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ChromaTalk Archives: October 2009

Re: Introduction and pressure sensor

Go to first message in thread, September 2009

Tim Siefkes [21030850] · Thu, 01 Oct 2009 04:09:50 -0500

I watched the demo video with Jordan Rudess playing an extended Continuum solo and was fairly knocked out by it. I was eager to try one too, until I saw the price tag. Well worth it, just beyond my reach at the moment. Congratulations, and I'd love to hear some of your music created with it, once you get it up and running. That would be a fine addition to anyone's arsenal! Please keep us posted!

Andrew Dalebrook [21010180] · Fri, 2 Oct 2009 09:14:10 +1300

Hi Chris (Borman)

This is good news about the pressure sensor, and I'm interested, but would there be any possibility of seeing the thing in action? Apologies for any mistrust implied, but I think you have to be a little watchful these days.

Chris Borman [21030194+] · Thu, 1 Oct 2009 16:45:00 -0400

Andy,

I haven't put a lot of thought into a marketing plan but that's a great idea! Maybe a couple wav files and youtube video? May even get a technical page put up on the website - Wouldn't that be cool!

I'm about three weeks from a production unit and will have something to e-demo by then. btw - are you interested in the economy model or the full 64 key model?

Daniel Rickenbach [21010172] · Fri, 2 Oct 2009 00:32:18 +0200

Hi Chris (Borman)

I'm interested also in the 64-key model, but first I have to calculate, if it's in my budget. Can you say, how much it would cost, 64-key version + shipping to switzerland?

Chris Borman [21030194+] · Fri, 2 Oct 2009 09:57:25 -0400

I have another International shipment to figure out. USPS International was suggested so I'll try them unless you have some other preference. I'll get on their website when I get home later today and get you the shipping cost.

Thanks for the interest!

Andrew Dalebrook [21010180] · Sat, 3 Oct 2009 06:52:50 +1200

Sorry to the list for the "bird's nesting" ;)

Chris, I'd probably say the cheaper one too, but I'd really like to see what it could do first. Of course, I'm international as well, so the shipping could be expensive.

The next question is: can the CC+ send out poly aftertouch? I seem to remember the Syntec interface could if you were one of the "lucky few" who had the pressure interface installed.

Chris Borman [21030194+] · Fri, 2 Oct 2009 17:19:07 -0400

Well, Chris R offered a Technical page on the website but that will take some time to put together and publish. If you don't know what polyphonic pressure offers, certainly some audio wav file demos or videos will fill you in and is a great idea to put on the website. Thanks for that suggestion. So far most folks want the full 64 key version. I have the 62 key size substrate and just need to order the larger size. Not a big difference in terms of time to get the remaining parts. 3 weeks should be sufficient time to get all parts in and assemble the kits ready to ship. I am hoping to do production runs of 10 so make sure you ask all your friends or order! Eventually I will (have to) figure out how to invoice though paypal. That willl happen tonight or early tomorrow AM...

Anyway, the Chroma will send poly pressure through the Syntech (which is what I have) and the CC+. My setup is the Chroma, Oberheim Xpander and Kurzweil Digital K2000rs, all of which recieve poly pressure.

Jesper Ödemark [21010135] · Sat, 03 Oct 2009 15:44:35 +0200

Chris Borman skrev:

I haven't put a lot of thought into a marketing plan but that's a great idea! Maybe a couple wav files and youtube video? May even get a technical page put up on the website - Wouldn't that be cool! I'm about three weeks from a production unit and will have something to e-demo by then. btw - are you interested in the economy model or the full 64 key model?

Hi Chris,

I'm still considering the offer and thinks a site with clips sounds great. How much would shipping to the old world be? And, I think I speak for most europeans living in countries with a high VAT percentage on imports; Are you OK with lying through your teeth on the value declaration? (Swedish VAT is 25% on the total amount including shipping)

Frank McGing [21010198] · Sat, 03 Oct 2009 15:46:34 +0100

As a European living in Ireland, and paying 21% VAT on the total amount, also including shipping, I concur!

