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ChromaTalk Archives: May 2005

Power Supply Swap

Chris Ryan [21030691]

Sandro Sfregola has contributed an article on "How to swap the original power supply with a readily available switching unit," along with instructions on how to build high reliability prototype circuit board.

Thanks, Sandro!

René Hatt

Thank you for that article, which led me (maybe...) a step nearer to re-animating my Chroma.

My Chroma does not show any signs when I turn the Power Switch. Reading your articles, I wonder if this could be the total failure you mention when the Computer Board doesn't get enough voltage? In this case, is the Chroma absolutely dead, not even one light on (as in my case)? This would mean that I start with repairing the Power Supply, especially this +5V rail, as described in "Diagnosis & Repair".

So, to repeat the question that made me write all this: Does the Chroma seem to be ABSOLUTELY DEAD when powered on if the Computer Board doesn't get at least 4,84V?

Thanks & Greetings from hot (25 degrees Celsius) Switzerland

Werner Schöenenberger [21010114]

Hi René,

I think it cannot be definitely answered with yes or no. For sure the the voltage control is the first thing to check. As far as I remember I had a bad RESET circuit for resetting the microprocessor in my Chroma and this also lead to an "absolutely dead" behavior of the Chroma.

Cheers from hot Switzerland too ;-)

chroma on Ebay UK

Jesper Ödemark [21010135]

[Item 73195870]

Serial 21010094, so an early beast and yes, it's in the registry already!

Pictures from the auction:

David Gowin [21030611]

Reserve price 1,500 pounds sterling? That's almost $3500 Cdn! At the same time, hope he gets it, it looks like a well kept Chroma. (Hate to see what shipping charges to North America would be!)

Chris Ryan [21030691]

It is, sadly, Paul Hackett-Evans' Chroma. Remember Paul was looking for advice a couple of months ago on how or whether to keep his keyboard.

Jesper Ödemark [21010135]

1500 is fair if you check the european market...

David Gowin [21030611]

True enough, it seems their market makes pounds equiv to dollars in terms of purchasing power.

Jesper Ödemark [21010135]

The guy I bought my mini from has two Chromas he's planning to sell (still fishing for those serials) and he talked about 15000 SEK each (circa 1100 pounds) but that is is semi-miserable condition. I think one or two voices are dead, no midi interface etc...

Let's see what happens!

Paul Hackett-Evans [21010094]

Hi everyone,

Yes, it's mine.

I really don't want to part with my Chroma, but the realities of life are such that I have another 14 months to go at University, during which time I have very little income and I have to support my family somehow. My previous job is being "outsourced" to India, along with thousands more in the industry, so I'm retraining at University for a completely new career. I've managed for three years now, but it's very hard to keep going....

If I could find a way not to do this, I would. I know I'll never find another Chroma, and certainly not one that has been as well cared for. After the Chroma's keyboard action, any other synth keyboard feels like a bunch of spring-loaded plastic switches, horrible! I'll also miss the Chroma community.

The reserve is a little less than the Buy It Now price, but it's still fair for the condition and the work that's gone into restoring it to the condition it's in. In fact, the Chroma formerly owned by Glen Spalding, no. 21010100, was advertised for the same price, without MIDI and in rather suspect condition not so long ago by a dealer in the UK. I don't think I'm being unrealistic with the value, and I certainly won't part with the Chroma for less than it's worth. It's still priceless to me!

Even now, I'm agonising over whether to pull the ad from Ebay, keep the Chroma and head for a loan shark, or something.

I've had enquiries about my Chroma from as far as Athens and France. I guess I'll need to find out how much it would cost to ship there.

Does anyone know how much a Chroma with its footswitch, manuals and Chroma Cult Midiconverter in the flightcase weighs, please??


Jesper Ödemark [21010135]


Does anyone know how much a Chroma with its footswitch, manuals and Chroma Cult Midiconverter in the flightcase weighs, please??

I bought mine from Germany. Shipping with UPS (AFAI remember) cost in the region of 100-150 euros to Sweden. Weight was 60 kilos including original Anvil case, pedals etc. Hope this helps!

