply adjustment.

--

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

is that LED you describe the one labeled cr-10 on the secondary board?  it stays off ----
meanwhile , ive turned the unit on a few times over the last few days and it stays unresponsive with over 30 of the LED's on in kind of a random pattern.
what would you suggest ?
--ive fixed a few things on my polaris before and replaced the membrane switch panels---   the thing sounds damn awesome--- and i have a number of other synths--- this has such a wonderful tone. 


(also-- for your information  i had this polaris on  a two tiered rack with a DSI polyevolver which was  connected to a slaved polyevolver rack----all on one power strip------ now the Polyevolvers  are acting weird with the sounds being corrupted  in the memory of one or both units--- they were identically programmed  before the gig. Now they sound different with the same  patch names/numbers  on the screen.    Im trying to contact DSI about this problem ...........   i wonder if some thing happened with the power that night at the club--  i now have 2 messed up synths).

> From: wasteking1@...
>
> is that LED you describe the one labeled cr-10 on the
> secondary board? it stays off ----
> meanwhile , ive turned the unit on a few times over the last
> few days and it stays unresponsive with over 30 of the LED's
> on in kind of a random pattern.
> what would you suggest ?

Yes, that LED should be on. If it's off, either the 5V digital supply is too low, because the supply itself is maladjusted or because there's some unusually high load on it, or the DC OK adjustment is off. That's the comparator that holds the processor reset until the supply comes up to 4.8V or so.

If you have a meter, it's good idea to measure the supply first. That would be the voltage between P3-2 and P3-3, the red and green wires on the 4-conductor cable from the supply to the main board. If it's not within 4.95 to 5.05, adjust trimpot R9. If you can't get it in range, there's a bigger problem somewhere. Most likely, though, trimpot R12 near the LED is maladjusted. Turn it until the light comes on, and then go another 10 degrees or so. Or if you have a meter, adjust the digital 5V supply to 4.8V, adjust the trimpot to right where the light comes on, then readjust the 5V to the correct voltage.

--

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

we are onto something here----
i turned R17  trimpot  clockwise  about 45 degrees clockwise  and the led went on-- the control panel returned to normal Led patterns----  i went another 10 degrees and now when i start it up it flashes the  bulk of the Leds  once ,   and then stabilizes with the normal  ON pattern , and controls work and the unit plays normally (so it seems) . --  i then measured the voltage  as you described --it was maybe 4.8v    so i turned  R9 up till it neared 5v ,  then i was able to turn R17 down  some --
now  the same '10degrees past Led lighting up '   was an increase of only about 30 degrees of clockwise  rotation .  is there a 'balance between these trim pots?  can they be set too high?  or is it 'fine'.....

Does this mean the transformer or another part of the power supply system is damaged?  it seems like  a big adjustment since it was fine a half hour before and my other keyboard that was plugged in at the same time thru the same power strip   ( a DSI Polyevolver) seems to have has some  memory corruption that seems like some internal electronic damage and the factory tech guy has suggested i send it in to them for repairs.

thank you so much because this seems be solving the recent Polaris crisis-------  

> From: wasteking1@...
>
> we are onto something here----
> i turned R17 trimpot clockwise about 45 degrees clockwise
> and the led went on-- the control panel returned to normal
> Led patterns---- i went another 10 degrees and now when i
> start it up it flashes the bulk of the Leds once , and
> then stabilizes with the normal ON pattern , and controls
> work and the unit plays normally (so it seems) . -- i then
> measured the voltage as you described --it was maybe 4.8v
> so i turned R9 up till it neared 5v , then i was able to
> turn R17 down some --
> now the same '10degrees past Led lighting up ' was an
> increase of only about 30 degrees of clockwise rotation .
> is there a 'balance between these trim pots? can they be set
> too high? or is it 'fine'.....

One sets the voltage, the other sets the threshold at which the CPU is allowed to operate. The ideal, as I said, is for the DC OK line to turn on when the supply is about 4.8V. The easiest way to do that is to use the other trimmer to set the voltage to 4.8V, adjust the DC OK trimmer to the point where the light just turns on, then set the voltage to 5V. That will give you 0.2V of margin.

> Does this mean the transformer or another part of the power
> supply system is damaged? it seems like a big adjustment
> since it was fine a half hour before and my other keyboard
> that was plugged in at the same time thru the same power
> strip ( a DSI Polyevolver) seems to have has some memory
> corruption that seems like some internal electronic damage
> and the factory tech guy has suggested i send it in to them
> for repairs.

The transformer is unlikely to be bothered by much of anything. It's possible a power surge damaged something, but it's also possible that years of very slow drift just happened to reach the threshold at the same time something unrelated happened to your other instrument.

--

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