Chris Borman [21030194+] · Fri, 9 Oct 2009 10:41:23 -0400

Sure, we can declare an appropriate value on the shipping documentation. You have to let me know what you would like declared.

Progress update on the Chroma Pressure Sensor (CPS) Kit - I'm having registration issues with the FPC sensor length so I have to open up my space & trace resolution and reduce the total sensor length down to 16 keys. The outcome will result in only a single 64 key (full keyboard) CPS Kit being offered with 4 individual sensors. This alternate configuration requires the addition of two FPC-to-Ribbon cable jumper PCB's to interface the two outer sensors to the main mux board. Cost is a wash for the sensors due to the short length, but the additional hardware adds $20 for two mini PCB's, connectors and cables so the one and only full 64 Key CPS Kit price will be $365. Should take a week or so to mod the schematic and layout, so the first production kits will be ready the second week of November. I still have not invoiced those of you who were ready to buy or figured out international shipping so give me a bit more time on that - obviously not my favorite task. Maybe someday I will have export and accounts payable departments to handle that!

CPS documentation will be ready for Chris' November website update.

Arun Majumdar [21030348+] · Fri, 9 Oct 2009 10:53:56 -0400

Hi Chris,

Thank you for the progress report. No problem for the fluctuations in cost with me whatsoever - I think it is well worth it.

I look forward to hearing progress and am ready to pay whenever this is completed.

David Clarke [21030085++] · Fri, 09 Oct 2009 21:48:58 -0400

Pressure Sensor and Rhodes Chroma CPU Plus (CC+)

Anyway, the Chroma will send poly pressure through the Syntech (which is what I have) and the CC+...

A quick note of clarification: a pressure sensor would be fully supported for local control of the Chroma, and the CC+ receives and responds to MIDI pressure messages from an external source, but it doesn't transmit poly aftertouch/pressure messages via MIDI today.

(xref: The Chroma CPU Plus (CC+): Firmware and the note "[Set Split 36] + P16 (Pressure Mode) - MIDI Pressure not tx'd (for either mode)"

Given the recent interest in the pressure sensor on the ChromaTalk list, this MIDI transmit feature will be implemented and will be available via an updated CC+ firmware image, available soon.

Arun Majumdar [21030348+] · Fri, 9 Oct 2009 23:33:25 -0400

Re: Pressure Sensor and Rhodes Chroma CPU Plus (CC+)

Hi David,

I have already bought your CC+ and am now looking at getting a third Chroma as a spare.

Please let me know when you update!

Now I think I need to get *two* poly sensors.

Arun Majumdar [21030348+] · Fri, 9 Oct 2009 23:36:47 -0400

Re: Pressure Sensor and Rhodes Chroma CPU Plus (CC+)

Also, as a note to Chris:

Please count me in for *** TWO *** full poly sensor kits.

Again, if you need to reach me, send me a private email at [email protected]

I can give you phone numbers and other contact infos since I am regularly in your area --- heck, tomorrow I am up at "Mills" in Annapolis ...

Please count me in --- if you need the money now, I am happy to provide it immediately --- we are such a small community and I am sure you are doing your very best :)

I bought a CC+ from David and I am ***soooo*** happy with it!

Chris Borman [21030194+] · Sat, 10 Oct 2009 08:43:34 -0400

Re: Pressure Sensor and Rhodes Chroma CPU Plus (CC+)

Thanks for that clarification David and great news you are going to add that feature!

Jesper Ödemark [21010135] · Sat, 10 Oct 2009 14:55:33 +0200

Re: Pressure Sensor and Rhodes Chroma CPU Plus (CC+)

It looks like the pressure sensor and the CC+ upgrade can finally make the Chroma my master keyboard. :)

Looking forward to all shipping info and maybe a video demo...

Chris Borman [21030194+] · Sun, 11 Oct 2009 01:18:54 +0000

Re: Pressure Sensor and Rhodes Chroma CPU Plus (CC+)

The Chroma has a special recognizable sound, no doubt. While He's at it, maybe David can add some Kurzweil 'key mapping' like functions beyond basic modulation. For example as I just described to my son today, light keying plays thunder, while a heavy key produces or triggers a lighting or thunder sound...