And remember - Parcelforce are the servants of the DEVIL! >:)

Paul Hackett-Evans [21010094]

Hi everyone,

I'm replying here to all the emails I've received following the ending of my Chroma auction, and I guess I'd better let you all know the answer to the question: what happenned?

At first glance, it looks as if the auction ended with the Chroma unsold. But if you look again, item no. 7319587019, you'll see that I ended the auction early, with 7 minutes to go. I've had a number of emails asking why, some from people who want to know if I still want to sell my Chroma, and some shamelessly trying to convince me that it's not worth a lot and offering to "take it off my hands quickly and cheaply". I'm glad to disappoint them!

Well, here's what happened. I know from experience that items like this usually get their real value bids placed in the last 30 seconds. I've watched enough auctions on Ebay to know this. Also, contrary to what one person tried to convince me, the market for vintage analogues is far from stagnant. There were 54 people watching the Chroma auction and I'd had more than 30 emails asking about it privately off ebay as well as the 8 who used the Ebay route. Three people came to see it and said they'd bid at the last moment to get the best price.

But, as you know, I've been in love with the Chroma for 22 years, and owned mine for 21. It spends most of its time in the flightcase, only coming out for University holidays. But I had it set up for the people who came to try it today, and as the afternoon passed, my son Alex and I were playing with the Chroma, "while I still owned it". I said to Alex that I was sad about selling the Chroma, and he said that he thought it was the wrong thing to do. He said "Daddy, you spent a year making the case and the keys really good, and Roy Paynter took 2 years to make it sound the best it could be, especially because he's our friend as well as a man who fixes Chromas. You'll never have another one like it. It would be really sad to let someone else have the good from all of that work." He's only 8 years old, but he understands matters of the heart.

The nearer the time came for the auction to end, the more I realised that after 21 years, I just couldn't sell it. The Chroma was a big part of my musical youth, and it brings me and my family a lot of pleasure to play with it now.

I just couldn't go through with it. Just couldn't. So I ended the auction with 7 minutes to go, before the big bids came in. I'm sorry to the people who emailed me saying they wanted to offer big money for it, but it was a decision of the heart.

I know that I'd have no trouble selling the Chroma now, but my family are supportive that it's too precious to me to let it go unless there's no other way. I'll have to find another way to raise the cash to get through University, but if I believe that it will all work out okay in the end, then hopefully it will.

Can I just say a sincere thank-you to the members of the Chroma list who emailed me privately to give their best wishes for the future. Let's see if I can't make it!

Chris Ryan [21030691]

That really made me smile, and even choked me up a little. I slept in my car once when I had little else, and my Chroma was in the trunk. You just can't put a monetary value on these things. A good decision--well done! And I'm particularly pleased Paul will continue to be part of this community.

Lars Johansson [21030632]


you made the right decision, trust me.

Money comes and money goes but a Chroma like that you'll never find again.

Jack Colburne [21030142+]

Yeah!! Boy, did that make me feel good!! Like all of us, I've been through some rough times and some good ones... ..and I've made right decisions, and wrong ones. ..but it's never wrong to listen to your heart when you have your ears open... or when you have an 8 year old to talk to.

Paul, please know that your son is a very wise man... that kind of wisdom that too often comes early and leaves as soon as we "mature". I get the impression that, for many of us, the Chroma symbolizes something... something we use to define or remind us who we are and, perhaps, where we come from. I know that there's much more tied up in my original Chroma that simply the sounds that I created, the wood of the keys, or the "voice architecture". (..I could go with a barrage of virtual synths and create pretty much any sound I need now.) Not to sound maudlin, but it reminds me of friends, my youth, a different life, and a different world of 20 years ago. It reminds me of relationships, decisions (right and wrong). And dreams... maybe even some that have not completely gone away.

Paul, please let Alex know that he is a very wise man and that he has made a lot of people smile. And has helped me make some decisions of my own. Bravo.

