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ChromaTalk Archives: March 2012

Re: Question on the Poly Aftertouch / Pressure Sensor Kit Installation

Go to first message in thread, December 2011

Arun Majumdar [21030348] · Thu, 01 Mar 2012 03:11:28 -0500

On 12/30/11 1:39 AM, matrix wrote:

All done. The most challenging bit was definitely getting the vertical positioning just right. I ended up removing the green round felts underneath the keys and cleaned the keys while I was at it. I tested with and without the felts and couldn't quite tell the difference once I got things to my liking. I ended up leaving them off. Does anyone have an opinion on that?

I ended up putting some soft rubber washers under the keys to increase the "lever" action as I had to mount the bar a bit higher. I removed the felts but used some string that I wove through the posts to keep the washers and give a softer feel.

I have since setup my Kurzeil Midiboard to control the Chroma and that also works really great!

CC+ Strange Behavior

August B. Raring [21010148] · Sun, 4 Mar 2012 19:07:57 +0100

Hello,

a friend of mine burned an Eprom with the latest firmware and when I installed it on the CC+board and switched on the Chroma some LEDs started flashing, the data-readout showed some mystery signs and after some seconds the Chroma was dead!

So I reinstalled the older Eprom 2.14 again, powered up and the tuning-routine started as normal. But now the lower row of LEDs is flashing permanently and the No/Upper Link switches do not function, there is no sound and Set Split 37 shows no voice activity!

What could be wrong? Thank you for any help!

David Clarke [21030085++] · Sun, 04 Mar 2012 17:03:00 -0500

August - the most likely cause for the No/Upper Link settings and the lack of keyboard activity both relate to configuration settings for the CC+. It appears they may have been upset/changed during the efforts.

Specifically - the most likely parameter affected is the one to select whether the CC+ should run in the Chroma or the Expander. When the setting for the Expander is selected, the keys will be ignored (e.g., no Set Split key activity) - and the link buttons/LEDs have other assignments.

The first debug step would be to go into the configuration menu (Set Split-36) and then ensure all the settings are as you'd intend for the configuration: Configuration Interface & MIDI Support.

David Clarke [21030085++] · Sun, 04 Mar 2012 19:03:29 -0500

... the most likely parameter affected is the one to select whether the CC+ should run in the Chroma or the Expander...

Following up to my earlier note, while it would be recommended to validate that all the settings are as desired, the one specifically of interest is:

[Set Split][36] + P22

If you have a Chroma you'll want this set to 'Chro' instead of 'Pndr' (used of the Expander).

Another setting of specific interest:

[Set Split][36] + P17

Set to 'On' to ensure you have enabled local keyboard control.

When you have an opportunity, let us know how you make out.

August B. Raring [21010148] · Mon, 05 Mar 2012 10:54:18 +0100

Hello David,

that was it! My Chroma is working again! Thank you very, very much for your instant help!!!

(Another great help would be, if you would make the arpeggiator and lfo`s syncable to Midi-Clock, but I think this is a new thread ;-)

With best regards

August

Saving CC+ MIDI Edits?

Matrix [21030220] · Sun, 4 Mar 2012 11:02:36 -0800

I just noticed something odd with my Chroma. I can't save edits for a patch if the edits are made via MIDI. If I edit via the front panel changes are saved but via MIDI, nothing. The previous patch remains when I go back to it. Is this normal? Is anyone else seeing this?

August B. Raring [21010148] · Sun, 4 Mar 2012 21:17:37 +0100

Hello Matrix,

maybe Set Split 36 P6 : Parameter Changes disabled ?

David Clarke [21030085++] · Sun, 04 Mar 2012 16:59:13 -0500

I can't save edits for a patch if the edits are made via MIDI. If I edit via the front panel changes are saved but via MIDI, nothing. The previous patch remains when I go back to it. Is this normal? Is anyone else seeing this?

This can be normal behaviour, depending on how you have the CC+ parameters set up.

Specifically - the CC+ allows you to chose whether the MIDI CC messages should affect the 'instrument' (e.g., settings currently live in the voice cards) or whether it should affect the 'program.'

The former allows you to manipulate the sound of a patch without changing it - as you might want to do in a played-back sequence from a sequencer. The latter allows edits to the current patch.

Editing on the Chroma itself always affects the main program.

Check the setting of the "Select MIDI Continuous Controller Mode" from the CC+ configuration menu:

[Set Split][36] + P24

If "Inst" is selected, the Continuous Controller data will only affect the 'instrument', and not affect the program. (i.e., the changes are gone when the program is reselected, the Chroma is turned off, etc.) If "Prog" is selected, then any Continuous Controller data will change the values for Program 0 - and hence you'll be able to save it with the program (if you like).

