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ChromaTalk Archives: May 2012

Polaris sliders

John Leimseider [21030434++]

See thread Slider caps wanted, April 2012

I found my box of Polaris slide pots. These are the later version, the ones that don't break when you accidentally use one… Please note that on the earlier boards, you need to clip the 4 mounting tabs from these pots. On later boards, there are already holes on the board for them. You can't drill holes on the old boards so you have to clip the legs!!!

Yes, it's a hassle. If anyone wants them, it's $100 for the set of 20, plus shipping. I guess it's $10 for shipping in Canada, $20 for the US. Anywhere else, I'll have to check as needed. Please let me know if you want some. You can Email me at [address removed]. Thanks!

new serial number

Richard Sales [21030644]

Add 21030644 to your data base!

Got my Chroma finally - covered in gooey, gross devil's food cake foam rot. Picked it up in the Bay Area a couple weeks ago. Cleaned off with alcohol and Goo Gone. Turned it on, a fan like noise for a minute... then it croaked. Has an interesting document with it about the Chroma Cult with a list of names of Chroma Cult folks. Has anyone seen that? Cooper MIDI Chromaface and Syntech MIDI. I assume I won't need it with the CC+ mod.

When I can get to the mainland I'll take it to Rick Smith (Vancouver B.C.) for restoration. Could be a while as I'm just finishing renovation of my studio which started mid February and I'm pretty backed up with work.

Also got another Chroma Polaris. Out of the two I now own, I'm hoping to have ONE that works. I know about the rewiring the brittle ribbon trick. I'm sure that's what's wrong.

Anyhow, happy to be an official member of the club! Soon enough, I will start flooding you with extraordinarily stupid questions.

You've been warned!!!

Jesper Ödemark [21010135]

Congrat's on the Chroma!

I bet a good tech and some help from the list will get her back into shape. With some luck it's "just" the lousy PSU.

David Clarke [21030085++]

... Turned it on, a fan like noise for a minute... then it croaked.

Notwithstanding what previous owners might have installed, a fan modification was available from the factory for the Chromas.

That unit hooked directly up to the 117vac power (after the fuse and switch), and so if it was this fan that was installed - then it stopping may have just been the fuse blowing.

If it is the original power supply, and nothing has been done to it recently - then just as Jesper noted, it may just need some power supply TLC.

Also (if not already done) a quick review of the CPU board is likely in order - to see if batteries were left inside and if they have leaked. (If there's significant battery damage on the CPU board, then it is unlikely the keyboard can power-up as-is.)

Has an interesting document with it about the Chroma Cult with a list of names of Chroma Cult folks. Has anyone seen that?

Is it the list seen here: Chroma Cult Patch Credits, or something different?

Cooper MIDI Chromaface and Syntech MIDI. I assume I won't need it with the CC+ mod.

Correct. You could still use them with the CC+ (if you really wanted), but as you have the MIDI kit for the CC+, there's really no functional need to have the other interfaces.

Also got another Chroma Polaris. Out of the two I now own, I'm hoping to have ONE that works. I know about the rewiring the brittle ribbon trick. I'm sure that's what's wrong.

While ribbon fixes can often help things work for a while, as of February this year Paul DeRocco [21030230] has full replacement panels available, so the membrane woes can be a thing of the past.

Best regards,

David Clarke

Richard Sales [21030644]

Thanks Jesper and David!!!

I wrote Paul about the membrane panel. Looks like an easy enough repair.

Yes, the Chroma Cult document is the same!

Hopefully in a week or two I can open up the Chroma and start the long process of restoring the Lost, Buried in Lava City of Pompeii (Chroma).

If I can get it to power up, I might brave some of the repairs myself, although I usually - and most likely will - leave that to a technician.

Jesper Ödemark [21010135]

Nothing wrong with a good tech - on the contrary! But with these old delicate instruments it is always worth at least a visual inspection. Even the most unskilled hometech can change a fuse (if it's socketed), see if there is serious battery leakage and also notice if all voice cards are in place, card connectors in place etc. If nothing else, it sure saves time in trouble shooting.