Jesper Ödemark [21010135]

So Lasse, didn't know you've found your way here... Have you checked the Chroma(s?) at work for serial? And have you heard anything from Anders regarding his?

Lars Johansson [21030632]

Oh, I've been here since 2002 06. Just haven't bought my own yet :-(

I'll check the serial and report and no nothing from Anders yet.

Jeff Bova [21030407++]


I'm very happy that you listened to your heart and not to the fears that come up that might have made you sell it. It was very inspiring to hear your story. Since the universe is perfect and in balance, I know that whatever you require to cover you and your families needs, will come from another source, It might even come from someplace totally unexpected ...............

Best Wishes,

Jeff Bova

Paul Hackett-Evans [21010094]

My thanks to everyone for all your kind words of support.

Jack, I think there's a lot of truth in what you said. I may be completely hopeless as a musician these days, but the Chroma is a tangible link to the way I lived my life for years. Now that I'm married and sensible, with kids and responsibilities, it's good to remember that I spent the '80s in the world of music.

I played in bands, toured, recorded and lived all over the place, pioneered a music technology course at music school, worked in the record industry, commercial radio and the theatre, ran a successful studio, produced artists, did gigs galore, made lifelong friends, lived an adventure and loved every minute of it.

Most musicians have an instrument that suits them perfectly. For me, that's the Chroma. I don't just love the instrument, I guess I love that it represents a special part of my life and the fun my kids and I still have with it. Probably something to do with the reasons why I couldn't bear to part with it.

Jeff, I'll hang on to your thoughts - it'll probably work out in a way I don't expect. I'll believe it and it'll be true.

Best wishes,

Chroma on eBay Australia for Third Time

Chris Ryan [21030691]

Item 7320717348. And this time there's actually been a bid entered at Australian $1500.

See Chroma on eBay Australia (February) and aussie chroma on ebay again (March).

Jesper Ödemark [21010135]

aussie chroma sold

Good to see it coming to Europe... anyone here who snatched it?!

Sold for Australian $2035.10.

Paul Hackett-Evans [21010094]

The Aussie Chroma's on Ebay again!

It looks as if the deal on buying the Aussie Chroma didn't go through, as the seller has relisted it.

See eBay item number 7325758836

Same starting price, 1500 Australian Dollars plus shipping.

Paul Hackett-Evans [21010094]

Re: aussie chroma sold

I'm not sure who it is, but the Ebay ID is one of the ebayers that was bidding on mine before I withdrew it. Obviously it's someone who's keen on having a Chroma, given that he or she will be paying to ship it from Australia to the UK.

Chroma replacement case

John Leimseider [21030434++]

After redoing Ron Joseph's Chroma [21030042] in Zebrawood, we're thinking about selling kits of all of the wood pieces, all precut, predrilled, and finished. Is anyone interested? We're open to suggestions for our next prototype... We don't want to do another in Zebrawood, but we were thinking of birdseye maple or some other light colored woods. Are there any requests? Please let me know... Thanks.

David Clarke [21030085++]

John - in order to judge how attractive this might be, would be it possible to give a ballpark estimate for cost?

Also - would you need to use parts from an existing Chroma (such as the wood supports for the front panel or the metal braces for the end-cheeks - or would these been included too?)

David Gowin [21030611]

Now that sounds like something I'd be interested in!

Stu Ervin

could this be done in a clear transparent lucite, like the old mosrite guitars? I wold be interested in that....

Jesper Ödemark [21010135]

(Homer Simpson mode on)
"Transparent Chroma... Mmmmmmm... *drewl*"
(Homer Simpson mode off)

John Leimseider [21030434++]

Hi David. On the 2 we've done so far, it's simply replacements for the outside wood, You use the same internal wooden blocks and metal pieces. The parts we did are predrilled and finished, it's just a matter of removing a few keys to get the front rail screws, and removing the other wood and screwing it back together. The price will vary from about $500 US and up depending on the type of wood.The Zebrano (zebrawood) was really expensive, but we're planning on some light woods, like birch or cedar and a really dark walnut. We don't want to do another zebrawood, because we feel Ron should have a one-of-a-kind piece. I'd really like to do a nice figured ebony for mine... I haven't decided yet, though. Thanks.