(This selection was added as of firmware version 209)

Matrix [21030220] · Sun, 4 Mar 2012 16:57:33 -0800

That was it. Thanks guys!

New firmware update - help!

Heath Finnie [21030175] · Tue, 6 Mar 2012 21:10:31 -0500

Hi all,

Today I received my new [CPU Plus] firmware update. I carefully removed the old chip and placed the new one in. I turned it on and it wasn't right. Checked it again and one of the pins had bent which I stupidly didn't notice it at first. Then I went to put in the previous firmware (2.13) and it goes through the 16 steps of tuning, but then I have random lights blinking on the front. It responds to buttons, but no sound and the blinking buttons don't stop.

I then tried straightening the pin on the new firmware and reinstalled it but it just does a different kind of strange behavior. It doesn't even go through the tuning.

Any ideas?

Thanks!

August B. Raring [21010148] · Wed, 07 Mar 2012 10:19:36 +0100

Hi Heath,

I made a similar experience so look for the thread "CC+ Strange Behavior" and the answer by David Clarke that solved the problem!

Cheers,

August

David Clarke [21030085++] · Wed, 07 Mar 2012 20:00:59 -0500

Putting in a 'bad EPROM' (whether it is bad due to code, a failure, or a bent pin) will normally not physically damage anything. That said, when the computer attempts to run, it will be trying to execute garbage code. This could (and often will) cause parts of the memory on the card to have their contents overwritten.

What that means is that some/all of the stored programs might get wiped out or corrupted. It will also likely mean that the stored CC+ configuration parameters will get changed, which could make operation seem odd.

The corrupted stored programs can certainly prevent good sounds from being heard. As noted by August, the odd button behaviour could result from bad CC+ parameters too.

The good news is, all the CC+ parameters can be reset via the panel itself.

To debug, I'd recommend putting back in the 2.13 EPROM (since you knew that previously worked).

Once booted up, go into the CC+ Configuration Menu

[Set Split][36]

Now go through and set the parameters to some good defaults (or at least confirm the current settings are OK):

  • P1: Base Channel = 1
  • P4: Program Changes = Enabled
  • P5: Instruments Avail = all (7)
  • P6: Parameter Changes = Enabled
  • P11: Pedal 1 Select = Off
  • P12: Pedal 2 Select = Off
  • P13: Footswitch 2 select = Off
  • P14: Volume Select = Off
  • P17: Local Control = On
  • P18: MCM Mode = Cult
  • P22: Panel Config = Chroma

Go to P20, and move the data slider (to init the controller map)

Exit the config mode ([Set Split][36] again)

Create a scratch patch ([Set Split][39])

Store the scratch patch (say, to patch location P1).

See if you hear the scratch patch/the system works as expected.

If all seems well (aside from possibly having bad data in the other stored patch locations), you can either consider going to the new version of firmware (now that the pin isn't bent) or to reload patches into the 213 firmware.

Let us know how you make out.

P.S - as a general question to everyone on the list, I do have an "INIT" EPROM image which can be used to restore a board back to the 'factory' defaults (e.g., all 4 program banks reset, nominally configured CC+ parameters, etc.).

Is that something that people would use if it were placed on the 'firmware' page for the CC+, or would most people not need it/want it? (It's convenient if you're building a CC+ - but otherwise it might be just as easy to reprogram the CC+ settings through the front panel and reload the 4 banks manually, etc.)

64 Oscillators and 475 Knobs

Randel Osborne [21030467] · Thu, 8 Mar 2012 10:15:56 -0500

Greetings-

I took the following photos of my latest production run of Enablers. They include a few custom case shapes, as well as a bubinga Enabler to match Tom's Chroma and Expander casework.

enablers1

enablers2

enablersRandel

More fun than a wall of Marshall stacks!

For more info, please see: Chroma Enabler.

Rick Reed · Thu, 8 Mar 2012 10:19:42 -0500

I am seriously jealous. What part of the world are you in? Would love to request a visit!

Jesper Ödemark [21010135] · Thu, 08 Mar 2012 16:27:43 +0100

The left set with expander and enabler looks yummie and stylish indeed! :D

Dave Bradley [16330135] · Thu, 8 Mar 2012 09:37:34 -0600

Beautiful.

Peter Forrest [21010096] · Thu, 8 Mar 2012 15:47:06 -0000

Fantastic!

Antonio Tuzzi [Polaris 100036] · Thu, 8 Mar 2012 16:50:24 +0100

DROOOL!!!!