Keep us posted, we all want to see another phoenix rise from the ashes of its former self! :D

Slightly OT: Kurzweil Midiboard for sale

RJ Krohn [21030455]

hey folks, hope this doesnt step on anyone's toes: the only reason i'm posting this here is that folks seem to be abnormally into poly AT-i know i am-thus, i figured i'd float it here. I've got a rev 1 midiboard in good working condition, you can see the pics here:

[craigslist URL removed]

i'd be willing to move on the price somewhat. especially if it's a local sale. let me know if any of you are interested; playing the chroma from the midiboard is prettty nice, as you can add synths and such. thanks, rj

FS: Chroma 21010104

Jesper Ödemark [21010135]

35000 SEK, found on Facebook. Already in the registry and not mine. Just wanted to pass the info to anyone in the nordic region interested...

Let me know if you want his details (unless he posts it here soon by himself).

Chroma 21030552 For Sale

Dave Blees [21030552]

Tomorrow, May 10th will mark the 29th anniversary of buying my Chroma. It's been a long, strange trip to be sure, but all good things... etc., etc....

I guess that in addition to finally having the opportunity for a real summer vacation for a change this year, I am also being reminded of the big downside of unemployment - I need to rustle up some dough! So to that end, I am beginning my big liquidation project by peddling my best piece of all, which has sadly seen shamefully little use in recent years, and needs a good home anyway. I'll be having some lesser gear available soon, but may be hard-pressed to part with the Polaris...

Chris Ryan [21030691] has been kind enough to put up a Classified Ad on RhodesChroma.com, which links to an article page with the full details. (Thanks, Chris!) I'd really like to find an appreciative buyer without having to give ebay a cut!

Hans Wurrrst

hi dave,

what is the price you're asking for it?

thanks

Dave Blees [21030552]

Kris - Since the only working Chroma I've seen for sale in quite some time is the one that's been on ebay [21030379; see Chroma 21030379 on eBay, April] for a "Buy It Now" price of $4999 USD, and considering the quite superior condition of my unit, I'll have to see how an asking price of $5000 will fly... although of course any reasonable offer will be noted and considered. At this point, I am not desperate for a quick sale, but as you may guess, that is certainly subject to change!

(Comments or suggestions from the group are welcome!)

Chris Ryan [21030691]

I've tracked sale prices for the last few years: see the Price History.

Go to next message in thread, June 2012

Chroma on eBay

Chris Ryan [21030691]

Item #190676441245, ends May 13, current bid USD$10.00, reserve not met; "buy it now" for USD$3,800.00. From the description: "Model #2103. [I've asked for the serial number.] This baby is in great, fully functional condition. It has just been carefully gone through by our local Chroma aces, The Good Guys, and nit-picked to near perfection. Even looks good! [He writes "Pictures should be up by Wednesday afternoon" but they're not up as of this writing.] Auction includes the original Anvil case, but as is typical, the foam has rotted over the years—I will pack it with replacement padding. Also comes with the original pedal and manual. I don't know it's full history, but the guy I bought it from kept it in his studio, little-played, for years. I have owned it two years, and also kept it inside and mostly unplayed. It looks and plays like it's had an easy life, that's for sure. No MIDI interface is included."

Chris Ryan [21030691]

This is Chroma 21030626, new to the registry.

Dave Blees [21030552]

weird.... before you say anything, my mistake! I could swear I just now saw an email saying that mpkearns' unit was sold, but it's past my bedtime... heh - never mind...

g'nite!

Chris Ryan [21030691]

Sold for USD$3,500.00.

Silent Chroma

John Monforte

Hello All,

I am a tech working on a deeply troubled Chroma. I have fixed the power supply and CPU so far, among other things.

I can't get a sound out of it. Checking the individual voice outputs (Z10 on the cards) also shows no signal.

The instrument will boot with "1." in the top display and "01234567" in the data window no matter how many voice cards I have plugged in at the time.

A warm boot (SS50), running the diagnostic (SS31) does nothing either.

I know the keyboard is being read, since I can set the split point on any key. The power supplies are running cool and providing good voltages.