Dave Bradley [16330135] · Sat, 10 Oct 2009 20:44:11 -0500

Re: Pressure Sensor and Rhodes Chroma CPU Plus (CC+)

Chroma can already do this. Look at the velocity threshold trigger functions on the envelopes. Not bad for a 25+ year old synth!

Chris Borman [21030194+] · Sun, 11 Oct 2009 02:03:11 +0000

Re: Pressure Sensor and Rhodes Chroma CPU Plus (CC+)

The Chroma has a special recognizable sound, no doubt. While He's at it, maybe David can add some Kurzweil 'key mapping' like functions beyond basic modulation. For example as I just described to my son today, light keying plays thunder, while a heavy key produces or triggers a lighting or thunder sound...

...that would be the crack of the lightning sound (already had thunder). Basically using pressure to trigger stuff other than just plain old boring everyday modulation...

Chris Borman [21030194+] · Sun, 11 Oct 2009 02:21:46 +0000

Re: Pressure Sensor and Rhodes Chroma CPU Plus (CC+)

Chroma can already do this. Look at the velocity threshold trigger functions on the envelopes. Not bad for a 25+ year old synth!

A pressure threshold can be used to trigger another program?

Go to next message in "Pressure Sensor and Rhodes Chroma CPU Plus (CC+)" thread, December 2009

Daniel Rickenbach [21010172] · Wed, 21 Oct 2009 01:43:14 +0200

Hi Chris

any news about pressure sensor?

Marais · Tue, 20 Oct 2009 19:58:03 -0400

I have sent 2 emails to Chris expressing interest in the pressure sensor and more info and have no replies yet.

Go to next message in "Introduction and pressure sensor" thread, November 2009

Re: Almost all LEDs on...

Go to first message in thread, September 2009

Luca Sasdelli [21010226] · Thu, 01 Oct 2009 15:38:14 +0200

Hi Frank,

The only things you can check further, IMHO, are (in order):

  1. press the Reset button on new PSU PCB: the LEDs should go off and, in theory, you should get an autotune after 1-2s
  2. check +5V on SPSU terminal block: it's the digital section supply and it should measure around +5.10V; test the same voltage on a voice card (pls see schematic to find out a +5V DIG suitable point) and check that voltage drop is less than 100mV, so on ICs themselves, the +5V must not be below +5.00V (the range goes from 4.95 to 5.25V). Should the voltage be inadequate, you can adjust it with the small trimmer just close to the green LED inside the SPSU, near the +5V terminals
  3. check offset voltage on I/O board near the only one trimmer on it: adjust the trimmer to read the lowest value as possible
  4. take off all voice cards and leave just one in, then try again

Let me know what happens.

Three Chromas (and a Polaris) on eBay

Chris Ryan [21030691] · Fri, 2 Oct 2009 22:52:53 -0700

Item #270464632594: Current bid USD$200, ends October 9. "This Chroma is 100% complete and includes an anvil case. It was in storage for decades and recently discovered. It powers up but does not produce a stable sound. I opened it up and it was very clean inside. The battery had leaked onto one of the eight oscillator boards. The battery case was replaced with a new one. When I powered it up after the replacement battery, it went through its self-diagnosis and said that it had 7 operational 2/voice boards (out of 8). The membrane switches responed and latched/unlatched. Several weeks later I returned to the project. When I fired it up it behaved eratically. Everything lit up but I could not get it to produce sounds. I am not an electronics guy so I can't say much more, however I have a feeling that should be a straightforward repair for someone who knows what they are doing. I don't have the time or space to keep this one. It is in very nice cosmetic shape. The wood has a nice patina and is largely free of scratches. The metal has minor scratches but nothing big. All the plastic is intact and the front overlay is good (not mint, but very good). The keys are in great shape. There is no rust anywhere. The inside is very clean. It has never been exposed to wet conditions. Included is a large Anvil case with new foam. I am selling it AS IS."

