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ChromaTalk Archives: September 2007

Polaris RAM IC Types

Chris Ryan [21030691]

New on the site this month is a write-up by Gregory Ryan Freer on Polaris RAM IC Types, which includes an overview of RAM upgrades for the instrument along with installation instructions from Fender.

David Clarke [21030085++]

As an aside, the general topic of RAM expansion and the content of the memory expansion packages is discussed in Section 7 (Options) of the Polaris Service Manual.

Also, the write-up notes "...the expansion kits were specific only to increasing the sequencer's ability to record longer songs and more of them. So those of us who had also hoped to increase the patch storage capacity...were SOL..."

It is certainly true that the expansion packages only offer more RAM (and no 'feature' updates) but insofar as I know the memory allocation in the Polaris is shared, so both programs and sequences draw upon the same pool of RAM. This means that for a given number of sequences you may actually get 'more' or 'less' programs (depending on how much RAM is installed) but the total number of programs won't exceed 132.

keyboard stand

Ray Hannisian [21030829]

I've had my Chroma since the early 80's. Now, for the first time, I want to put it on a portable tubular, metal keyboard stand. Can anyone recommend an appropriate brand or model?

Thank you.

Chris Ryan [21030691]

There was a bit of discussion about this last year. See the thread "Chroma Spotting (Herbie Hancock)" from February 2006; I included photos of a very sturdy stand I use for my Chroma.

Jeff Bova [21030407++]

Check out Quick Lok stands.

They have a couple of different versions of this style stand.

Jeff Bova [21030407++]

Here's one I use with my heavier instruments, very stable and folds up compactly:

Donald Tillman

The Quicklock WS-550 is excellent. It's sturdy, the right size, folds up nicely, and looks good under a Chroma. I've used it for a decade with no complaints.

Jack Colburne [21030142+]


I think the WS-550 is a perfect stand for the beasts.

Jesper Ödemark [21010135]

Spring loaded stand locks and a 40 kilo Chroma sounds like a very bad idea indeed to me...

Fredo Fraile [21040011+]

Hallo, what is about a z formed mixerstand as musicstorekoeln offered for under 40 Euro, i use one and i think it looks really cool and elegant, look on there homepage for a picture, and it is build for heavy mixers up 70kg, ist was the best that i could find around here

Chroma SPSU kit

Luca Sasdelli [21010226]

Hi all,

due to the upcoming PSU leakage problems, Riccardo and me are working around a SPSU replacement kit. Our primary aim is the easy setup, in order to allow almost anybody to carry it out by his- or herself.

The original PSU connections are replicated in the identical way, so that a direct swap is made possible.

The kit is composed by the following parts:

  • a MeanWell SPSU
  • a PCB, original schematic by Sandro Sfregola, with the reset circuitry and +5V regulator
  • a mounting bracket for the SPSU
  • a spacing strip for the back panel
  • a power inlet plug with new cables
  • four spacers for PCB mounting
  • nuts and bolts as required

Kit installation overview

For easy reference, please see the Power Supply Assembly Schematic.


  1. disconnect any cable connected to the Chroma
  2. open the top cover
  3. on the original PSU, disconnect the four multiple connectors on the side near the wooden support and CLEARLY MARK them, to avoid errors in re-connecting them to the new PCB (they're named P1, P2, P3 and P4)
  4. with clips and/or pliers, cut cables from the power plug, all cables going to the transformer and to the big capacitor C3 on the PSU board
  5. unscrew all PSU board, starting with the 4 fixing the transformer, then the 3 screws holding the C3 capacitor and the remaining 2 screws within the connectors area. Save all screws for later use
  6. unscrew the back panel and carefully lift it away, in order to unscrew all screws securing it to the PSU board (ground pads and Q1, Q2, Q4, Q6, Q7, Q9 transistors)
  7. with a soldering iron (only one operation with it), unsolder the two pin of the Q1 transistor
  8. with great care and pay special attention to existing wiring on back panel, take off the PSU board
  9. unscrew and remove the power plug

The Chroma is now ready for the upgrade.


