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ChromaTalk Archives: September 2004

Cheap Chroma keys, woodwork, key contacts, output transformers, etc.

David Clarke [21030085++]

For anyone looking, there appears to be a semi complete Chroma chassis currently on Ebay: [Item 3745849436]

If anyone on the list gets this, please let us know the 8-digit serial number marked on it, so we can at least account for its whereabouts in the registry.

Here are the pictures:

Chris Ryan [21030691]

It's back on eBay--looks like the first bidder has a good chance of being the only one. Auction ends September 27. [Item 3749897885]

Wayne Griffin [16330111]

Is this evidence of a "chop" ?

Jesper Ödemark [21010135]

I saw that one last time too... if I was here in Europe I might have snatched it 'cause parts of my woodwork isn't that nice. And if it included the aftertouch "board" it would've been REALLY cool! ;)

I wonder what happened to the electronics...

Olli [21010284]

hi all,

actually, he sold the unit off piece by piece. i bought the CMB from him. i don't know, why he didn't sell the unit as a whole.... he would have made more out of it plus left a historic instument alife.

well...

Jack Colburne [21030142+]

Just spoke with the seller on the phone. He is pretty sure he has the cover (with the serial number) in storage and is going to pull it out too.

He also has the serial numbers for his own whole unit and one he sold previously. He said he'd forward all three numbers to Chris.

Chris Ryan [21030691]

Is this evidence of a "chop" ?

What is a "chop"?

Jack Colburne [21030142+]

What is a "chop"?

chop shop - a place where stolen cars are disassembled for their parts

Is this evidence of a "chop" ?

yes, technically. But, there's always more to the story than meets the eye. The seller is a Hammond Repair/Refurbisher/Sales/Doctor/Tech here in Massachusetts, USA. His main thing is to keep Hammonds (B3s, Model As, etc) and all kinds of Leslie speakers rebuilt and alive. And he seems to have a pretty healthy respect for the value of vintage instruments.

If I got the story right, he acquired the Chroma in question when he bought one of his whole units. He told me that the seller he bought it from basically threw it into the deal because it was in pretty bad shape. (I believe it... I got my second unit for almost literally pennies) He had sold another complete unit and tried some voice cards on line. They sold well and I figure that he figured people needed parts.

(He also mentioned that he had checked Chris' Chroma site to see if the ones he had acquired were reported stolen or not.)

Whatever the story, at least with all the units we'll never find simply because they ended up as parts for other units or in a dumpster, this is one we caught before it drifted into voltage-controlled-oblivion.

Jesper Ödemark [21010135]

"voltage controlled oblivion", I'll remember that phrase! :)

Music

Chris Ryan [21030691]

One of the things I've been working on for the new Chroma site is a music/discography section. A few people have commented over the years that, dedicated as it is to a musical instrument, the site is curiously silent. So this is a general call to send me any recordings (even highlights, e.g. solos) that you'd like to hear on the site, as long as they're legal to post.

I've made a small start on a discography, based on a quick Web search and some links from ChromaTalk subscribers and Registry entries. Please send at least:

  • Player name
  • Artist name (if different)
  • Name of recording
  • Label (plus catalogue number if available)
  • Year
  • Details (what tracks, particular solos, circumstances, etc.)
  • Any related URLs (artist, store, etc.)

I suppose tours would fit here as well. This is a fledgling effort and I'm sure it will evolve.

Chris Ryan [21030691]

Perhaps stating the obvious, but my intention was to include only Chroma-related audio and recordings!

Re: Picture of Syntech Retrofit

Go to first message in thread (August 2004)

Rob Johnson

Hey did you ever get a photo of the Syntech? If no I can probably take a shot of mine for you.

Chris Ryan [21030691]

Both Jack Colburne [21030142+] and Chris Now sent me excellent pictures--thanks.

Oscillator woes

Jimmy Moyer[21030184]

Hello Chroma analog circuit gods. (Sorry for being a pest while I try to fix this baby on my own.) Power supply now good [see Chroma power supply failed, August 2004], I've moved on to some voice cards failing the start-up tuning check. In the past my usual technique of narrowing it down to a few chips and replacing all of them has worked for me in the past. Not on this one.