Item #300353388923: Chroma and Polaris for parts. Starting bid USD$99, ends October 9. "These two vintage keyboards, hardshell cases (the Chroma has an Anvil case, the polaris has a non-name brand), and accessories were all purchased new in the mid-to-late 1980's by an amateur musician (myself). Both keyboards have been sitting in their cases in my home for the past 10+ years. Both were working before I stored them away; however I pulled them out recently and neither one powers up anymore (the Chroma does turn on but does not go through its normal power-up cycle). I don't know whether these are simply old fuses or something much less fixable - thus my suggestion that they are for parts. I am offering them along with their original cases, pedals, and accessories." The Chroma is serial number 21030857.

Item #170387036808: Current bid USD$1825, ends October 11. "The item is in amazing condition. It has been part of my vintage collection for a long time, but time have been tough lately, so it is time to let it go. The condition of the item - as stated in the auction title - is 'must see to believe'. Really gorgeous. Please, check out the pictures! The electronic condition is 100% working."

Chris Ryan [21030691] · Mon, 5 Oct 2009 22:19:29 -0700

Item #270464632594: Current bid USD$200, ends October 9. [...]

Item #300353388923: Chroma [21030857] and Polaris [302552] for parts. Starting bid USD$99, ends October 9. [...]

Item #170387036808: [Chroma 21030547] Current bid USD$1825, ends October 11. [...]

These are being bid up very quickly: currently USD$900.00, $810.01, and $2,425.00, respectively, with a number of days left on each. Note that I got the serial number back from the seller of the latter.

Arun Majumdar [21030348+] · Tue, 6 Oct 2009 10:04:24 -0400

It's a real deal to get a Chroma for under 2K! Even a broken one for under 1K! Anything can always be fixed ... and these are great instruments.

Chris Ryan [21030691] · Sun, 11 Oct 2009 23:47:42 -0700

Sold for USD$1626, $1757, and $3050, respectively.

Peter Forrest [21010096] · Mon, 12 Oct 2009 09:55:05 +0100

Thanks for the original heads-up, Chris. I ended up winning the Chroma and Polaris pair. Now I just have to get them back to England and then get them fixed - hopefully the Chroma with CC+ and poly aftertouch installed. That would put it up there with a CS-80, I reckon. Thanks as usual for the fantastic site.

Matt Thomas [21010021] · Mon, 12 Oct 2009 11:19:07 +0100

very good call peter. i know it's preaching to the converted but i think with the addition of the CC+ the chroma has become the big sleeper on the analogue market, way under value compared to other polys - and now with the aftertouch mod – wow :)

Peter Forrest [21010096] · Mon, 12 Oct 2009 11:49:12 +0100

It's actually got a nicer keyboard than the CS80, too... all good.

Musical Applications of Microprocessors

Chris Ryan [21030691] · Mon, 5 Oct 2009 09:36:48 -0700

This month I've posted an excerpt of Chroma-related material from Musical Applications of Microprocessors by Hal Chamberlin. I've wanted to add this to the site for years; thanks to Chris Borman [21030194+] for contacting the author, who kindly provided reprint permission, and for supplying scans of the relevant pages.

Chris Smalt [21010280+] · Mon, 5 Oct 2009 19:09:16 +0200

Cool. I briefly skimmed through it and noticed some typos:

"Also, man other strange effects are possible with lower Q settings."

"To permanently alter the displayed parameter value, another button must be pressed; otherwise it will rever to its previous value when another parameter is selected [sic]."

Chris Ryan [21030691] · Mon, 5 Oct 2009 22:13:35 -0700

Cool. I briefly skimmed through it and noticed some typos:

Thanks. They're now fixed.

Chroma VCO

Fredo Fraile [21040011+] · Thu, 8 Oct 2009 13:32:05 +0200

Hello Group, I need some help, which Chip is used for the VCO in the Rhodes Chroma? is it a 3374? or something different? hope someone can help, regards Fredo

Rob Belcher [16330123] · Thu, 08 Oct 2009 13:30:33 +0100

Im pretty sure the vco circuit is just standard off the shelf Ic's? The only rare chips seem to be the CEM 3350 vfc and the CEM 3360 dual vca chips, but there are no CEM chips used for the VCO.

