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ChromaTalk Archives: June 2006

Chroma CPU Replacements (CC+) Are Ready For Order

Chris Ryan [21030691] · Thu, 1 Jun 2006 07:52:10 -0700

Great news from Dave and Sandro:

After taking the time to adjust the interface to better fit in the Expander, and to perform additional testing on a new circuit board, we're now ready to start taking orders for the the Chroma CPU Plus (CC+).

The Chroma CPU Plus (CC+) board is intended to provide a replacement for Rhodes Chroma and Rhodes Chroma Expander CPU boards. In addition to replacing failed/damaged boards, this board also includes the following additional features:

  • Built-in support for 4 banks of 50 patches;
  • Native on-board MIDI support (including the ability to have all Chroma controllers sent/received via MIDI CC);
  • MIDI SyxEx implementation which directly allows the load/dump of patches in Syntech format;
  • Support for custom MIDI controller maps;
  • Built in hardware interface to support a future alphanumeric display;
  • Local Control Mode;
  • 'One touch' scratch patch creation;
  • Voice Watch Mode;
  • Battery-less operation;
  • One CPU/program load for both the Chroma and Expander (i.e., boards directly interchangeable between the two, without the need to install different PROMs);
  • Lower Power/Lower temperature operation; and
  • MIDI Activity Indicator.

Installation can be done without needing electrical experience - no soldering or wiring is required. Simply unscrew the old CPU board, screw in the new one and attach the provided (optional) cables. That's it.

Details are available on the updated Chroma CPU Plus page.

Jesper Ödemark [21010135] · Fri, 9 Jun 2006 09:35:15 +0200

Am I blind or is there no price mentioned? I'm capable with a soldering iron and is not afraid to open and fool around most of the time, but I'd like to hear a price mentioned and is still not fully informed about how to hook up to get a knobby-Chroma. ;)

Enrico Dibennardo [21030494] · Fri, 9 Jun 2006 11:09:59 +0200

All kind of information is present (Imo) on this page that's surely the same page you saw already.

Here's price infos anyway: $319 USD/€265 CC+ CPU Board (with interconnection kit): $369 USD/€308

They seem to be available both from Canada or from Italy.

Jesper Ödemark [21010135] · Fri, 9 Jun 2006 11:22:40 +0200

Hi List!

Anyone (excl David & Sandro) who has installed it yet and has feedback to give regarding fuctionality etc?

Jesper Ödemark [21010135] · Fri, 9 Jun 2006 12:06:21 +0200

original midi CC vs. the new CC+

Hi list!

Now I really read everything available on the CC+ on the site and checked pricing etc. My main interest is to add a knob box to the Chroma. I don't have a problem with small patch storage space nor a malfunctioning CPU since mine was replaced in modern days (circa five years ago). Today I run the EES chroma interface to get midi access in and out and it works like a charm. I load and dump patch data from the Atari through the Kirschning Chroma-Editor.

I doesn't own any knob box and have very limited knowledge about the tech side of midi so that's why I'm turning to you.

Is there a point in borrowing a midi knob box to check if I can use it as of today, hooked up on the line between chroma and atari? Or is the old Chroma interface blocking out the ability to control parameters (live) from a knob box?

I really admire David's and Sandro's work and I can really see the benefits, but I don't want to get a CC+ unless it (A) does what I want, ie works good with an external knob box and (B) doesn't "add" features I already have in my chroma.

Did you guys follow? All help appreciated!

David Clarke [21030085++] · Sat, 10 Jun 2006 15:37:51 -0400

Anyone (excl David & Sandro) who has installed it yet and has feedback to give regarding fuctionality etc?...

Jesper - the offering to the group was made at the beginning of June.

It is too soon for the parts to have come in, boards to have been assembled, tested and already shipped.

The CC+ units are not 'off-the-shelf'; rather, they're being created as ordered. What this means is, no one will have one of these received and installed yet.

[As was noted in the "How Can I Get a CC+?" section of the CC+ article we have estimated available of those initial orders to be 1 month.]

By way of a mini CC+ update, I can report that there has been a strong amount of interest from the members of the group. So much so that the we already have confirmed orders for all of the CC+ circuit boards which had been created for the first production run.

This statement shouldn't dissuade others from getting in touch though as we're keeping track of the additional order requests and once we reach a minimum quantity (as noted in the "How Can I Get a CC+?" section of the CC+ article), we will be able to confirm more orders.