Any ideas?

Luca Sasdelli [21010226]

Hello John,

the "01234567" means that no voices are passing auto-tuning, therefore the instrument doesn't sound. You should investigate within the DAC on I/O board, to see if it does correct control voltage to the Channel Motherboard.

Still on CMB, Z20 is the Zero Crossing Detector, so while the voice cards are tested, it should present some square waveform on its output: Z20's task is to sample oscillator waveforms to be feed to the I/O board for period measure.

Does the instrument use the original CPU board or the CC+? Does the PSU provide the proper reset circuitry for power-on reset?

Cheers
Luca

John Monforte

Hi Luca,

Thanks for your quick reply to my problem.

I didn't mention that the auto tuning appears to be functional, but obviously can't tune a waveform that is not present. Even if I use SS31 which defeats the muting, I get no sound.

In case it is important, the data display does not have an "E" with the numbers.

This unit has an original processor board. It appears to cold boot just fine and again when I do an SS50 warm boot it gives the same behavior.

I also tried running only one voice card - in case one of them is jamming up the rest of them. I get the same data display and still no sound.

I'm not sure what to try next.

Kind Regards,
John

Paul DeRocco [21030230]

Check anything that's common to all channels. First place I'd look is at the DAC, and then at the data bus that goes from the I/O board down to the channel motherboard.

In case it is important, the data display does not have an "E" with the numbers.

No, the eighth digit overwrites the E.

New owner introduction; interest in Test Controller PCBs/stripboard layouts

Adrian [21040017]

Hello list members,

I'm the proud new owner of a Chroma; finally! What an amazing community, and Chris' web site is nothing short of incredible.

Did anything come of the Voice Board Test Controller PCB project discussed a few months ago on the list? I would love to obtain one if possible - my Chroma apparently has a faulty voice board (I say apparently because I haven't actually taken delivery of it yet!)

Alternatively, I'm happy to make my own stripboards if the PCBs aren't available. Are the stripboard layouts available? I can't seem to find them on this page: Test Controller.

Cheers & Thanks,

Luca Sasdelli [21010226]

Hello Adrian,

the Test Controller I've built doesn't has a PCB indeed; I've started to design one, to be shared with other list members along with a suitable box front panel, both quite expensive items, on which some quantity discounts are available.

Stripboards are available from near all electronic parts suppliers; of course they require lots of hand wire cablings and are prone to every sort of mistakes.

I can't promise any timeline for the Test Controller PCB design, but I should do anyway (maybe during next summertime).

Paul DeRocco [21030230]

I'm the proud new owner of a Chroma; finally! What an amazing community, and Chris' web site is nothing short of incredible.

Welcome to the club. I hope you enjoy your new instrument.

Did anything come of the Voice Board Test Controller PCB project discussed a few months ago on the list? I would love to obtain one if possible - my Chroma apparently has a faulty voice board (I say apparently because I haven't actually taken delivery of it yet!)

The tester sounds like a good idea for a service shop that may have to test a lot of boards. But if you've only got one bad board, it will be a lot less work and expense just to debug it the old-fashioned way. It's usually not that hard. If you remove the good boards, you can put the bad board into a slot where you can easily probe it. In my units, the failures were all either dried out electrolytics in the VCF circuits which prevented them from self-oscillating, and burned out CMOS logic chips. Other people will have seen other failure patterns which they can tell you about here.

Faulty voice

David Hobson [21030506]

Hello,

I replaced my cpu with the cc+ and things are better...However, When I tune the voices they all tune except for voice 1 which is not turned off but plays in the out of tune state. Could this be a problem with the old power supply? I can still play it as a 7 voice machine if I take number 1 out. Let me know what you think.

Brian McCully [21030361]

Get the new power supply. Regardless. It's TOTALLY worth the no-hum.

Re-seat the card, swap it around, find some extra cards to stick in there. It's a Chroma - like every other old mechanical beast out there, they sometimes get cranky. Like me (an old bio-mechanical beast). Sometimes things just don't work that well, and then ... they do. And then you forget there was a problem. have fun, -Brian

Paul DeRocco [21030230]

I replaced my cpu with the cc+ and things are better...However, When I tune the voices they all tune except for voice 1 which is not turned off but plays in the out of tune state. Could this be a problem with the old power supply?