Dave Bradley [16330135] · Thu, 8 Oct 2009 08:57:18 -0500

The Chroma oscillator is not a dedicated chip like the Curtis or SSM chips. It uses discrete parts. Article on the Chroma site explains it: The ARP/Rhodes Chroma VCO.

Fredo Fraile [21040011+] · Thu, 8 Oct 2009 18:12:44 +0200

Thank you for quick reply, that's what I thought before, I bought this Chroma 2 years before from a Guy from Sweden, told me that is only a 5 Volt Problem from the Psu, since that i bought a new Psu, a new Cpuboard, and then the repairguy told me that most of the boards are defective, i bought a couple of Curtis Chips for Filter and Vca, and now he tells me that the Vcos are dead, and I need Chips, feel like a fool, and this starts to get expensive, I am really frustrated about that, luck is I have a working one, thank for this Group, it is always helpfull, regards Fredo.

Luca Sasdelli [21010226] · Thu, 08 Oct 2009 21:37:48 +0200

Hello Fredo,

well... a "progressive" tragedy indeed :)

When I bought my Chroma (around 1989) it was a real mess; one of first faults were several OAs on voice cards: the original design uses some uA1458/4558, very popular at that time, but noisy and unstable; I replaced them with TL072, same functionality and pinouts, but they're JFET OAs, with high input impedance, very low noise and a more precise transition curve. A similar OA is used as Z14 (TL082), but older and a bit noisier than 072. Current street price around 0.38 Euros.

Dual Channel Board Schematic 1

They are Z4 and Z10. Should you replace them, please make use of shaped IC sockets. I don't know how they're called in english, but just as an example: this is okay this makes false contacts.

Find CEM ICs isn't easy; here some resellers:

Beware: they are very rare, people forces on this and you can find very high prices or minimum quantities. My suggestion is to replace them as the very last chance, i.e. after you have already changed everything on voice boards.

If the technician feels lost, maybe is better to get your instrument at home and, with LOT of patience, and only one voice card inserted, you can try to track audio signal across the voice card, to isolate the fault. Remember that all signal routing are done via CMOS switches, and if they're faulty, no signal will be on mixing lines. A simple and cheap CMOS switch, if faulty or incorrectly driven, could mute a complete channel

Good luck!

Fredo Fraile [21040011+] · Thu, 8 Oct 2009 22:12:13 +0200

Hello Lucca, thank you such much for your so detailed answer, I will send this mail to my tech, so he can check the information, and hope tht he use it, regards Fredo.

CEM 3360 on eBay

Chris Ryan [21030691] · Sat, 10 Oct 2009 20:14:00 -0700

Item #140351528950: three available at USD$49. Used for the VCAs on the Chroma.

Doug Terrebonne [21030114] · Sun, 11 Oct 2009 02:48:04 -0700

That was actually my auction. Arun bought all 3 I had listed but I have a few more.

Arun Majumdar [21030348+] · Sun, 11 Oct 2009 7:55:47 -0400

Yep - I have a second Chroma that I'm working on to get to tip-top shape ... or one has to have a spare machine to cannibalize for parts!

Re: Blue Box: Rhodes Chroma

Go to first message in thread, September 2009

Werner Schöenenberger [21010114] · Wed, 14 Oct 2009 21:47:31 +0200

Back from holidays so late answer (c:

Theo does not have a Chroma. But since I think I know the owner. Will try to check this.

Chroma Repair Question

Christian Kranz [21010146] · Fri, 23 Oct 2009 11:44:36 -0700

Hi,

i just subscribed to this list because i have a question:

I am trying to repair a Chroma for a friend (21010146). First i detected the leaky batteries and fixed it, than i found the power supply problem and adjusted it (thanks to the service manual!). Now i still have the problem that after switching on some LED's are constantly on. It does not responds to any input, 7-seg. display is not working (sometimes only on for a short time during power on).

I checked the CPU board, 16MHz clock ok, all address and data lines are toggling (reset# is high). The interface to the IO board seems to be o.k. All clocks are running, strobes on the IO_WR, IO_RD lines, address lines and data bus have pulses, only the X0_int signal level does not goes to ground but is maybe open collector.