Tom Hughes [21030251+] · Thu, 08 Mar 2012 11:05:15 -0500

Thanks, that one's mine! The collective set (Bubinga Chroma, Expander, and Enabler) has been dubbed "Chromatropolis."

Werner Schöenenberger [21010114] · Thu, 8 Mar 2012 22:33:41 +0100

Definitely! Chapeaux

Peter Forrest [21010096] · Thu, 8 Mar 2012 22:09:50 -0000

But, thinking about it...... if there are 64 oscillators shouldn't there be an even number of knobs? OK I know this is not exactly important... :o)

Marais · Thu, 8 Mar 2012 17:25:29 -0500

So Randel, Shall we see the Enabler Sequencer next perhaps ? : )

Frank McGing [21010198] · Fri, 09 Mar 2012 04:36:08 +0000

Chromatropolis is a thing of beauty!

Magnificent work, Randel.

Polaris Membrane Panel Replacement

Chris Ryan [21030691] · Thu, 8 Mar 2012 22:54:37 -0800

New on the site this month: instructions for replacing the Polaris membrane panel, by Paul DeRocco [21030230]. The new panels Paul has produced solves a longstanding problem with the instrument. Those interested in the Polaris should check out the Polaris mailing list.

Dave Manley [21030547] · Fri, 09 Mar 2012 01:06:02 -0800

Fantastic job!

One tip - I've had to remove a number things held on by adhesive recently and have found that applying a relatively small amount of hot air makes the job very easy.

misc. pressure sensor

Chris Borman [21030194+] · Sat, 10 Mar 2012 16:12:28 -0500

A couple folks expressed interest in a video demonstrating what after touch pressure could modulate. Here is a YouTube video I just posted. In this case my Chroma has not made a peep in over a year so here is a monophonic version I installed in my ProOne. You just can't do this with only two hands. What a great way to start off a Saturday morning!

A few Chroma folk expressed interest in getting one of these for their ARP Oddyssey's and such. I'll give you guys the family price somewhere well under $200 when I figure that out. I'll also send you the optional controller board to expand the capability when I get that designed. This first version simply replaces the three mod wheel connections with two wires from the sensor array and a 22K jumper to GND.

Chris Borman [21030194+] · Sat, 10 Mar 2012 16:14:24 -0500

Of course this would help...

Luca Sasdelli [21010226] · Sat, 10 Mar 2012 22:38:15 +0100

My ARP Odyssey is of course impatient to see it... :) Anyway: do you need any mechanical investigation for that sensor?

Chris Borman [21030194+] · Sat, 10 Mar 2012 17:02:38 -0500

This application simply replaces the Mod wheel potentiometer with the monophonic keyboard pressure sensor. Assuming all Pratt-Read keyboards are the same, I should have the supporting key actuation structure figured out but later ARP design wise, I sold my AXXE awhile back so not too sure about the chicklet interface. Interesting though, they are used for Mod, Pitch and something else I can't remember, but they are in effect FSR sensors so you may have a simpler and more effective connection for that application. I suppose I could find the doc somewhere on my PC but may be better for you, who actually has such a device to take a look!

Chris Borman [21030194+] · Sun, 11 Mar 2012 11:40:32 -0400

OK I got pricing figured out, $140 + shipping ($18 US, $36 Intl) for any ChromaTalk member. Same terms as the ebay ad. This is for the 37 Key version. For 49 or 61, add $40 or $80 respectively. Just send me an email if interested.

Tom Hughes [21030251+] · Sun, 11 Mar 2012 15:54:13 -0400

Hi Chris,

When you say it replaces the mod wheel, does that mean the mod wheel then becomes non-functional, or do they then both perform the same function?

Chris Borman [21030194+] · Sun, 11 Mar 2012 16:39:34 -0400

I left out the MW wiring replacing it with the AT wiring in my Pro-One. There are a couple options. You could wire in a switch to select between Mod wheel or AT. Because the AT functions as a normally open switched rheostat, you could get away with wiring the MW and AT in parallel. Wired in series, The MW could be used to set the amount of AT. May also function that way in parallel with a little bit of resistor work. Or don't interrupt the MW circuit at all and wire the AT directly into the Ext. Filter Input. You could supply some variable MOD source even the MW output or a fixed voltage for input to the AT. If I were to put on in a 2600 keyboard, I'd likely just wire it to jacks making it completely flexible. A switch can also be configured to invert the operation of the AT. I'm looking into bi-polar operation where it could be used for pitch bend or a lever function. Without an IV convertor OP AMP circuit the AT has be be wired as a voltage divider so there is some loss of the range compared to a MW.

