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ChromaTalk Archives: June 1999

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Chris Ryan [21030691]

Well, I guess this the first message to the ChromaTalk list. I assume everything is working, but it would be nice if you let me know that you received this (I've not set up a mailing list before).

We haven't exactly reached critical mass, but there are ten of us now.

I added a new page to the site [Chroma Cult mailing from October 2, 1986].

This is a letter I received from the Chroma Cult (Ken Ypparila [21030229])--exactly when, I can't recall, although it is dated October 1986.

It is interesting to note that the Chroma Cult offered several accessories, such as a memory expander and a breath controller mod, that I've not heard of existing on any Chroma. I have, however, heard rumours of one or more installed pressure sensors.

See A mod Chroma on Ebay.de, September 2003, for pictures of what is presumably the Chroma Cult memory expander.

What ever happened to Ken or KMX is a mystery; a web search turns up nothing. I bought the MIDI kit several years later, in the fall of 1989, and he was in Simi Valley at that point. It would be interesting to contact Ken now and get some more information about the Chroma and who participated in the Chroma Cult; I would like to know if he still has the ability to produce the MIDI retrofits.

Jimmy Moyer wrote to me in February with a phone number [removed] that he saw on a newsgroup in 1995. I haven't tried calling it. Anyone want to volunteer? I might be closest geographically, but I've invested a lot into this thing so far ...

I subsequently got in touch with Ken, who ended up making another batch of MIDI retrofits; see MIDI Retrofits: Syntech/Chroma Cult/KMX.

Chris Smalt [21010280+]

Re: Ken Ypparila

What ever happened to Ken or KMX is a mystery

Hi people

Ken emailed me on 22 Sep 95 to tell me that his interface was still available "for $300 US and I usually ship by mail overseas since the unit is small." I was looking for a second interface for my other Chroma, but never got around to ordering it... Since we're a more or less private group, I guess it's OK to post his address: [address removed]. I don't know yet if it's still valid, but I'll try soon.

Best regards

Chris Smalt

Chris Ryan [21030691]

Re: Ken Ypparila

I wouldn't mind trying him myself. I've posted a fair amount of his copyrighted material in the past couple of weeks. :)

Gabriel Katona

Hi There,

Got your page and it works. Ken Y. went on in the late eighties/early nineties to work for Fender. He designed a midi system that worked with stage lights. I have a Chroma with the midi retrofit and I have the memory expansion. Ken also updated my Chromas ROM from 12 to 14. He discouraged me from the pressure sensitive pad and breath controller because he said it didn't work well.

See Pressure Sensor Anyone? below for responses to this.

I still use my Chroma and it's in pretty decent shape. My Chroma (and I being the keyboard player in the band) were on the Starship tour from 1984 to 1987. I bought my Chroma at Many's in NY. I believe I e-mailed my story to you a while ago. It is amazing that my Chroma survived three rigorous years on the road traveling throughout North America and the Orient. It now resides in my studio and it's happy there.

Peace,

Gabriel Katona

Anvil Cases

Chris Ryan [21030691]

How many original Chroma owners do we have on the list? I wondered about pursuing replacements for the deteriorated foam in the cases that came with our Chromas. (Some of us also have damaged Chromas as a result, but I doubt that Anvil's lifetime guarantee would cover anything but the case itself.) I e-mailed Anvil a couple of weeks ago but didn't receive a reply. Perhaps if a few of us started making noises they'd notice.

Eirikur Hallgrimsson [21030467+]

Re: Anvil Cases, German MIDI adaptor

I have a case. I'd be willing to sell it. I don't expect to be shipping my Chroma anywhere. Yes, the foam did stick to the finish some while this particular Chroma languished in storage with the previous owner.

Eirikur

P.S. I followed-up the lead on that German external MIDI adaptor [Presumably EES]. They still sell them, but it runs about $500. I'm not interested at that price.

Chris Ryan [21030691]

I don't want another case like the one I've got. I want:

  1. a case that I can use (i.e. doesn't have deteriorated foam);
  2. a case that has foam that won't damage my Chroma; and maybe even
  3. compensation for the damage to my instrument.