  1. fix the mounting bracket to the SPSU as per supplied drawing, using the supplied nuts and bolts
  2. connect the multiple wires to SPSU, respecting the color-coding as per supplied schematic
  3. install the SPSU + bracket on original transformer turrets, using the original screws
  4. install the PCB on the wooden Chroma basement, using the four spacers to allow a minimum of distance from it. Note: the PCB is mounted in contact with the basement, in order to protect it from breaks during connector insertion
  5. mount the new power plug on back panel
  6. connect power wires to AC marked terminals on SPSU, and the yellow/green ground wire to SPSU casing
  7. mount the spacing strip between back panel and basement, in replace to the original PCB
  8. insert the four connectors in the new PCB, respecting the original position and marking (P1 to P4)
  9. reconnect all green ground cables to frame as appropriate

Now the upgrade procedure is completed.

Power on the instrument, check that the LED on PSU PCB should lit, check that the Chroma boot-up routine goes on properly, and then check the +5V with a multimeter, adjusting the trimmer on new PCB as required, see How to Swap the Power Supply.

How much does it cost?

The more expensive components in this project are the PCB mastering and PLC programming for metal cut. Therefore, we need to know an average number of potential requeters, in order to distribute those cost over - hopefully - the largest base possible, thus lowering them.

The kit cost would be between 100,00 and 130,00 euros, including shipping (this DOES NOT include additional customs costs). It will be also possible to order it without the MeanWell PSU, with 36,00 euros saving.

Awaiting you comments, folks! ;-)

Luca and Riccardo

Mal Meehan [21010182++]

Hi Luca

I would be interested in one, put me on your list.

Rob Belcher [16330123]

Likely me too Sandro, put me down. I assume it will fit in the Chroma Expander too?

Luca Sasdelli [21010226]

Hi Rob,

the SPSU kit it designed to completely replace the original PSU PCB, that is identical both in Chroma and Expander.

Riccardo own a couple of expanders, therefore I guess that he can test the mechanical installation in there, just to be sure that no exceptions are occurring.

BTW, the SPSU and new PCB size are very smaller than the PSU PCB, so there should be any mounting problems.

Lars Johansson [21030632]

I'll take one too !

Åke Danielson [21010068]

Hi Luca,

Good idea! I would like to order one.

Bob Brenenstuhl [21030894]

Would this work in the U.S.? If not are there any plans to make one that would?

Luca Sasdelli [21010226]

Hi Bob,

the MeanWell T-60 AC input rating goes from 85V to 264V, both 50 and 60Hz, so there are no compatibility issues at all.

Robert Shanks [21030301]


Thank you for your hard work. I want one, too.

Rob Vandivier [21030396]

count me in

Robert Kastler [21030157]

Hi Luca & all,

Sorry for my ignorance, but my (CC+ tuned) Chroma's original PSU is working perfectly fine so far, so I am unsure whether it makes sense to invest in a spare one at the moment - are the leakage problems you're talking about likely to happen with the original PSUs in the (near) future ?

Thanks for your efforts

Luca Sasdelli [21010226]

Hi Robert,

no reason to replace something that works right well :-) Anyway, the advantages in replacing the original PSU are still the ones you find on Chroma website: 3kg less weight, no more buzz, no stray magnetic fields from the Chroma, no heating inside.

Rob Vandivier [21030396]

preventative measure only if present psu alreadfy works ok.

Jesper Ödemark [21010135]

Sorry for my ignorance, but my (CC+ tuned) Chroma's original PSU is working perfectly fine so far, so I am unsure whether it makes sense to invest in a spare one at the moment - are the leakage problems you're talking about likely to happen with the original PSUs in the (near) future ?

Like me then... my PSU was serviced the year before I bought it but I haven't checked to see what has been changed. I'd rather not spend 100 euros+ if I won't need a new PSU in the near future...

Jesper Ödemark [21010135]

no reason to replace something that works right well :-) Anyway, the advantages in replacing the original PSU are still the ones you find on Chroma website: 3kg less weight, no more buzz, no stray magnetic fields from the Chroma, no heating inside.

So, it's basically the heat issue to have in mind then... there sure is a bit of oscillator drifting going on in mine...