Luca Sasdelli [21010226] · Sun, 11 Mar 2012 22:55:53 +0100

Chris,

which output does it drive? Is the output a variable voltage or a variable resistance? In either case, which value range will it cover?

In the next few days I'll send you some keyboard closeups from my Ody.

Thanks

Chris Borman [21030194+] · Sun, 11 Mar 2012 18:30:33 -0400

It's not a true potentiometer like a MW. It only has two terminals; in and out, and functions as a switched variable Rheostat. Without a I-V converter circuit it needs to be setup in voltage divider configuration so there is some trade off between the low end, range and high end via a resistor to GND on the output. The FSR sensor is an NO switched 120K ohm variable rheostat. It does jump into it a bit upon actuation and maybe a cap could smooth out that transition. That and plug and play connectors for various ARP and OB synths, configuration switching, digital pot and a micro to track input V and dynamically reconfigure the V/network to simulate potentiometer function and range are all options that should end up on the eventual controller board. I was pretty excited Saturday morning how well just a simple 22K resistor to GND to complete the V/ circuit had worked. The modulation in the video can't be done without AT so this simple implementation ain't bad at all! And I am no keyboard player! Me just a drummer with a soldering iron goofing on a keyboard... Imagine the articulation a real keyboard musician could do with this!

Luca Sasdelli [21010226] · Mon, 12 Mar 2012 17:13:02 +0100

BTW: Chris, did you see this [EPiCK optical piano sensor bar]?

Chris Borman [21030194+] · Mon, 12 Mar 2012 17:03:37 -0400

That’s one hi-tech electronic optical sensor and a pile of micros and supporting code. Awhile back Brian mentioned to me he saw the new Rhodes Electric Piano with poly AT which includes optical sensors. The Clavichord playing the acoustic guitar sound had a lot of articulation. I like that. Sometimes so much so a few chords sounded out, but just like an acoustic instrument, you have to learn how to properly articulate it. I did not realize the Clavichord had a pressure sensitive keyboard. Thanks for that Luca!

John Leimseider [21030434++] · Mon, 12 Mar 2012 15:11:11 -0600

Has everyone tried the VAX77 from Infinite Response? It is a joy to play. We have one, along with a T8 and CS80 here at Cantos. I have a Chroma with the original pressure and a CS80 at home. I’m big on polypressure…

Chris Borman [21030194+] · Mon, 12 Mar 2012 18:21:43 -0400

So the Mellotron could also be the first multi-sampler?

Chris Borman [21030194+] · Mon, 12 Mar 2012 18:24:39 -0400

So you guys have the actual ARP2500 that Phil Dodds played [in Close Encounters of the Third Kind]?

Jesper Ödemark [21010135] · Mon, 12 Mar 2012 23:27:08 +0100

Good to know, when the little grey men arrive! :D

John Leimseider [21030434++] · Mon, 12 Mar 2012 16:15:54 -0600

Yes. It also has 2 wings that are not part of the original. The keyboard is also not original. The one in the movie had 2 stacked keyboards. I was told by Mary Lock, who was a tech at ARP at the time, that they threw away the white plastic shell when it was decided that it would never be used again… Damned shame… She worked at Chroma and Kurzweil after… We also have 2 of Keith Emerson’s keyboards, one of Patrick Moraz’, the Emu Audity, Patrick Gleeson’s EMU, etc. Check out the website… Lots of cool stuff.

Frank Hettlich [21030041+] · Mon, 12 Mar 2012 23:37:25 +0100

So you guys have the actual ARP2500 that Phil Dodds played?

They probably bought it from Bryan Carrigan, I guess. He offered it for sale a few years ago.

David Gowin [21030611] · Mon, 12 Mar 2012 15:44:35 -0700

Hmm, links don't seem to be working on Featured Instrument and Collection Checklist?

Chris Borman [21030194+] · Mon, 12 Mar 2012 18:50:39 -0400

Good to know, when the little grey men arrive! :D

Speaking of that, A friend of a friend way back when picked up the helm chair from the Starship Enterprise.

John Leimseider [21030434++] · Mon, 12 Mar 2012 16:38:35 -0600

They probably bought it from Bryan Carrigan, I guess. He offered it for sale a few years ago.

Yup...

John Leimseider [21030434++] · Mon, 12 Mar 2012 16:39:12 -0600

Hmm, links don't seem to be working on Featured Instrument and Collection Checklist?

It's working here...

John Leimseider [21030434++] · Mon, 12 Mar 2012 16:40:46 -0600

Also, our Chroma and expander are from Ralph Grierson, a brilliant musician who's played on more movies and TV shows than you can imagine!