Vincent Russo [21030433]

A vote for a lighter natural OAk here John as you know, but thats a good chunk of change too. : (

Vincent Russo [21030433]

Tips/Instructions for taking wood off Chroma

Well JL's post has inspired us to have a local carpentry shop refinish our Chroma Wood pieces for us. Can others that have done this offer some tips on exactly what we need to do for taking the different wood pieces off the Chroma body please ? Is it easy to get back on ?

David Clarke [21030085++]

Re: Tips/Instructions for taking wood off Chroma

Depending how far you want to disassemble, the wood pieces are quite easy to come off.

On a Chroma (or Expander) there are 5 pieces:

  • 1 strip at the back of the lid
  • 1 strip at the front of the lid
  • 1 strip along the front edge
  • 2 end cheeks

The two lid strips are directly accessible once the lid is lifted up (i.e., lift the lid, and then remove the 3 or 4 screws underneath and the wood comes right off).

On the Chroma, the wood strip along the front of the keyboard is attached to a piece of "L" shaped metal. It is easiest to remove the metal + wood, and then once removed, separate the wood and metal (again, just a few screws). To gain access to the metal strip, just lift up on a few of the keys and find the few screws holding it in.

(If memory serves) the end cheeks are connected via a metal bracket (to the inside front of the case) as well as via 4 or 5 screws that go from under the Chroma, up through the wood base - and then screw into a wooden brace. (There's also an L-shaped support that goes between the two end-cheeks, but it's only 2 screws to remove those.

If you've got the room for it, the easiet thing to do just remove the lid, front panel and set the keys aside. That will pretty much give you full access to everything and will also make it easy if you want to lift up an end of the keyboard to get access to things (i.e., you won't have to worry about keys falling out, or control panels sliding, etc.)

The expander is very similar, except the strip of wood along the front edge is actually connected to the control panel (and, of course, there are no keys to have to worry about).

Small chroma question

Chris Ryan [21030691]

Kevin Lightner (, who is not on the mailing list, had a quick question:

Normally I'm at the other end of the question/answer thing, but I have one question for you. :)

I have a Chroma in right now. (actually two- both psu failures)

On one, I've completed considerable work and replaced the power supply, several ICs, all caps, etc. It's operating much better, voltages are correct, etc.

One thing though- if I move the parameter slider it locks up. No other slider, the tuning control, etc will do it. ADC is apparently fine. The display goes to some random display and nothing will affect it until powered down. Doesn't matter where the slider is placed when powered up. The movement of it from there locks everything.

This unit doesn't have the (#14 I think) service mod with the chip hooked up to the ADC though [probably Field Change Notice FCN2-004]. Think it will help?

Thanks for anything you can share.

If anyone has any ideas, post them here and I'll forward them on to Kevin or just send him the archive when it's posted at the end of the month.

Stu Ervin

could it be an addressing problem? when the cpu detects parameter change ( you moved the slider ) it needs to go to a particular routine in memory to service this event.... if the address lines were broken or bad memory chip at that location it would get garbage data and could hang.....

put a scope on the addres/data lines somewhere and see if the cpu gets stuck when you move the slider..

David Clarke [21030085++]

I'd certainly support this idea.

For Chroma problems I've seen in the past, when the synth seems to generally behave OK but then go off into the weeds a specific task is done, this has turned out to be a problem with code execution (exactly as noted above).

The problem could be due to acid damage to address/decoder lines on the CPU board - or in some cases I've seen, just old/sick/dying EPROMs.

Another problem I've caught myself on is that if you're debugging and removing/installing PROMs, it is easy to accidentally have one of the pins bend underneath (Everything will run fine into that specific area of that one PROM is addressed).

For the general debug - since there are two Chromas at hand, I'd use one to help diagnose the other. Swap the CPU boards, and confirm the problem follows it.