David Clarke [21030085++]

How many original Chroma owners do we have on the list? I wondered about pursuing replacements for the deteriorated foam in the cases that came with our Chromas. (Some of us also have damaged Chromas as a result, but I doubt that Anvil's lifetime guarantee would cover anything but the case itself.) I e-mailed Anvil a couple of weeks ago but didn't receive a reply. Perhaps if a few of us started making noises they'd notice.

I'm not an original owner, but I would be interested in finding out of how best to get the foam replaced in my Chroma anvil case (and how much it would cost). Mine had deteriorated so bad that I really had no choice by to tear it all out - I now just have an empty box.

Dave Bradley [16330135]

RE: Anvil Cases & linked polyphony

I'm an original owner. My Chroma was damaged more by the case straps than the foam. I cut the straps out right away. My theory is that the finish on the wood was as much to blame as the foam.

I used to have an Expander that got ripped off, so here's a silly tip to get more polyphony from two linked Chromas, or a Chroma and an Expander:

  1. If it's a split patch, sacrifice one patch on each instrument to be silent, and monophonic. Set the split points the same, then Link Upper to the silent patch on one instrument, and Link Lower to the silent patch on the other. Now you have 7 note polyphony on either side of the split. I used to use this for my piano patch in the days before d$g%t*l samplers.
  2. If it's not split and you can use patch algorithm 1 without losing the character of the patch too much, copy B in one instrument into A of the other and set the patch algorithm to 0. Now you have 16 note polyphony.

Gabriel Katona

I still have my anvil case and replaced the foam. Although I have not transported my Chroma in 5 years, the case is still in good shape. Five years ago I brought my Chroma from Los Angeles to my new home in Franklin TN (near Nashville).

Chris Ryan [21030691]

Anvil Case Update

I received the following message today from Anvil:

From: "DW Root" <dave@rootintl.com>
To: "'Chris Ryan'"
Subject: RE: Lifetime Guarantee
Date: Tue, 8 Jun 1999 15:53:47 -0400

Dear Chris: Foam, being a petroleum product, deteriorates as a function of time. Heat can accellerate this process but it inevitably happens. It is not a Warranty covered item. We can sell you replacement foam if you like. I will need the inside wood to wood dimensions of both parts of your case and your item dimensions.

David Root

Call Root International, Inc. at 1-800-600-1953 PIN 2001 for ALL your shipping and travel case needs!

I guess they get to determine the terms of their "limited lifetime warrantee." I think they need to find an alternative to petroleum-based foam. Is it worth buying replacement foam? I wonder how many years it would last this time.

David Clarke [21030085++]

Dear Chris: Foam, being a petroleum product, deteriorates as a function of time. Heat can accellerate this process but it inevitably happens. It is not a Warranty covered item. We can sell you replacement foam if you like. I will need the inside wood to wood dimensions of both parts of your case and your item dimensions.

I wonder if they would have a record of the original Rhodes/Fender/Chroma order so that measurements wouldn't be required? I also wonder what sort of cost we'd be looking at for a replacement?

I guess they get to determine the terms of their "limited lifetime warrantee." I think they need to find an alternative to petroleum-based foam. Is it worth buying replacement foam? I wonder how many years it would last this time.

Has anybody ever used conformal packing foam inside an anvil case? You know - the stuff used to pack some electronic equipment from the manufacturer (they cover one side of the item to be shipped with a plastic sheet, and then fill up the rest of the box will an expanding/hard foam - then do the other side of the item. When finished you end up with two solid foam "moulds" the exact shape of your item - the foam being completely covered in plastic).

I don't know how well this would work - but the idea of a solid barrier (plastic) between the foam and the equipment would at the very least keep those smaller pieces of foam out of the insides of the gear ...

Tim Siefkes [21030850]

I, for one, have a Chroma that suffered the "foam rot". I've bought a bottle of Goo-Gone based on someone's recommendation I read on-line, but have not had the spare time to try it out yet. Looks like a big project!

Dave Bradley [16330135]

Dave mentioned above that his Expander had been stolen; I wrote him privately about this and he responded to the list.