Jesper Ödemark [21010135] · Mon, 12 Mar 2012 23:59:50 +0100

Speaking of that, A friend of a friend way back when picked up the helm chair from the Starship Enterprise.

Off-topic but cool! I still cannot grasp that they trashed everything from "2001". How I'd love to have HAL on my studio wall!!! :D

Re: I/O board problems

Go to first message in thread, December 2011

Paulo Semprini · Fri, 16 Mar 2012 12:44:29 -0700

OK, back at work on this -- I'm just about at the point of giving up, but I thought I'd try one more time.

Basically, I have a Chroma that is fully functional (keyboard, memory, MIDI, cassette interface, display, ADC, etc) except for the voice tuning.

Some details:

  • the power supply has been replaced with a Luca unit.
  • the channel mother board and voice cards were tested in another Chroma, and worked well & consistently.
  • managed to borrow the I/O board from a working Chroma and install it in this unit. Everything worked correctly & consistently.

From this, I conclude that the CPU board, power supply, mother board, voice cards, stack switch board are all good, and that the fault is confined to the I/O board.

What happens is that, on power up (or pressing the auto tune button, or pressing SS/50, or pressing the power supply reset button) a random number of voices will come up disabled. Repeated pressings will give me different combinations of disabled voices; basically what I have here is a very expensive random number generator. Sometimes I can get it down to two voices disabled; sometimes it's all of them.

What's been done to the I/O board so far: replaced one of the DACs that was faulty, replaced all the ICs (CMOS. TTL & opamp) associated with the DAC, replaced all ICs in the misc. I/O section & I/O strobe decoder section, replaced most ICs in the timer section.

The fact that the display & all other digital functions are working correctly leads me to conclude that the data lines are all good. All power rails are within spec and look clean on the scope.

The DAC output is trimmed to .0001V (using a calibrated digital meter). The 2 mhz timing signal (which comes from the CPU board, which is good) connects to two ICs (both replaced, along with the 50pf cap). This signal is not only used for tuning, but for the cassette interface, which works correctly.

Anybody have any ideas what I'm missing? (I know I'm missing something...) Could this be a bizarre matter of stray interference, or maybe faulty .1uf bypass caps?

Any suggestions beyond the usual suspects (which I believe have been covered) would be welcome.

Thanks.

Paulo Semprini · Sat, 24 Mar 2012 13:32:01 -0700

Decided to give up on this -- put it back together, and suddenly it's working. Don't know why, but at this point I'm not asking questions; just happy to get it off my workbench.

Thanks to Luca for his power supply, which is a fine alternative to the original boat-anchor that ARP designee, and for his continuing patience with stupid questions.

And thanks as always to Chris [21030691], for running the most useful synth site on the web.

A small CPS production run

Chris Borman [21030194+] · Wed, 21 Mar 2012 18:43:59 -0400

I've received a few inquires about CPS Kit availability over the last couple months. The last CPS build exhausted the PCB inventory. The high cost items that make a small production run prohibitive are the custom FSR and PCB set. I have FSRs available from my monophonic AT project so that leaves PCB fabrication. The board house I use has some minimum sq” of PCB order per run which I believe equates to 15 PCB sets (15 Mux, 30 Array). The idea here is to finance another round of CPS Kits with some PCB stock left over so when 6 months or so down the road the custom parts will be available to produce a CPS Kit for someone's Chroma.

One of the gentleman who inquired about CPS Kit availability has offered to front the cash to procure parts for another build with some excess PCB sets for future use, a gift to the Group. Why? Because he (nor I) want to see the CPS accessory fade out of existence and so he can have polyphonic After-Touch in his Chroma of course! I have one other guy committed to this purchase as well. I'd like to get 2 or 3 more committed to this build to soften the individual out of pocket expense and so I don't have to sit on someone else' cash for an extended period. Anybody?

$265 + Shipping: $15 US/$30 International. Ship time due to PCB manufacture lead time will be towards the end of April.

Please email me at [address removed]

CC+ alternate displays revisited

See earlier thread Alternate Displays to use with CC+ Alphanumeric Display Capability? - October through December 2011

Frank McGing [21010198] · Wed, 21 Mar 2012 23:21:53 +0000

I finally got around to installing CC+ firmware 2.16, the new UART and the Parallax LCD I had purchased some time ago. Unfortunately I followed the pinouts for J7 on the CC+ wiring diagram a little too literally, got the orientation of pins 1-6 on J7 the wrong way around and fried the Parallax module. Thankfully the Chroma survived the experience and is fully functional.