On the IO board the keyboard scan CPU is operating. I see signals on all interface lines.

Power supply is clean and >4.9V on both boards.

I still believe there is a problem in the CPU board, or do you have other suggestions ideas?

Thank you very much for reading

Michael Grossman [21030350] · Fri, 23 Oct 2009 12:26:01 -0700

I suggest you verify connectivity to every device on the CPU board. The acid may have damaged some traces. I would start with the EPROM sockets.

Christian Kranz [21010146] · Fri, 23 Oct 2009 12:40:29 -0700

Hi Mike,

thank you for the replay, did that but no change. The PCB is o.k. I cleaned it with PCB cleaner and checked all the connections/wires near the batterie all is o.k. The damage because of the acid was not that big.

What i am thinking is that maybe one of the EPROM's is damaged/lost content after >25 years. Is that a typical problem?

Frank McGing [21010198] · Sat, 24 Oct 2009 00:26:39 +0100

What i am thinking is that maybe one of the EPROM's is damaged/lost content after >25 years. Is that a typical problem?

I am in a similar situation with my Chroma (21010198). Each time I boot it, a different combination of front panel LEDs come on and stay on, but it gets no further than that, and neither of the LED displays come on at any time. A tech friend checked all the EPROMs on his programmer, and they all appeared to be fine. Mine had no battery leakage at all.

I don't know what the 'typical' EPROM failure rate is - maybe someone else does?

Chris Borman [21030194+] · Fri, 23 Oct 2009 22:43:40 -0400

Not typical but certainly possible. Stray light through an uncovered EPROM window can erase bits and cause the micro to crash. You mentioned this occured before the PS swap.You might try re-seating all the socketed components on the CPU. Both the original and new power supply hold /RESET low until power is stabilized. Might also try a manual reset after power-up. No sure how the PS circuitry would react to that - Any suggestions out there?

Jesper Ödemark [21010135] · Sat, 24 Oct 2009 10:29:28 +0200

ch. kranz skrev:

What i am thinking is that maybe one of the EPROM's is damaged/lost content after >25 years. Is that a typical problem?

Not a typical Chroma issue AFAIK but I've heard of the problem quite a few times when it comes to Simmons gear.

Jesper Ödemark [21010135] · Sat, 24 Oct 2009 10:39:13 +0200

Hi Chromaboys,

to both of you with "christmas tree issues" on the Chroma. I'm no tech, but my Chroma failed on my prior to my PSU swap, with similar behaviour. If you plan to get the Chroma fully working and the PSU is the original I'd suggest a swap for the new one before searching for other issues. The voltage is critical and there are many parts depending on a clean and good voltage supply.

Just my two eurocents...

Christian Kranz [21010146] · Sat, 24 Oct 2009 08:27:34 -0700

Hi all,

thank you for the support, especial Chris. It was the reset circuit!

But i still have no sound. As i do not play this instrument, can someone give me a short hint what to do to get a simple sound out of it? After battery change my CMOS RAM is empty of course.....

For Frank: I believe you have a similar problem. I think it was a timing and voltage level issue on the reset line. I replaced both capacitors (C10 and C12, 33µ, 35V) and the output transistor Q12. Before i had slightly above 4V now i have 5 V at RESET# and a delay of maybe 2 seconds before the LED's start flashing.

Jesper Ödemark [21010135] · Sat, 24 Oct 2009 17:55:19 +0200

ch. kranz skrev:

Hi all, thank you for the support, especial Chris. It was the reset circuit!

But still... do swap PSU. It's just a question of time before it fails then.

There is a scratch pad function in the manual check for that. A bit messy, but it works...

Frank McGing [21010198] · Sat, 24 Oct 2009 21:14:47 +0100

I believe you have a similar problem. I think it was a timing and voltage level issue on the reset line. I replaced both capacitors (C10 and C12, 33µ, 35V) and the output transistor Q12. Before i had slightly above 4V now i have 5 V at RESET# and a delay of maybe 2 seconds before the LED's start flashing.