Unlikely. It's probably a leaky sample-and-hold in one of the pitch channels, if it gets through the auto-tune but tunes improperly. It could be one of the 4051 CMOS switches Z19 or Z20, or one of the TL082 dual op-amps Z21 or Z23, or even one of the capacitors C24, C28, C32 or C36.

David Hobson [21030506]

Hello,

Thanks for the replies,

I am admittedly a technophobe..I don't know my z19 from my tl082, but I do have extra voice cards...so I'll begin by trying to swap voice cards...the rest i'll have to see my repairman for.

Thanks, David Hobson

Google Doodle :)

Luca Sasdelli [21010226]

www.google.com :)

Google did an interactive "doodle" for Bob Moog's 78th birthday. Here's a screen shot. See Robert Moog's 78th Birthday to play with the widget.

Goog

Rafael Grandek [21010205]

i like!

Chris Smalt [21010280+]

Ahhhhh, doesn't work on my Safari, Firefox or TenFourFox. Not on iPhone either.

Chris (always trails by one or two OS versions)

Jesper Ödemark [21010135]

Works well om my firefox, with recording and everything. But there's some boxes to cross/uncross regarding the script. SOmeone more techie can probably make that more understandable. :D

Programming Manual on eBay

Chris Ryan [21030691]

Item #150822476840, starting bid USD$0.99, no bids yet, ends May 25. This Programming Manual has a more generic, apparently paper cover, without the photo; I have a vague recollection I've seen this before but I'm not sure what it means: a draft? The description says "this is NOT a copy it is the ORIGINAL manual that came with the unit." I've asked the seller.

Picture from the auction:

eBay150822476840

Chris Ryan [21030691]

Sold—to me—for USD$2.36. The seller replied to me, "This is a rare Preliminary copy, it is noted on the inside second page that a more complete revised edition will be released and how to order one. This one also has the following print, CBS, Inc. [1982] programming Manual Revision 1 for Chroma Software Revision 10-April 14, 1982." Of course, the Programming Manual that most of us have, with the glossy cover with photograph, notes inside that it is a "preliminary copy." The blurb is reproduced on the site, along with a note from Steve Grom of Fender, who wrote to me a few years back, "I don't think I even saw a rough draft of the second programming manual, but we did talk about it. There were other more pressing issues." At any rate, I figured at that price it would be interesting to acquire and see if there are any differences.

Arun Majumdar [21030348]

I would be interested in knowing about this too!! Thanks :)

Go to next message in thread, June 2012

I hope this is not a stupid question...I have already reached my limit.

David Hobson [21030506]

Hello,

I am wondering if anyone can tell me if there is an individual program dump to sysex...I read all I could on the rhodes site , but to no avail.

Any help is appreciated.

David Clarke [21030085++]

If you are using the CC+, then there is both the ability to request a single program via SYSEX (to have that program then sent to you via SYSEX) as well as the ability to use a panel-key sequence to have the current program sent via sysex.

The former is discussed here: The Chroma CPU Plus (CC+): User's Guide - MIDI System Exclusive (SysEx).

(Single Program Dump/Single Program Dump Request)

The latter is discussed here: The Chroma CPU Plus (CC+): User's Guide - Set Split 20 Send Program 0 over the MIDI Interface.

David Hobson [21030506]

Thank you for taking the time to answer my question.

Rhodes Chroma in Local Store

Michael Zacherl [21030253]

Hi,

just got notice of this Chroma in a local store: Rhodes ( ARP ) Chroma FOR SALE

I'm trying to find out the serial#, but have only little (i.e. no) time at hands.

Michael Zacherl [21030253]

Hi again Chris et al,

according to an email I just got from this shop below this particular Chroma's serial# is Y21010037.

I just looked up the registry, it appears to be a new entry (leaving the 'Y' of course).

Go to next message in thread, June 2012