So, before I go ahead and get another Parallax module, has there been any further development regarding the alternative SparkFun controller (or equivalent)? Or is it planned at all at this stage? I seem to remember the discussion fading away some time ago.

Red text on black would be very nice for my second attempt at this!

Cheers
Frank

David Clarke [21030085++] · Thu, 22 Mar 2012 20:06:04 -0400

Unfortunately I followed the pinouts for J7 on the CC+ wiring diagram a little too literally, got the orientation of pins 1-6 on J7 the wrong way around ...

The AMP MTE connectors have a small arrow/notch on them to help identify pin #1. The red circle in the following picture highlights the pin 1 designation. A similar shape appears on the mating connector.

amp_mte

... has there been any further development regarding the alternative SparkFun controller (or equivalent)? Or is it planned at all at this stage? I seem to remember the discussion fading away some time ago...

The last discussion occurred on the mailing list in December (Alternate Displays to use with CC+ Alphanumeric Display Capability?)

No one had really made suggestions for other backpack/serial controllers, and no one had gotten in touch to express an interest in trying the version of firmware that supported the SparkFun controller.

I can still make that SparkFun-enabled firmware image available to people to wish to evaluate it - but I wouldn't want to make that an officially released CC+ firmware version unless users indicate that it would get used.

Luca Sasdelli [21010226] · Fri, 23 Mar 2012 03:22:11 +0100

Hi David,

I'm interested in trying the parallel way.

Cheers
Luca

Frank McGing [21010198] · Fri, 23 Mar 2012 13:24:50 +0000

Hi David

The AMP MTE connectors have a small arrow/notch on them to help identify pin #1. The red circle in the attached picture highlights the pin 1 designation. A similar shape appears on the mating connector.

Thanks! I won't make the same mistake again...

The last discussion occurred on the mailing list in December (Alternate Displays to use with CC+ Alphanumeric Display Capability?)

I re-read the discussion, and the only difficulty for me was in pre-configuring the SparkFun controller to work with the Chroma.

I can still make that SparkFun-enabled firmware image available to people to wish to evaluate it - but I wouldn't want to make that an officially released CC+ firmware version unless users indicate that it would get used.

I would be very interested, but I think I would need a step by step guide to configuring the controller. The soldering is no problem.

Cheers
Frank

New power supply and 47 IC later !!! back to life :)

Joël Cordier · Fri, 23 Mar 2012 22:18:22 +0100

I'm a tech and brought back to live a Chroma that was incredibly affected.

It all begun with a starving power supply that I replaced with a modern switching one. That day I discovered that the Chroma was in a deep Coma. A very long path that requested me to remove all the semiconductors from the IO board. By chance only 3 voice boards where defect (only 7 onboard). I counted 47 IC that where defect and replaced ! plus some capacitors and a diode. I suppose this is a record. Did the owned play a concert under a Tesla coil ? :) Now it work almost fine.

I still have some trouble with the keyboars. All contacts have been cleaned and don't seem to be the origin of the problem. I have some stacking notes. And also some random notes when the fridge turns off. The decoding circuit seems quite sensitive to surge pikes.

Does someone have a suggestion to get rid of this.

Thanks for your suggestions.

Joël

Luca Sasdelli [21010226] · Fri, 23 Mar 2012 22:49:33 +0100

Hi Joel,

I didn't count all replaced chips, but the last year I resurrected a Chroma with a myriad of replacement, main of them on Channel Motherboard and Voice Boards.

Your issue looks like a grounding problem: try to check if all board ground wires (green ones) are properly connected to metal frame in a single point, and from there to ground within AC inlet. One single ground wire per board. The switched mode power supply should be grounded both in AC in and DC out, because they're typically isolated.

Cheers
Luca

Joël Cordier · Sat, 24 Mar 2012 16:19:51 +0100

Dear Luca,

Thanks for this good info. It sound like it was that. On the back panel one screw fixing 5 ground wires wasn't fastened enough, it was actually too long. Very pleased by your kind help.

Enjoy your weekend.

Joël

CPU and SPSU

David Hobson [21030506] · Sat, 24 Mar 2012 21:49:56 -0500

Hello,

I am not new to the group but I am sort of new in asking questions. I want to purchase a new CPU and the switching power supply and I don't know how to go about it, sorry, I just don't know who to contact at what email and if I should pay first and what not. I would be grateful if somebody would set me straight.

As an aside I would just like to say that I am currently having my Chroma tuned at "Speakeasy vintage music" in Dover PA close to hanover where I live. I will the group know how the service pans out.

Thank you for your time.