From: Chris Ryan
Sent: Tuesday, June 08, 1999 11:34 PM
To: Dave Bradley

I've always thought that it would be (relatively) easy to recover something as rare as a Chroma Expander if it was stolen. There aren't a whole lot of them around. Or would a thief just trash it?

I lived in Columbus Ohio at the time. I even know who stole it - a crackhead that lived down the street. I searched the pawn shops in Columbis and Cincinnati for 6 months, but never ran across it. For all I know, he couldn't get any money for it and threw it in the trash!

Chris Ryan [21030691]

At 4:58 AM -0500 1999/06/09, tim siefkes wrote:

I, for one, have a Chroma that suffered the "foam rot". I've bought a bottle of Goo-Gone based on someone's recommendation I read on-line, but have not had the spare time to try it out yet. Looks like a big project!

I, too, bought some Goo Gone. If you're going to try this, make sure you do it outside! The fumes will kill you. That said, it definitely IS a big project; I haven't tried enough on my Chroma to know if it will really work that well.

Pressure Sensor Anyone?

Dave Bradley [16330135]

Gabriel Katona sez:

Ken also updated my Chromas ROM from 12 to 14. He discouraged me from the pressure sensitive pad and breath controller because he said it didn't work well.

Same story with me. I can't remember when I talked to Ken, it must be 1990 or so. He did insist that everything inside the Chroma is ready to accept a pressure sensor (POLYPHONIC!), and we talked briefly about the circuitry necessary to make it work. You can see a socket on one of the boards (maybe it's the CPU board) to plug it in.

I sure would like to figure out how to resurrect this project. Has anyone else put any thought into what it would take to make this work? Transducers are the major sticking point in my opinion.

David Clarke [21030085++]

Same story with me. I can't remember when I talked to Ken, it must be 1990 or so. He did insist that everything inside the Chroma is ready to accept a pressure sensor (POLYPHONIC!), and we talked briefly about the circuitry necessary to make it work. You can see a socket on one of the boards (maybe it's the CPU board) to plug it in.

The J22 socket on the I/O board has all the necessary points for the pressure sensor - there are 6 address bits (to select 1 of the 64 keyboard keys), +5v digital, digital ground, and +12v, +5v, -12v analog and analog ground.

I sure would like to figure out how to resurrect this project. Has anyone else put any thought into what it would take to make this work?

I really haven't thought about it too much, but off-the-cuff it would seem quite straightfoward - run the 6 address lines into a few address decoders (or just an inverter or two). The output of the address decoders/logic would drive the address lines on a eight analog muxes (like 4051 octal analog muxes). Tie the output of all the analog muxes together and tie that to the input of an op-amp. The output of the op-amp would go to J22-6/J22-13 (pressure sensor output). {the op-amp would be used to scale the overall output of the pressure pad output so that max pressure would be close to the max. allowable value on the system analog-to-digital converter}. If you can get 0 - 5V from the pressure pad itself, then you can likely do away with the op-amp (or just leave it in as a buffer stage).

Each key would have to have its own pressure sensor - and those would be hooked to the individual key pressure sensors (64 of them).

You'd be looking at 10-15 chips, at a total parts cost of $15 - $20.

Transducers are the major sticking point in my opinion.

I'd have to agree - you first need the transducer, then you have to worry about how best to mount them.

A monophonic pressure sensor would be a lot simpler - with only one long pressure strip required (under all keys). You could then ignore the address data and all the analog muxes.

Dave Bradley [16330135]

I really haven't thought about it too much, but off-the-cuff it would seem quite straightfoward - run the 6 address lines into a few address decoders (or just an inverter or two). The output of the address decoders/logic would drive the address lines on a eight analog muxes (like 4051 octal analog muxes).

Thanks for the explanation - that does sound familiar. So the pressure sensor address lines are continuously scanning in sync with the switch stack scans, or is something more elaborate going on with just selecting for keys known to be down?

I'd have to agree - you first need the transducer, then you have to worry about how best to mount them.

Not to mention the pain associated with calibrating for equal output at equal pressure at equal key depth.....

A monophonic pressure sensor would be a lot simpler - with only one long pressure strip required (under all keys). You could then ignore the address data and all the analog muxes.