Great news about your Chroma, Christian! I think my problem is different though, because I've already installed a SPSU, so the power rails are all good. My Chroma was working until recently for the previous owner (with 5 voices tuned), but then crashed suddenly and has failed to boot since. It would seem to indicate component failure somewhere, I think.

Thanks for the suggestion though!

Christian Kranz [21010146] · Sun, 25 Oct 2009 07:45:51 -0700

Hi, it's me again with a problem :-(

i adjusted all oscillaters according service manual (oscilloscope and by ear is o.k.), auto-tune gives normally no error message back but i still have a problem...

All E and F tones on the keyboard sound most of the time the same (E). After approx. six times pressing F the correct tone (F) comes out but hangs. Several additional presses (with wrong tone) and the hang-up note (F) dissapears. That's the same in each octave, so a keyboard switch contact problem is unlikely?

Any idea? Also in overall the tones seems not to be well in tune..

Christian Kranz [21010146] · Fri, 30 Oct 2009 15:05:32 -0700

Hi, had some time today to look further into this and want to share my findings. I have the problem of the strange keyboard behaviour (see below).

So i connected a logic-anaylser to the CPU board and found that indeed the wrong keycode is delivered to the CPU from the keyboard scan computer.

In the next step i connected the logic-analyser to Port 1 of the 8039 keyboard processor and in case of the wrong keycode the output port is not stable but toggling between the correct code and the wrong code (LSB is not stable) during the keyboard interrupt. So it depends on the main CPU timing if the correct or wrong keycode is read.

No idea at the moment about the root cause of this problem...

Christian Kranz [21010146] · Fri, 30 Oct 2009 15:29:21 -0700

Problem found. The output driver of bit-0 of the 8039 CPU is weak and can not drive a stable signal. So i would need a new CPU but i guess i will fix this with a trick....

Chroma, Footswitch, Pitch Bend Assembly on eBay

Chris Ryan [21030691] · Sat, 24 Oct 2009 17:02:37 -0700

Chroma: item #170398356286, USD$1,700, ends October 30. "This Chroma was working 5 years ago. The power supply started acting up like they all do so I put it aside until I felt like buying the new supply. Well a little while back I found a new power supply on ebay for cheap. They said they bought it as a back-up for a studio in Ireland. I installed it. Before turning it on with all the wirers plugged in I tested the voltage and the 5.3 computer voltage read right but the 12/-12 voltage was not even, and I know it wont work right if the differ. So I guess you get what you paid for. So what im trying to say is you will need a new power supply 12/-12 5v the regulator board with all the right molex connector is fine thats the hard part to find or make. You can find the supply part at any electronic parts dealer. The chroma is in good shape has a couple nicks and small scratches. All the cards worked the last time is was used. Comes with damper pedal and cassette deck and cable. I could spend some time and get it going and get $3000 for it, but I dont have the time so Im letting it go at a fair price. These seem to be going up in value."

Footswitch: item #300360027747, USD$20.00, ends October 26. "It is a stereo type cord and the make/break contact is between the tip and thering. The sleeve must bee the ground connection. Not parts have been replaced and it was tested to work in the above described mannor."

Pitch Bend Assembly: item #300360028951, USD$40.00, ends October 26. "I believe no parts have been replaced and it the cable pictured is connected to the pots underneath. I see no reason that this should not work. Pleas email me if you want me to list specific Chroma parts."

Pictures from the auction:

Mal Meehan [21010182++] · Sat, 24 Oct 2009 20:56:38 -0400

Just to say this guy bought my 'brand new, still in the box, still in the plastic bag, never used' SPSU, that I bought from Luca but then, after selling the Chroma (as I moved to the States) I didn't use.

I kept it as a spare for my perfectly working Chroma, but once sold I ebayed it... he got it for half the price I paid for it and then complained that he couldn't get it working... I mean it was just as it was sent to me from Luca. Ok, so it was an early SPSU and if I remember there were a couple of mods that needed to be done to fix the sustain pedal polarity or something but I'm guessing there's not much wrong with this unit that a competent person couldn't fix - heck I might buy it off him myself, now that I am in the States.