Thomas Story [21030352]

I for one would love to end the buzzing from my Chroma. If the new power supply can eliminate the annoying buzz the count me in to buy one. That alone is reason enough for me.

Jesper Ödemark [21010135]

Mine isn't buzzing, that's why I'm not seeing that as a problem. :)

Mal Meehan [21010182++]

I had my power supply overhauled a few years back and it's been perfect but I would still be happy to have a spare PSU in the cupboard as I'm sure eventually somethings going to go wrong (It is a Chroma after all!).

Given that Chromas are reaching such high second hand prices I think 100-130 euros isn't that much to keep the unit going... I couldn't be without my Chroma, it's the main synth in my set-up (and I have 10+ other analogue vintage synths), and i would hate to be in the middle of something important and have it go down, especially as it's such a hassle to get someone to repair it!

Robert Kastler [21030157]

Thanks Luca & others,

No more buzz and heating combined with the precaution aspect is reason enough for me to buy one - so please count me in.

Thanks again for offering this to the group

Jesper Ödemark [21010135]

OK guys, you convinced me... write my name on the list too. Everything for the Chroma society... ;)

Enrico Dibennardo [21030494]

Ok count me in for unit too.

Claes von Heijne[16330008]

I would like to buy two replacement psu's, one for a Chroma, one for an Expander.

Brian Fifield [21030920]

Put me down for one too!

Go to next message in thread (October 2007)

For Sale: Chroma Syntech Midi Interface


Very good condition, works fine. [See MIDI Kits: Syntech/Chroma Cult/KMX.] Changed over to CC Plus. Can ship worldwide, $80 plus shipping (200 new). email: [e-mail address removed]

Dead Chroma

Bert Vermeulen

I have a dead chroma (only some leds are on). No blanking leds or display at start-up. I tried everything but i can't find the problem. If anybody have some suggestions please mail me. I think the problem is in the I/O board. I swap the I/O board with an other chroma. An other I/O board in this chroma works but this I/O board in the other chroma give the same problems. Power supply, voltages, reset are all ok. If i play a key i see an interrupt to the computerboard and i see changes in the Data lines.

At the I/O strobe decoder i see only at Z39 data signals. The IOWR (pin J10-2) is high and stay high (so Z40 and Z41 doesn't work and therefore led display eo also doesn't work.) At the computerboard i see no data at pin 6 of Z10.

It looks that the problem is in the computerboards but this board works fine if i swap the I/O board from an other. Or something in the I/O board lock the chroma but i cannot find it.

Chris Ryan [21030691]

Have you had a look at the Hardware Fault Diagnosis & Repair page at the site?

Bert Vermeulen

I checked everything at that list. This one has also a new PSU. But this chroma doesn't startup. It looks that something lock the unit during startup.

CC+ one more, please

Luca Pilla [21010218]

Hello! After some months, I'm returnig on Chromatalk with a new address email. Please, add also my name for the next batch of CC+.

Joe has left the building

Jesper Ödemark [21010135]

One of the old Chroma poster boys has left this globe of ours. Joe Zawinul passed away the 11th of September.

Jeff Bova [21030407++]

From Joe's site: "Joe Zawinul was born in Earth time on 07 July 1932 and was born in Eternity time on 11 September, 2007. He, and his music, will continue to inspire!"

Cool Blue patches on .wav or audio?

Richard Willoughby [21030348]

does anyone have a .wav or audio file for the Cool Blue patch bank that they would share? I'm still in JL Cooperland at this point and lack sysex capability.

Chris Ryan [21030691]

Have you tried the patch conversion tools?

Richard Willoughby [21030348]

I've tried opening those files a few times (running Windows XT) and have been unsuccessful. The computer just tells me that the "parameter" is incorrect when trying to open the specific file, after downloaded the Windowpatchtools. :(

David Clarke [21030085++]

Do you the error on attempting to run the patch tools themselves - or is the error seen after running the patch tools and attempting to use the resulting .snd file?

(I will e-mail you privately a .wav version of the file)

Richard Willoughby [21030348]

The error comes after attempting to initially run/open the program. I was never able to get as far as using the patchtools. I tried on 2 different computers, so I'm not quite sure what's going on.