By listening I can hear that the B channel is OK. The oscillator on the A channel is some 4.5 octaves too high in pitch and at a much lower volume. Filters and amps both OK.

Pitch A and Pitch B signals coming of the sample and hold look similar and move right as the keys change. By the time I get to the outputs of Z5 the A channel is screwed up - a ramp at the too high frequency and ramping from about -.7V up to 0. (B side OK with right frequency ramp from 0-5V)

I've tried replacing Z1, 2, 4, 5, but no change at all. Any suggestions?

Olli [21010284]

hi jimmy,

i have had some weird problems on my chroma not being able to identify the reason of different DCB problems until i found that one or more of the brown molex connectors had broken contacts inside.

generally, that is the first thing to check, but you might have done that already.

maybe that helps.

i suppose that you have tried swapping the DCBs to be sure its not the CMB.

good luck

Jimmy Moyer[21030184]

Both good advice, but not the trouble in this case. Definitely the DCB at fault. CMB is OK as good boards work in every slot and trouble follows this one.

I've had broken edge connectors before. These look physically OK and I checked continuity on all the pins. (Raises the thought that it would hurt for me to have a few of those brown connectors in my cache of parts. Anybody know exactly what they are? Still available?)

David Clarke [21030085++]

... By listening I can hear that the B channel is OK. The oscillator on the A channel is some 4.5 octaves too high in pitch and at a much lower volume. Filters and amps both OK. Pitch A and Pitch B signals coming of the sample and hold look similar and move right as the keys change.

By the time I get to the outputs of Z5 the A channel is screwed up a ramp at the too high frequency and ramping from about -.7V up to 0. (B side OK with right frequency ramp from 0-5V)

Considering the items already changed, you're now getting down to less-likely items.

That being the case I'd suggest, if you haven't done so already, to:

  1. Do a Set-Split 31 to leave all the boards enabled, and at their nominal settings. With this setting, check the output of the S/H for Pitch A on a 'good' board and Pitch A on a 'bad' board, looking both on the input and output sides of Z21 (pin 5 and 7).
  2. Confirm that you see similar voltage changes (at a reduced scale) at pin 4 of Z1 (should be scaled down version of Pitch A).
  3. Check the behaviour of CR1 (or just replace it, they're cheap and common).
  4. Confirm that none of the caps (e.g., C5, C3, C1) are shorted to ground.
  5. Confirm that nothing on the output side (e.g., nothing involving the sync line, etc.) is pulling the output down.

Good luck (and let us know how you make out!)

David Clarke [21030085++]

re: Oscillator woes (connector info)

re: voice card edge connectors:

...Raises the thought that it would hurt for me to have a few of those brown connectors in my cache of parts. Anybody know exactly what they are? Still available?

They're 8-pin, right-angle molex connectors, and are still available. The details are available from the archives in the "voicecard contacts" thread from December 2003.

In summary - Molex P/N 22-15-2086-P (avail. as Digikey P/N WM3006-ND) - should be about $1 ea.

Can someone ID the "Chroma MIDI Manual"?

David Clarke [21030085++]

Can anyone ID the Chroma MIDI Manual shown as part of the ebay listing below? [Item 3747180343]

(I didn't recognize which MIDI interface that manual goes with...)

Here's the picture.

Chris Ryan [21030691]

Since it says "Chroma MIDI Converter," I assume it is the Syntech [manual]. That's what mine is titled, although my first page is typewritten.

Jack Colburne [21030142+]

Yup. Looks like the Syntech version. I attached a scan of my manual's cover page. Including the extra staples. :)

The chroma is poorly represented on Harmony Central

Murray Macdonald [21030276+]

Hi Chromites,

Read this and weep.

http://www.harmony-central.com/Synth/Data/Chroma/Chroma-01.html

IM(ALY)HO, the Chroma is poorly represented.

Later this weekend I am going to set this right.