The socketed components (EPROMs, CPU, RAM chips) could then be swapped between boards to help narrow down the source of the problem.

Adding heat sink fins ?

Vincent Russo [21030433]

Any opinions if this would be helpful to the Chroma ? I was thinking adding a heat sink fin to back panel where is gets REALLY Hot. Does it needs to be wired to anything ?

Jesper Ödemark [21010135]

All I've ever heard is that if you change the PSU your home... mine haven't had any trouble since former owner changed the PSU...

replacement screws for front and top-back panels ?

Vincent Russo [21030433]

Anyone know what size these screws are so I can get replacements ? and even better would be a source and product #'s ?
Thx so much, Vince

PS Our Chroma went to the carpenter today to have the wood refinished this week. Dave Clarke, thank you for the advice on disassembly.

David Clarke [21030085++]

Anyone know what size these screws are so I can get replacements ?

The four along the front/top lid are bronze coloured screws with a 6-32 thread and an oval countersunk head-type.

The four screws holding down the front panel are black pan-head screws with a 6-NC32 thread (with a head size of approx 0.25"/6.5mm and an approx. 1"/26.5mm length).

The screws along the back of the top panel (9 of them) are round head with a 6-32 thread (black in colour).

(The screw sizes are quite common - and should be available at your local hardware store. That being said, it may be a bit harder to actually find the screw you want in the material you want i.e., finding the screws in stainless is probably easy - finding them in bronze/black might be a bit tougher. Slightly longer or shorter screws should also do the trick).

Vincent Russo [21030433]

Thank you Dave, Anyone know a good online fastener place btw?


Peter Carss

Greetings to the group

I have recently acquired a Chroma s/n 21030823 and expander s/n 0101. I'm really not interested in keeping these units, and one member here is really interested in buying the expander.

I don't know enough about them to test them out. The keyboard went nuts and blew a fuse when I turned it on . . . the expander front panel seems to work fine, except the autotune doesn't respond as expected . . . it just shows zero through 9 on the data display.

I believe I saw on the site somewhere that David Clarke, one of the Chroma experts, also lives here in Ottawa, Canada. I wonder if he would contact me for a little advice on this unit.

If anyone is interested in the keyboard section, which would include an Anvil case, they could contact me too, for more information.

Brian Silva [21030450++]


How much for the Keyboard? What condition?

Chroma Restoration Stage 3 (Refinishing & new hardware)

See earlier thread Chroma update (December 2004) for details on restoring the electronics.

Vincent Russo [21030433]

Hello All, Thought we would share our proud photos of the refinished Chroma back from the carpenter. The wood was removed, stripped, planed, sanded, then refinished with Minwax. Not the most perfect Chroma in the world, but we are very happy. The Ob Xpander was also given a new finish.

Was also able to add new hardware Screws, and ended up liking the silver better than black : )

Thank you to Dave Clarke, Chris, Don Tillman & JL for their advice and inspiration.

Vincent Russo [21030433]

Someone emailed me asking the cost of the project:

  • Can of Minwax $10
  • Carpenter time and labor $100 (yes he is a friend : ) (4 hours)
  • New screws/hardware, $5

Jesper Ödemark [21010135]

Nice woodwork!

If I should do that to mine it would look like new I think. Now it looks worn but the metal pieces are fine and unscratched...

Ron Joseph [21030042+]

When they refinished mine they also repainted the metal.I opted to replace the original screws w/ brass screws from home depot.

Ron Joseph [21030042+]

Looks great!!

Vincent Russo [21030433]

When they refinished mine they also repainted the metal.I opted to replace the original screws w/ brass screws from home depot.

I always have something on mine (xpander, Mini, Jupiter 4, JX-10, etc.) so didnt think it would matter. of course a Chroma Expander is what belongs *wink*


Marcel de Velde

[no message body]

Chris Ryan [21030691]

This seems like a good opportunity to remind everyone that mailing list instructions and guidelines can be found at the site. Note that subscription requests aren't sent to the list itself.