Thanks to all who have gotten so far.

David Clarke [21030085++] · Sat, 10 Jun 2006 15:38:54 -0400

Re: original midi CC vs. the new CC+

My main interest is to add a knob box to the Chroma.... Today I run the EES chroma interface ... Is there a point in borrowing a midi knob box to check if I can use it as of today, ... I really admire David's and Sandro's work and I can really see the benefits, but I don't want to get a CC+ unless it (A) does what I want, ie works good with an external knob box and (B) doesn't "add" features I already have in my chroma.

Jesper - with regard to a MIDI knob box, the real question will be 'what features does the MIDI interface have that would allow me to control the Chroma's parameters.'

In order for an external MIDI knob box to talk to the Chroma, you need to send the knob data to the Chroma, and you have to have the Chroma understand/interpret/act upon that knob data.

There is no unit of data in the MIDI specification specifically called "knob data", and so the knob information needs to be transported over one of the standard MIDI mechanisms. In most common usage, this will be done by one of two means - either by MIDI Continuous Controllers (CCs) or perhaps by MIDI System Exclusive messages (Sysex).

A stock Chroma does not understand MIDI, and so over and above the requirement to have a knob box send the data, there's an additional requirement for the Chroma's MIDI adapter be able to translate the sent data into something that the Chroma will understand.

Not all Chroma MIDI interfaces are created equal, and not all are guaranteed to be able to support the manipulation of parameter data on the Chroma. For instance, I'm not aware that the JL Cooper ChromaFace can do this - that interface may be limited to only handling MIDI Note On/Note Off information.

So - the first questions you have to ask are:

  1. What sort of data can my MIDI knob box send (e.g., Sysex or Continuous Controller data) and
  2. What sort of data can my Chroma MIDI interface convert into Chroma parameter commands.

The answer to #2 is the most important one to start with. If the answer to #2 is "none, my Chroma MIDI interface does not allow the control of Chroma parameters", then there is no way you're going to be able get any MIDI knob box to control the Chroma parameters.

If the Chroma MIDI interface can control parameters on the Chroma, then you'll need to know how it does this. (i.e., sysex or Continuous Controllers).

You'll then have to match what the Chroma MIDI interface supports with the answer to #1. For instance, if your knob box can only support sending parameters via MIDI Sysex, and your Chroma MIDI interface can only change Chroma Parameters via MIDI CC's - then you're stuck, and will not be able to easily achieve what you'd like.

If your Chroma MIDI interface supports the changing of Chroma parameters, and if the MIDI knob interface can send those sort of commands - then you should be able to control the Chroma from the MIDI knob box.

I do not know what sort of capabilities the EES interface has in this regard.

I do know that the Syntech MIDI interface will allow control over some of the Chroma's parameters via MIDI Continuous Controllers. The mapping between CCs and Chroma Parameters is summarized in the Syntech Manual. If you had a MIDI knob box that sent the continuous controllers noted in that interface, then they could be used to control the noted parameters.

In terms of the new Chroma CPU Plus (CC+), it is important to note what it is intended to do (and what its not). Simply adding a CC+ will not give you any special 'knob-specific' features. In the default 'Cult' emulation mode, the CC+ will offer the same Continuous Controller mapping offered by the Syntech interface. In the 'custom' mode (selectable from the interface), the CC+ will provide continuous controller mapping for all parameters on the Chroma (as noted in the material in Chroma Expansion Board; MIDI).

While we're on this general topic - I would like to take this opportunity to thank Ken Ypparila [21030229] for continuing to provide the Chroma Cult/KMX/Syntech MIDI interface. It is a great product at a good price - I have only good things to say about it.

If someone were only looking to add MIDI to a Chroma, and didn't want any of the other features offered by the CC+, the $200 Syntech interface would still be my best recommendation to do so.

Jesper Ödemark [21010135] · Tue, 13 Jun 2006 15:40:00 +0200

Doepfer Pocket Dial and Chroma CC+?

Hi List!

I'm at work and will answer David's kind responses to my CC+ Q's later, but just a Q to sort out in the meantime. Will the Doepfer Pocket Dial work with the CC+ you think? And do I interpret the CC+ and the Pocket Dial that I can program it to control Chroma settings 1-16 on bank 1, 17-32 on bank 2, 33-48 on bank 3 and 49-50 on bank 4 (for example).

As mentioned numerous times before I'm no midi guru and think that analogue stuff should stay analogue ;) but since these are rotary encoders I guess they work better with the Chroma than sliders. True or false?