David

P.S. my chroma is being calibrated so I forgot my serial#...sorry

Chris Ryan [21030691] · Sun, 25 Mar 2012 01:57:57 -0700

I replied to this in January: see How Can I Get a CC+? and How Can I Get an SPSU Kit?

I have you in the registry for Chroma 21030506; is that correct? Let us know how Speakeasy Vintage Music works out; perhaps I could include them in the Service Centres listing.

David Hobson [21030506] · Sun, 25 Mar 2012 11:15:07 -0500

Hello Chris,

I own two Chromas with the serials here below, thank you for the help...I am jazzed about getting these Chromas up to date as it were.

THanks again,

David Hobson

21030078 & 21030506

David Hobson [21030506] · Sun, 25 Mar 2012 13:29:54 -0500

Hello,

I currently own a midi interface, the black box with the ribbon cable that plugs into the scsi port(sorry, i can not remember the name).

I am wondering if the midi interface will still work with the CC+(I opted for just the CC+ without the midi hardware).

Thanks for your time,

David Hobson

Greg Montalbano, Analog Synthesizer Service · Sun, 25 Mar 2012 11:48:35 -0700

I had a Chroma in for service a few months ago that had the CC+ board -- plugged my Syntech (Chromacult/KMX) MIDI unit in, and it worked just fine.

David Clarke [21030085++] · Sun, 25 Mar 2012 14:46:28 -0400

... I currently own a midi interface, the black box with the ribbon cable that plugs into the scsi port(sorry, i can not remember the name). I am wondering if the midi interface will still work with the CC+(I opted for just the CC+ without the midi hardware).

David - the MIDI interface you describe is most likely the Syntech/Chroma Cult/KMX one.

This will work fine with the CC+, just as it would have with the original Chroma CPU board. The MIDI features that you'll have at your avail. when using that MIDI interface will be those that are supported by the KMX interface (versus the expanded functionality you might get with the native CC+ MIDI interface.)

For instance, the Syntech interface will allow some of the Chroma's parameters to be manipulated via MIDI continuous controllers. The native MIDI interface with the CC+ will allow all of the parameters to be controlled.

Some additional discussion on this is available here in the section that starts "...When compared to the Original CPU plus a Syntech MIDI interface, the CC+ has the following improvements: ..."

Best regards,

David Clarke

David Hobson [21030506] · Sun, 25 Mar 2012 14:22:45 -0500

Hello,

thank you for your replies..It was helpful.

Cannot wait for the CC+!!!

David

Screws

David Hobson [21030506] · Sun, 25 Mar 2012 14:28:16 -0500

Hello,

I have yet another question. What are the screws from the faceplate and back of the chroma (size, number, length)? I would appreciate any assistance in this matter.

Thank you,

David Hobson

David Clarke [21030085++] · Sun, 25 Mar 2012 15:37:36 -0400

Check out Screws, January 2009.

David Hobson [21030506] · Sun, 25 Mar 2012 15:10:08 -0500

Hello,

WOW!!! this has got to be the best synthesizer group going.

Thanks alot for the info,

David Hobson

Marais · Sun, 25 Mar 2012 16:39:20 -0400

Using black hardware looks really cool too and rings (?) for the under the control panel screws. Home Depot usually has it here in the states in their bulk bins.

Of course my voice boards are a little sensitive to movement (even after extensive cleaning) so I usually leave my top panel screws off so I can occasionally reseat the voice boards.

Luca Sasdelli [21010226] · Mon, 26 Mar 2012 10:11:25 +0200

Hi Marais,

try to redo all connector solderings on all DVBs: sometimes I find several of them with imperfections or breaks. Moreover, the "reseating" job could make them gradually worse.

A good shot could be to replace all DVB connectors, both on them and Channel Motherboard, with new ones.

August B. Raring [21010148] · Mon, 26 Mar 2012 20:46:33 +0200

Hi Luca,

do you know a distributor of the DVB connectors in Europe ?

Luca Sasdelli [21010226] · Mon, 26 Mar 2012 21:10:28 +0200

Hi August,

normally I buy my parts from DigiKey, where ship to Europe is free with > 100,00 US$ purchase, and you'll find lots of Molex connectors there.

In Europe you could search in RS-Components, Distrelec and/or in tme.eu.

Marais · Mon, 26 Mar 2012 20:04:23 -0400

DVB Connectors / Was Screws

Thank you Luca, this is like doing a break job with rotors on your own car, you put it off as long as you can : )

Is a big tough job to replace them and or touch up the solder with lots of disassembly ?

Do you have the Digitech or Mouser part # again ?