This wouldn't be Nirvana, but it would be a hell of a lot better than nothing. You could probably even use a replacement sensor from a commercial ROMpler or something. Any volunteers to whip this up <g>?

Dave Bradley [16330135]

Actually, now that I think about it, the Ensoniq poly pressure approach might be a lot simpler to deal with ( serpentine tracks laid on a circuit board form a "pad" under each key, a metal plate attached under the key changes the capacitance by proximity effect ). I know they have this patented, but hey, we'd just be doing this in a noncommercial endeavor for private use, right<g>?

David Clarke [21030085++]

The Ensoniq method could conceptually involve less parts, but it would require either changes in Chroma firmware or a very smart external converter (or both) in order to have the individual capacitances "calibrated" upon startup and to convert the capacitance values into something that could be easily read by the Chroma ADC.

Anything is possible though ... :->

David Clarke [21030085++]

Thanks for the explanation - that does sound familiar. So the pressure sensor address lines are continuously scanning in sync with the switch stack scans, or is something more elaborate going on with just selecting for keys known to be down?

The note/velocity scanning is separate from the pressure scanning.

As far as I know, this is how things work:

When a key is pressed, the keyboard scanning computer (8039) will interrupt the main processor (6809). As part of the interrupt service routine, the main processor will read two 8-bit bytes from the keyboard processor - the first byte being a note number and the second byte being a time (equivalent to a velocity).

These two bytes are pushed on to/in to an internal FIFO (circular) note/velocity buffer and the interrupt service routine is done.

During the execution of the main processor's code, it periodically checks to see if the note/velocity buffer has anything in it (as well as checking the chroma port in/out buffer). If there is note/velocity data, then it pulls out the oldest (first in) note/velocity pair. It then checks to see if the key press was part of a "set split" command.

If a "set split" was requested, then the pressure is not read.

If it isn't doing a "set split", then it does a lookup on the velocity "time" and and generates a proper "velocity" value.

When it gets around to it, the Chroma grabs the note number of the "next" note to be played. This note number is written to the pressure sensor address lines (to "select" the key to be read).

So, I guess this was a long way of saying that the pressure is only read for those notes which are being played and it isn't being continuously scanned (like keypress/velocity).

unsolved problem

Wim Luijsterburg [21010034]

Since a few months I have an unsolved problem. If I leave the Chroma powered on after making music, after some time (say 10 to 20 minutes) and depending on the chosen patch, there starts a spontanious and continuing sound (as if the key is pressed and not released again). I have no idea where to start. The switch stack boards are OK and I have already checked the power supply.

Does anyone know a solution, or just a hint where to start?

David Clarke [21030085++]

A couple quick questions to help in finding the source of the problem:

  1. Do you have a midi interface installed (and if so, which one);
  2. Do you have anything connected up to the Chroma Port?
  3. Does it sound like the same sound each time, or is it different each time?

Jimmy Moyer [21030184]

Mine had a similar problem just in the last few months. Happily in my case, simply reseating the offending voice card solved it for me. That's the first thing I'd try. If that doesn't help I'd also look closely at where the edge connectors attach to the voice board. These are pretty flimsy and not too hard to insert misaligned. A connection may be broken there.

Wim Luijsterburg [21010034]

  1. Do you have a midi interface installed (and if so, which one);
  2. Do you have anything connected up to the Chroma Port?
  3. Does it sound like the same sound each time, or is it different each time?

Here are the answers

  1. At the moment there is no midi interface installed
  2. Nothing is connected to the Chroma port
  3. The sound is the sound from the chosen patch, as if eight keys are pressed simultaniously.

The continous sound stops (sometimes) after a key is pressed. Otherwise you have to do an autotune.

I hope these answers are of some help.

Dave Bradley [16330135]

Sounds like the CPU is getting glitched with a transient spike somehow. Power supply, power supply, power supply!

What's the voltage on your digital +5V supply? Should be about 5.05V - you need an accurate meter to read this.

David Clarke [21030085++]

I tend to agree with other responders.

My first check would be a reseat of the voice boards.

Secondly, my attention would go to the power supply. If it is the original power supply, a couple of those big electrolytic caps may be starting to dry out and letting a bit too much noise through. First check the voltage with a voltmeter per the level suggested in a recent post. Then look at the ripple on the 5V line to see if it is reasonable.