For sale: Chroma Cult/KMX MIDI interface

Greg Montalbano, Analog Synthesizer Service · Sat, 03 Jun 2006 10:29:36 -0700

Hola -

I've come across a spare MIDI interface for the Chroma -- tested it out, & all functions are good. As you all probably know already, user manual & full details can be found at the site.

Asking $130, US shipping included; will ship worldwide for whatever the extra postage turns out to be.

Voice Card on eBay

Chris Ryan [21030691] · Thu, 8 Jun 2006 08:04:47 -0700

Item #7421333229. Current bid US$0.50. Ships worldwide. Ends June 12. Similar to other recent voice card auctions.

Volume and effects pedals and footswitches

Paul Hackett-Evans [21010094] · Sat, 17 Jun 2006 00:16:32 +0100

Hi everyone,

Please can someone advise me on readily available possible alternatives for use as volume and effects pedals for my Chroma? Also footswitches to use for the Chromas sequence footswitch jack?

I'm still looking out for original Chroma ones but modern alternatives like Roland, Yamaha etc will do if there are any suitable ones you know of. Anything I might be able to buy readily in UK music shops or online would be great.

I have a Chroma dual footswitch for sustain etc, I only need help to choose suitable pedals for the above.

The Chroma as a MIDI master keyboard

Paul Hackett-Evans [21010094] · Sun, 18 Jun 2006 01:40:58 +0100

Here's another question for anyone who may know:

The Chroma is sixteen-note polyphonic at a maximum, normally used as an 8-voice poly synth. Does that have any bearing on the maximum number of notes that its keyboard can transmit over MIDI at one time? If I play more than sixteen notes at once (I have 33 fingers and come from the planet Zog), will the Chroma transmit all of those note on/off commands over MIDI, or is it limited to sending a maximum number of notes?

I've tried this to see if I can get to the bottom of what's going on: select a string sound on my Sampletank demo, hold the sustain pedal down, and play a loud bass note so the drone is clearly heard. Then play the highest notes as a descending glissando. I have to play the 33rd note (using all my fingers!) before the drone voice is robbed to provide the next high note. Sampletank is supposed to be 64 voice polyphonic. Is the Chroma reallocating the note, or is Sampletank running out of resources? How does the Chroma behave as a master keyboard in terms of polyphony?

I haven't had a problem with it as a master keyboard. Far from it, the Chroma is a joy to play as a synth or as a master keyboard. It's the only one I like playing, the feel is so unique. I've never heard less notes than I've played at once through anything connected to my Chroma through MIDI, but then I'm complete rubbish as a player and I doubt I'd really hear it if there was a note reduction in transmission.

Anyone know more about the Chromas behaviour as a master keyboard?

Thanks
Paul

Ps if anyone has a spare black Chroma key, please let me know, Roy needs one for a Chroma hes restoring. Thanks

Greg Montalbano, Analog Synthesizer Service · Sun, 18 Jun 2006 21:08:43 -0700

Easiest way to find out is using Midi-Ox (a free download, which is one of the most useful MIDI tools I've found). In its main screen, it will show you the note on & off info for what you're playing -- push down 33 notes at once & watch the results.

Corley Brigman [21030386] · Mon, 19 Jun 2006 05:37:59 -0700

If I play more than sixteen notes at once (I have 33 fingers and come from the planet Zog), will the Chroma transmit all of those note on/off commands over MIDI, or is it limited to sending a maximum number of notes?

Most controllers send a note-on when the note is pressed, and then forget about it as far as externally goes (and then send a note-off when released). I've never seen a controller that couldn't have all 61, 88, etc. keys triggered at once, but one may exist.

I have to play the 33rd note (using all my fingers!) before the drone voice is robbed to provide the next high note. Sampletank is supposed to be 64 voice polyphonic.

I will bet this is a stereo/mono thing. I've seen a lot of times where something is X voice polyphony, but each stereo sample uses 2 voices. So if your samples are stereo, you might only get 32 before you run out of voices. Check, and try something mono to be sure if necessary.

Waiting on my CC+ board to find out how good a controller the Chroma is. It feels a little weird compared to other keyboards I've used, but it's way better than the Polaris....

Jesper Ödemark [21010135] · Mon, 19 Jun 2006 15:32:29 +0200

I remember when I still had my PS-3200. Full 48 note polyphony... not very useful though! ;)

Chroma for sale on Ebay (USA)

Paul Hackett-Evans [21010094] · Wed, 21 Jun 2006 11:08:31 +0100

Not mine!