Alternate (updated) version of the Computer Interface Manual

David Clarke [21030085++]

I was poking around the Chroma site today and clicked on the link for the Interface Manual [PDF, 1.7mb].

My copy never had a front page - so I was interested to see what other pages I might be missing.

While flipping through I noticed that the body of my document and the one on the site didn't quite match.

Specifically, it looks like there is an alternate copy which is presumably newer, as it contains Polaris info (in addition to the Chroma data from the one on the site). Here are some other specific differences that I noted:

Section 1 (Introduction)

'Old' version (the one on the site) stops at "The interface view of the Expander." Other version has an additional 1/2 page or so entitled "The interface view of the Polaris."

Section 3/4

Section 3 of the old version is called "Command Descriptions" - but that is Section 4 of the other document, with Section 3 being 3 pages long entitled "Polaris Structure."

"Command Description Section"

New version seems to delete the comment on page 3-1 which starts off saying "...Any command that could conceivably "crash" the Chroma through misuse will not be allowed ..."

New version generally has a tag line for each of the opcodes to indicate what the Polaris will do in response to the specific opcode. (e.g., for "Tap Panel" we have:

Old Doc: "The panel tapper is triggered, unless it has been disabled."

New Doc: "The Chroma's panel tapper is triggered, unless it has been disabled. The Polaris ignored this."

The new doc has some polaris-only opcodes, such as:

  • Tune Get (16)
  • Tune Set (17 tt)
  • Open Object (18 oo oo mm)
  • Create Object (19 oooo nnnn mm)
  • Delete Object (1A)
  • Add Extension (1B)
  • Send Message (1C ss nn mm oo)
  • Get LED (1D nn)

"Software Requirements" Section

Some difference in text, and some different presentation of the flow shown in the "Interrupt Driver Dual Task Algorithm" pseudo code.

"Hardware Requirements" Section

The 'old' interface doc has both a "Minimal" and "Modified Minimal" circuit - the 'new' doc only has the "Modified Minimal" (but this is referred to as the "Minimal" Interface.)

'old' doc has Figure 5-4 (Free-running Timer); however, that's not included in the new one.

"Appendix A, Revision Information"

'new' doc specifically has a section for "Polaris Revisions" saying "As of Rev 8, none of the Polaris revisions specifically affected its Chroma Interface."

"Appendix B, Parameter Information"

There are some minor presentation differences. E.g., the 'old' doc may show the a value as "10" (binary) whereas the 'new' doc shows the same value as "2."

The tables showing the program 'layout' are entirely different, with the 'old' manual showing things quite pictorially - with the 'new' doc. showing it in a more tabular format (and providing details such as "range" and the value the parameter takes on when a "scratch" patch is created.

'new' doc has a complete extra section entitled "Polaris Parameters and Program Layout."

Appendix D

In the 'old' document this is a summary of the Chroma commands. In the 'new' document, this is a new 3 page section called "Polaris Objects and Streams."

newbie on the list

Jesper Ödemark [21010135]

New guy here, Swede with Chroma number 135 [model 2101] in the studio. It's in fact the very chroma that can be heard on the "Synthesizers von Gestern/Vintage Synthesizers" CDs. Yesterday I got even happier when I managed to find an original manual on Ebay UK.

Well, thought I should say a word or two to let you know I'm here...

electronically yours, jesper

Chris Ryan [21030691]

Welcome to the list, Jesper! Let us know if there's any help or information you need.

Olli [21010284]

welcome jesper!

Chroma with Memory Expander on eBay.de

Chris Ryan [21030691]

Jesper found that there's a Chroma for sale on eBay.de [item 3749564045].

It includes the EES MIDI kit and Chroma Cult memory expander. This may be the same instrument Sandro Traversi pointed out a year ago at the same site [see A mod Chroma on Ebay.de, September 2003].

Chris Ryan [21030691]

This auction includes a better picture of the right-side modification, which I've attached to this message. The Chroma Cult memory expander is described in Ken Ypparila's documentation as "two toggle switches that you mount on the right cheek block of the Chroma or on the back panel of the Expander." So I wonder what the extra controls might be: "Sound Bank" and "MIDI" knobs, and two extra toggle switches (labeled "MIDI Mode").