Just annoyed with him for slamming a perfectly good PSU (I know how much time and effort people put into developing these new Chroma items) and for suggesting he got something 'duff' from me!!!

Chris Ryan [21030691] · Mon, 26 Oct 2009 22:55:56 -0700

Footswitch: item #300360027747, USD$20.00, ends October 26.

Didn't sell.

Pitch Bend Assembly: item #300360028951, USD$40.00, ends October 26.

Sold for $40.00.

Chris Ryan [21030691] · Wed, 28 Oct 2009 13:16:52 -0700

Chroma: item #170398356286, USD$1,700, ends October 30.

Sold for USD$1,350.00.

Go to next message in thread, November 2009

EPROMs on eBay

Chris Ryan [21030691] · Sun, 25 Oct 2009 18:17:26 -0700

Item #320430796496, USD$295.00, ends October 31. "This auction is for a rare, complete set of never-used EPROM upgrade chips for the historical CHROMA Synthesizer. They are Rev 14, and Rev 3 for the Keyboard Scan."

Picture from the auction:

Doug Terrebonne [21030114] · Sun, 25 Oct 2009 18:48:46 -0700

For a lot less than $295 you could buy an EPROM programmer and program your own using the files on the Chroma site...

Randel Osborne [21030467] · Mon, 26 Oct 2009 08:00:53 -0400

For a much better value, you could purchase a CC+!

Chris Borman [21030194+] · Mon, 26 Oct 2009 08:46:04 -0400

Now that is good advice!

Re: Hello all & Chroma repair suggestions needed

Go to first message in thread, August 2009

Heinz Weierhorst [21010276] · Wed, 28 Oct 2009 20:25:26 +0100

Hello Joel.

As you posted in august you need some help repairing a Chroma. First at all I can offer you my old CPU board for testing. Second I live in western Germany not much away from Belgium. So we can swap boards and check out what is wrong. If you want my help please contact me.

Kenton interface removal

Frank McGing [21010198] · Wed, 28 Oct 2009 19:30:39 +0000

Has anyone here removed a Kenton interface from a Chroma? I want to get rid of it in preparation for a CC+ (as soon as the next batch are produced), but I'm not sure if any traces had to be cut or components changed during installation. I'm also hoping that a simpler environment will help me to get my Chroma running again - the Kenton is a pretty messy install, and makes removal of the I/O board rather difficult!

I've had a look at the Kenton documentation on the Chroma site, and I can't see any trace cuts.

Matt Thomas [21010021] · Wed, 28 Oct 2009 20:35:12 +0000

Hi Frank

I removed one a couple of months back, it was about half an hour's work. the Kenton connects to the Chroma by wires soldered to the top of chip legs. I simply cut the solder joints as close to the chip legs as possible. After that it's possible to remove the Kenton boards and wiring intact - with the exception of the MIDI sockets in the back panel which are 'riveted' in place. The Chroma itself should shouldn't be damaged or need components changing.

Frank McGing [21010198] · Wed, 28 Oct 2009 21:52:17 +0000

Hi Matt

That's great news - thanks for letting me know!

new (soon to be) chroma owner; interested in CC+ board

RJ Krohn [21030455] · Thu, 29 Oct 2009 19:47:31 -0700

hi folks, im about to be a newly knighted chroma owner, as soon as my unit arrives from ebay seller. looking forward to it. ill register once its in my possession.

i know they are available from david on the list, but i figured i'd also throw it out there that if anyone has a [CPU Plus] board they are looking to get rid of, im in the market. i have a new PSU on order from luca, and will be delving into the machine in weeks to come! thanks-rj

Chris Ryan [21030691] · Thu, 29 Oct 2009 20:05:35 -0700

Welcome to the list, and congratulations on your purchase. I assume it was eBay item #170398356286? It would be great if you could report the serial number (and other info) when it arrives, for the registry.

RJ Krohn · Fri, 30 Oct 2009 13:46:46 -0700

yup, that's the one! will be registering when it arrives