If the power looks Ok, then I'd start to look at the digital/CPU/memory circuitry (on the back-side of the membrane switches). Look to make sure there's been no damage from leaking batteries and look at the general condition of the boards, especially around the memory (RAM) chips.

Don Tillman

Hi. I finally got around to joining this list, so I'm coming up in the middle of this...

See if you can you reproduce this problem this way: Get one of those table fans, the popular 12-inch diameter two speed oscillating type that you're probably using now that the weather is getting nice, and plug it in to a socket in the same room as the Chroma. Switch the fan on and off a few times. Does that trigger the same effect? Especially turning the fan off? If so, the cause is likely those transient noise spikes on the line.

Chris Smalt [21010280+]

Hey Wim, how can we even begin to explain to someone from California what's the deal with Dutch weather? Don, you probably know they use mills in an effort to keep this country dry. Let me tell you: it doesn't work.

;-)

Jimmy Moyer [21030184]

One other thing to check in the power supply is the screws on top of the big filter cap. Make sure they are tight. Had loose ones that drove me crazy with all sorts of strange symptoms until I caught that.

Don Tillman

Hey Wim, how can we even begin to explain to someone from California what's the deal with Dutch weather?

I should explain that one a little better...

The motor in a fan is a classic inductive load, and inductive loads don't like sudden changes in current flow. Switching the fan off forces a sudden change in current by physically breaking the connection, and the inductive load reacts with a voltage spike arcing across the switch and inducing a voltage spike on the power line. So switching off the fan creates a classic transient spike on the ac line.

My Chroma often reacted to this spike, over 50% of the time, by playing eight random notes. That was one of the reasons I replaced the power supply with a modern switching unit. (http://www.till.com/articles/ChromaPowerSupply)

Question - Boot Problem

Jerry Leonard [21030100++]

Hello everyone.

My Chroma has been updated with a new power supply and all the voltages are correct.

Problem: when I turn it on, it boots up instantly, only blinks once. In the small LED display, it says 01234567 Supposedly the Chroma is supposed to flash eight times or so as it autotunes. Mine does not do that. I get no sound, and have put an o-scope on the output summing amp chip and it is pulled to ground, (muted, so no sound passes through, but is any sound being generated?) The main computer boots, because the Chroma will follow all the "set split" commands, such as battery voltage display, and all the other commands as listed in the programmer's manual and service manual. So, I know the main CPU function is working. I'm at a loss right now, it's not going through the autotune routine, and disabling all of the channel boards, so right now I'm quite sure the problem is on the I/O board, in either the computer interface section, or in the strobing circuitry. The I/O board has about eight different functions or sections, A/D, D/A, cassette functions, keyboard interface, etc. I have just a moderate understanding of electronics, so at present I'm stumped. Right now I want to know which section of the I/O board to focus on, then I can start replacing chips if I can't isolate the problem.

Any ideas anyone? I thank you for your help.

(It did the same thing with two old power supplies and a different channel motherboard and different EQ board, so the problem is definitely in the I/O board or less likely, but possibly, the master computer board)

David Clarke [21030085++]

Problem: when I turn it on, it boots up instantly, only blinks once. In the small LED display, it says 01234567

Remove and check all your channel (voice) boards. In particular, pay attention to the connectors and pins along the bottom edge of the card and look for any which may be bent back or not mating properly with the corresponding socket.

This may seem a strange thing to check, but a channel card with only some of its pins connected it can cause exactly what you're seeing.

Even if you don't find a physical problem, it would be a good idea to reinstall the cards one at a time and try to boot the machine each time (to see if a hardware failure on one card could be causing the autotune to fail on all cards).

Dave Bradley [16330135]

A different boot problem

I also have a boot problem but it's not as severe. About every 1 or 2 in 10 times I boot up, the Chroma refuses to run autotune and freezes with random LEDs on, and the alphanumeric displays blank.

Rebooting always works. FWIW, the power switch is usually left on, and power to the machine is switched from a power strip controlling other gear as well. Could this be a factor?