I've e-mailed Ken to clarify.

Chris Ryan [21030691]

Ken writes, "I'm not sure what that stuff is since the listing is in German. The memory expansion used two little toggles like the picture but this one has 2 sets so it might be something else."

I've submitted a question to the seller.

Jesper Ödemark [21010135]

So I wonder what the extra controls might be: "Sound Bank" and "MIDI" knobs, and two extra toggle switches (labeled "MIDI Mode").

As for what my german is worth I understand it has 200 memory positions and not just 50 after the mod. I guess the "sound bank" is a switch for memory position. In the text it is described as an EES-midi just like mine so the midi push button is probably the same as the sysex midi dump button on my unit.

Do compare with the pictures I sent you Chris, 4 switches, one button. Looks like mine... So it's just that 200 memory position mystery to solve.

BTW - I'm curious... how many more Chroma serial numbers with history will the new site be updated with? The guy selling three units among the ads hasn't had his three included for example...

Chris Ryan [21030691]

As for what my german is worth I understand it has 200 memory positions and not just 50 after the mod. I guess the "sound bank" is a switch for memory position. In the text it is described as an EES-midi just like mine so the midi push button is probably the same as the sysex midi dump button on my unit.

Do compare with the pictures I sent you Chris, 4 switches, one button. Looks like mine... So it's just that 200 memory position mystery to solve.

Yes, you're right. The seller writes, "The internal EES Interface (there is also an external one with the same features) features 4 switches for Midi Multimode on 4 channels, an additional knob for Midi Dump and a rotary knob for 4 sound banks increasing the number of sounds to 200. There is also a website about this Midi-Inteface from EES in Germany." I can't find this info at www.ees-musik.de.

The 200 patch expansion is the Chroma Cult memory expander.

(See my previous message with Ken Ypparila's comments.)

BTW - I'm curious... how many more Chroma serial numbers with history will the new site be updated with? The guy selling three units among the ads hasn't had his three included for example...

The current count at the new site--updated with this one we're discussing [21010260]--is 127. That's 33 of model 2101, a single 2102, 70 model 2103, 2 2104s, 4 unknown/incomplete/questionable serial numbers, and 17 Expanders [1631, 1633]. That's approximately 10 more than the current site. One duplicate has been eliminated.

There are still many people on the list whose Chromas are not in the registry ... :)

Jesper Ödemark [21010135]

Yes, you're right. The seller writes, "The internal EES Interface (there is also an external one with the same features) features 4 switches for Midi Multimode on 4 channels, an additional knob for Midi Dump and a rotary knob for 4 sound banks increasing the number of sounds to 200. There is also a website about this Midi-Inteface from EES in Germany." I can't find this info at www.ees-musik.de.

Depends on what he means. It's not on the EES site, but there is info on synrise.de and similar sites.

The 200 patch expansion is the Chroma Cult memory expander.

As I guessed - hey, I'm good at this, being a newbie and all! ;)

There are still many people on the list whose Chromas are not in the registry ... :)

Come on dudes - let's get the first complete listing. The Lords of the Mini site is trying the same and I have my version in the coming update of my EDP site.

David Clarke [21030085++]

I'll vote my $0.02 worth to ask that anyone that hasn't already listed their keyboard to please do so.

We don't need the keyboard's life story (if you'd prefer not to give it); rather, it would just be nice to know if S/N ABC is still in existence, etc.

Jerry Leonard [21030100++]

I'm guilty. I have three chromas and an expander. I'll get them registered this week.

one expensive chroma

Jesper Ödemark [21010135]

The one on german Ebay [see Chroma with Memory Expander on eBay.de above] went for 2460 euro!

And now when I'm here I can add I received my original manual that I won on EBay.uk the other day and at the same time came the original disc with the chroma-editor for Atari from Matthias Becker (former owner of my chroma). My chroma-editor has serial number 9 for those who cares... ;)