Thank you, M

Ps Seems like I am not the only one, so I feel a bit better. : )

Luca Sasdelli [21010226] · Tue, 27 Mar 2012 03:01:56 +0200

Re: DVB Connectors / Was Screws

Hi Marais,

this job is simply a matter of patience :) Just observe the usual static precautions and, because of the electro-mechanic nature of the matter, take care of solders quality. An unsoldering iron with vacuum pump is highly recommended.

the Molex codes should be:

  • DVB side: 38-00-1338 (mouser.com 538-38-00-1338, digikey.com WM2817-ND)
  • CMB side: 22-03-2082 (mouser.com 538-22-03-2082, digikey.com 22-03-2082-ND)

The Molex KK series is wide, so you can choose among various models around. Just in case, I kindly ask other list people with similar codes for compatibility.

eproms

David Hobson [21030506] · Wed, 28 Mar 2012 13:53:17 -0500

Hello, the is and eprom next to the cpu on its own board...does anybody know where I could get one?

I have my second chroma opened and I find that this eprom is gone..I am at a point where I could fix my cc+ and spsu and making this synth work as well as my original does.

If I could find an eprom(u2,i think) I could fix this my second Chroam.

Any help would be appreciated.

Thanks for your time , David

Luca Sasdelli [21010226] · Wed, 28 Mar 2012 21:31:45 +0200

Hi David, if you mean the I/O board, left to the CPU board, it's the keyboard scanner firmware (see EPROM Code).

David Hobson [21030506] · Thu, 29 Mar 2012 00:50:20 -0500

Thank you,

I cannot yet identify the eprom my repair guy told me about...but I sure do hope someone would like to make some money by providing one...(once I figure which one he is talking about.)

Thanks alot again,

David Hobson

David Hobson [21030506] · Thu, 29 Mar 2012 15:28:14 -0500

New Eprom

Hello, I need a eprom, Help!!!

I did not know which burnt eeprom to get but now my repair man says it is on the "keyboard encoder. What I would need is the new program for the eprom in a zip file with the newer program so the he can burn the new eprom. So maybe somebody has one of these chips help?

Thanks , David

P.S., I have paypal

Leonardo Ascarrunz [no serial number] · Thu, 29 Mar 2012 14:32:26 -0600

Re: New Eprom

The keyboard scan code is available on the website [see EPROM Code].

David Hobson [21030506] · Thu, 29 Mar 2012 16:25:22 -0500

Re: New Eprom

Hello Leonardo,

Thanks for finding that for me...one of these days I am going to read the whole site...LOL

David Hobson [21030506] · Thu, 29 Mar 2012 16:35:06 -0500

Re: New Eprom

Hello yet again,

I managed to get my hands on an eprom...Thanks anyway

question about midi and cc+

David Hobson [21030506] · Fri, 30 Mar 2012 13:17:36 -0500

Hello,

I just purchased the cc+ and installed it. It works great! But I have one problem...my syntech midi interface may be having problems sending sysex to my computer. I saw in the online documentation that you need(?) to rezuest a 50 patch bank to transmit and that you need to call up p23 to do this...What is "p" and how should i go about this?

David Hobson [21030506] · Sat, 31 Mar 2012 17:25:46 -0500

No sysex dump

Hello,

Let me explain my problem...I have a syntech midi box and i just installed the cc+, i can see my Emagic midi box showing activity when i play the chroma, but i do not know how to perform a sysex dump from the chroma to the computer. Maybe someone can walk me through this.

See Midi problem solved, April 2012

Tapper Assembly on eBay

Chris Ryan [21030691] · Fri, 30 Mar 2012 12:43:34 -0700

Item #300688342078, starting bid USD$19.99, no bids yet, ends April 2.

This seems to be another part from Chroma 0008. See Nobuya's post serial # 0008 Chroma, July 2011.

Picture from the auction:

eBay300688342078

Doug Wellington [21030300] · Fri, 30 Mar 2012 13:15:24 -0700

I'm putting together my own expander from scratch, and I was thinking about bidding on that, but now I'm not so sure. Seems like bad karma...

Anybody know where I can get a tapper?

Nobuya Tanaka [21030272] · Sat, 31 Mar 2012 05:52:09 +0900

Doug,

You don’t need to worry about bidding it. It’s hard to prove that the tapper was removed from my Arp Chroma.

Doug Wellington [21030300] · Fri, 30 Mar 2012 14:52:01 -0700

Thanks, I may go ahead with a bid, but I've been thinking about using E-Switch 5500 switches for my front panel instead of trying to make a membrane panel...

Go to next message in thread, April 2012