Look at item number 150000347251.

Chroma serial no 21030046 [sic — see below].

The seller says: "This is an incredible analog / digital hybrid synth. It has 64 keys ( E to G). There is a lot of info on the web, including a dedicated site. I would prefer to have the unit picked up in Oceanside, CA, but would consider shipping. The unit weighs about 75 lbs so shipping and insurance won't be inexpensive. This one has a low serial number, see the pic.

This is a rare synth in very good shape. The membrane buttons are all in excellent condition. The wood could use some refinishing, but it too is in good shape. The top has a couple of scratches on it. I haven't used this in about nine years, but it worked fine when it was packed away in a protected box.

I also have the original dual pedal that is in good shape. Also, the volume knod (sic) is broken, but the pot still works."

Bidding starts at $50. Sometimes I wish I lived in America...

Chris Ryan [21030691] · Wed, 21 Jun 2006 12:43:09 -0400

This is actually #0016, one of the first fifty and no model number [I was wrong--see next message]. The seller, Lloyd Trammell, has been in touch with me. I was going to forward his info to the list but am a few days behind on e-mail. He writes, "The serial number is 0016. I am attaching three pix [I will add these to the registry asap]. On the exterior, everything is in very good shape, no holes in the membrane. The volume fader has the top part of the shaft broken, but still can be adjusted. The top has a few scratches and the wood looks good, would probably do well with a new coat of poly or some kind of sealer. The top key is a lighter color than the others. I would accept offers from the group instead of parting it out or selling it as a whole on EBay. I live in Oceanside, CA (southern CA) and would prefer someone picks it up instead of shipping. I think it is worth at least $600, probably more don't know for sure. I also have the original two lever pedal somewhere."

Chris Ryan [21030691] · Thu, 22 Jun 2006 21:04:37 -0700

This is actually #0016, one of the first fifty and no model number.

I spoke too soon: it is #21030016, now added to the registry.

Molex Connectors from Chroma

Krisnallah Sumy [21010282+] · Wed, 21 Jun 2006 15:38:06 +0200

I am working on the aux board as I wanna swap my powersupply with a meanwell t60B

Can anyone here in space tel me the type number of the MOLEX connectors used in Chroma's powersupply Can't find the wicked Molex connectors in the netherlands I tried everywhere

Christian Kleine [21030210] · Thu, 22 Jun 2006 17:24:50 +0200

Hi Sumy,

I believe i have some spare Molex connectors from my last power supply swap. I'll search for them and let you know.

Aftertouch

Uro [21030401] · Thu, 22 Jun 2006 09:05:43 -0700

For Aftertouch, is there any sequence of serial numbers that can be identified, or are they just random?

Jesper Ödemark [21010135] · Thu, 22 Jun 2006 18:46:16 +0200

My guess is random 'cause I always thought the aftertouch board was optional and as such very expensive...

electronically yours, jesper & 21010135 - without aftertouch :(

Connection at J27

Brian Robison [21030175] · Fri, 23 Jun 2006 14:45:59 -0400

Hi, all--

I recently acquired instrument #21030175. It seemed to be in working order (save for five dead keys), but it was caked with foam rot.

I cleaned away 99.5% of the crud, but then the instrument didn't operate when powered up. (A few LEDs in the bottom row lit up, but nothing showed in the program number or data readout displays, and it didn't respond to any buttons, including no "tapper" response.)

It turns out that when I opened the chassis to remove foam crud from the interior, I inadvertently disconnected the 3-pin connector at J27 (connecting the EQ board to the balanced-output transformers to the left of the keybed, just behind the mod levers).

Now comes the embarrassing part: I restored this connection in a way that seemed obvious at the time, but which was almost certainly backward, because when I powered up the instrument, nothing whatsoever lit up... and when I checked inside, the fuse was blown.

I'm currently mired in the process of trying to replace the fuse (another question in another message, coming soon). Just to check, though I tried patching in a fresh fuse (using test leads to bypass the old one) with J27 properly (?) connected. The transformer hums, but again, despite a few LEDs lighting up, there's no activity in the program number or data readout displays, and no response to buttons.

So, I would be grateful for, first, confirmation of the correct connection at J27 (what's the left-to-right sequence of the wires?), and second, any hints on what else may be involved, other than the fuse. (I don't see any other points disconnected during crud removal.)