Russ Lyons [21030574]

With the Chroma's crappy PS design, boot problems are very common. My warning is, that if you have the original PS and you keep turning it on and off, it will either fry stuff and/or kill the supply permanently. Mine luckily just died. I replaced it with a similar supply that Don Tillman recommends. I recently fixed another Chroma that would lock-up on boot and light all the LED's, frozen. Cycling the power once, it would boot normally. I replaced two of the 10uF caps in the PS that the power reset fail depends on, and it fixed the problem.

Just and FYI,

Russ L

Jerry Leonard [21030100++]

Dave, I think I know what your problem is. Mine did pretty much the same as yours. I would bet it's the power-fail circuit in your power supply. I replaced mine with a new power supply and it would not work using Mr. Tillman's powerfail circuit. I had a tech replicate the power fail circuit exactly from the Chroma service manual, then built one from his schematic (which I can give you a copy of, if you wish to do this). The powerfail circuit is really quite simple with only 2 transistors and about 5 resistors. After I hooked it up and flicked the switch, it booted up every time. (but I still have my other problem) But I really think that's what's up with yours, in my opinion.

Jerry Leonard [21030100++]

I'll try it, thanks.

FS: Rhodes Chroma Voice Boards

Chris Ryan [21030691]

Saw this in usenet:

From "douglas tyler"
Organization jive boxes, inc.
Date Wed, 09 Jun 1999 14:35:25 -0400
Newsgroups rec.music.makers.marketplace
Message-ID <nsy73.86$gB5.170546@news.abs.net>

For Sale : Rhodes Chroma Voice Boards - $125.00ea. Tested and confirmed operational. 2 available. Other parts available also - request what you might need.

I've e-mailed him to ask him what else he has.

Chroma Cult MIDI Kits Available

Chris Ryan [21030691]

Ken Ypparila [21030229] has "3 or 4" MIDI kits (Syntech/Chroma Cult) available. He's lowered the price to $200 (was $300). I'd strongly recommend that if you don't have a MIDI upgrade (or if you have another, inferior kit), you should pick this up. It will probably be your last chance to get a decent MIDI retrofit for your Chroma. Ken says he "wasn't planning on making any more after these ones are gone." You can reach him at [obsolete info removed].

See MIDI Retrofits: Syntech for current contact information. Ken produced another bath of Syntech/Chroma Cult kits in 2001, and there are still some available. [August 2004]

Eirikur Hallgrimsson [21030467+]

Chris,

You're a godsend. I've sent mail to Ken to reserve one. Gee, I could then use the patches that I have archived in Galaxy format. I'll cheerfully make these available if it turns out I have banks that you don't. I'm actually excited about being able to save the patches that I have rather laboriously programmed into the beast over the past year or so. I got a couple of real keepers.

Dave Bradley [16330135]

Chris, any chance of getting Ken to join this list?

Chroma Program buttons not working

Tim Siefkes [21030850]

I recently (March 99) got my Chroma back from a couple of years in hibernation, had the power supply serviced, and all seemed well.

But now the last time I powered it up, the patch change buttons numbered 31-35 seem to have quit. No tapper, no program change, just seems dead. The rest of the Chroma plays fine, just that one set of five buttons have quit on me. Any ideas on what I can try short of taking it back into the repair shop again??

David Clarke [21030085++]

Did those buttons work at any time since you took it out of storage (hibernation)?

As for trouble-shooting, I guess it depends how much you want to muck about inside the Chroma - the straightforward checks are to ensure the connectors from the panel are well inserted and the "cable" material itself is not damaged or scratched - if everything else checks out OK, then you start to get into tracing the signal back to J14 and J15.

Buttons 31 - 35 are all on/scanned by strobe line -STB3. If there is a problem with connection on this line, that would account for the all 5 buttons becoming inoperative.

If you can't find the problem right away, and want to try to trouble-shoot it yourself and get stuck - don't hesitate to drop me note via e-mail.

Regards,

David Clarke

Jerry Leonard [21030100++]

The first thing that comes to mind is just a connection problem. Look on the I/O board where the grey ribbons connect and make sure they're fastened and making contact. I'll look at the service manual and try to be more helpful and have a better answer. However, I do think your problem will be relatively simple to solve. (famous last words)
JL