David Clarke [21030085++] · Fri, 23 Jun 2006 17:38:20 -0400

...It turns out that when I opened the chassis to remove foam crud from the interior, I inadvertently disconnected the 3-pin connector at J27 (connecting the EQ board to the balanced-output transformers to the left of the keybed, just behind the mod levers).

Brian - the good news is that a site-search from the main Chroma page for 'J27' will turn up a diagram showing the connector orientation for the transformer.

The perhaps-no-so-good news is that I wouldn't expect a bad transformer connection to be enough to make the Chroma unwell.

... I tried patching in a fresh fuse (using test leads to bypass the old one) with J27 properly (?) connected. The transformer hums, but again, despite a few LEDs lighting up, there's no activity in the program number or data readout displays, and no response to buttons.

If you have an oscilloscope, and are electrically inclined, the first, best thing to look at will be the nature of the 5V signal coming from the power supply - as well as the characteristics of the voltage present on the top of that large capacitor in the power supply. These are the two most common areas that you'll see a Chromas health in. (If that large capacitor has never been replaced in the history of that Chroma, it is likely going to be due for replacement - and a look at the voltage levels on the top of it will let you know one way or another).

Searching through some of the old archives will also have some other general good trouble-shooting ideas.

Good luck in your efforts,

David

Brian Robison [21030175] · Thu, 29 Jun 2006 13:44:36 -0400

Reviving #21030175

Hi, all--

It turns out that I did correctly re-connect the (accidentally unseated) J27, so the synth's problems must stem from something else.

My current best guess is that some other connection unseated while I was cleaning foam crud off the exterior... in particular, to get at the crud on the bottom surface, I turned the instrument up to rest on its back panel. If anyone can suggest likely culprits for a loose connection that would result from doing so, I would be most grateful.

Go to next message in thread, July 2006

Fuse specification?

Brian Robison [21030175] · Fri, 23 Jun 2006 14:56:22 -0400

Hi, all--

In the process of reviving instrument #21030175, I need to replace the fuse. It doesn't look like any fuse I've seen before--or, more to the point, any fuse stocked by my local Radio Shack.

The internal sticker specifies a 1A 250V fuse, but no other characteristics. I would be grateful to hear from anyone who has replaced the original fuse, as to just what you used as a replacement.

Also, after discovering to my horror that the dead fuse is soldered to the power supply board, I noticed in the service manual a "fuse clip" included in the parts list (ha!). I plan to install a fuse clip on the board so that I never again have to go through my current epic struggle to remove the @#$%%&^*#^&%$ dead fuse... so, I'd be grateful to hear from anyone who has done the same (was the procedure as simple as it appears it ought to be?).

David Clarke [21030085++] · Fri, 23 Jun 2006 17:56:58 -0400

The internal sticker specifies a 1A 250V fuse, but no other characteristics. I would be grateful to hear from anyone who has replaced the original fuse, as to just what you used as a replacement.

Technical Service Bulletin SN3-008: Chroma Primary Fuse is a good one to look at.

Based on that you're looking for a 1.0 -> 1.2 Amp Slo-Blo type fuse (should probably be rated for 250V).

Size-wise, a 'standard' fuse used with fuse clips (and as found in those Chromas which have clips already installed), is a 1 1/4" x 1/4" glass fuse.

WRT Radio Shack, you'd be looking for something like 1.0-Amp 250V 1¼x¼" Slow Blow Fuse (4-Pack) (Model: 270-1021, Catalog #: 270-1021).

...Also, after discovering to my horror that the dead fuse is soldered to the power supply board, I noticed in the service manual a "fuse clip" included in the parts list (ha!). ...

I'm not sure the conditions under which the different fuse setup was used - but I'm aware of Chroma power supplies that have the more standard 'fuse clips' (which accept a standard glass fuse), as well as other boards which don't have clips (instead having fuses with the leads preattached, for direct soldering).

If you did find it difficult to attach fuse clips to the exist power supply - the leaded fuses are still available to be gotten (and probably could be ordered on-line through companies like Digikey).

Voice Card on eBay

Chris Ryan [21030691] · Sat, 24 Jun 2006 15:25:04 -0700

Item #300000817698. No reserve, current bid US$26, ends June 27. "This Rhodes Chroma Voice Board has no pulled chips. That means there are 2 CEM chips and 4 Tempco resistors on this board."