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ChromaTalk Archives: January 2002

ChromaGraph Manual

Chris Ryan [21030691]

I've posted the manual for LaBach Software's ChromaGraph software for the Apple II. Though I never used it, I always though it looked like it did a nice job of representing the parameters in the context of the Patch setting. Screen shots are included.

Thanks to Ray Hannisian [21030829] for providing scans of this manual.

Has anyone else on the list used ChromaGraph?

Apparently no one had! There were no responses.

Happy 2002!

Service Center Recommendation

Mark Hauptschein [21030668]

I'm the original owner of a Chroma that just died after years of fanatical care. It won't power up -- just makes a sick pulsing noise. Voice card five was not working as well. Probably needs a new power supply.

Has anyone had recent experience with the service centers listed on the Chroma site?


David Clarke [21030085++]


I don't have any information to pass on (regarding the service centers), but the Chroma service documents are pretty good - and the insides of the keyboard are laid out in a relatively accessible way.

All that is to say, a general tech. worth his salt should be able to take the Chroma service info and repair the unit. If you know of someone geographically close then you might want to have it go there first (since the size/weight of the Chroma makes shipment sometimes difficult and/or expensive).

Rich Hilleman [21030351+]

I have a couple of Chroma's being built into one really nice one with a shiny new PS at CAE in northern california. The Chroma seems to be one of Peter's favorites.

The voice cards might be a problem as they are getting harder and harder to fix....

Fred Warren

I can recommend JL at MusicTek in LA [see Service for contact info]. He loves Chromas, owns both a keyboard and expander, has most of the old Chroma parts stock and REALLY knows how to work on them. He fixed mine after it had been dropped and died.

Rich Hilleman [21030351+]

JL is also great. He is my wave tech and rocks. I think he is alot of other people's favorite, too...

Voice Board Repairability

David Clarke [21030085++]

The voice cards might be a problem as they are getting harder and harder to fix....

This note got me to thinking. I had a gut feel that this really shouldn't be the case, but I have to admit I had never really looked into it before.

Being the curious type (and someone who doesn't have to go back to work until the 7th :-> ) I grabbed the parts list and a voice-board to try and see how hard/expensive it might be replace/repair parts of the board.

What I found was that pretty much everything is still available - and at quite reasonable prices. The only exceptions being the CEM3360 and the tempco resistors (the former being expensive, the latter being tough to find).

The PCB itself is only double-sided, so if worse really came to worse, the board itself could be easily rebuilt from scratch.

For what it's worth here's a (very) quick pass at the parts, at least one source of availability and a representative cost.

Qty Ref Where P/N Price Ea.* Price Ext.
4 C1-C4 Digi-key P4561-ND 0.111 $0.44

Desc: cap, 0.0068UF 50V 10%
4 C5-C8 Digi-key P4116-ND 0.43 $1.72

Desc: 100p (100k), 20%, 1kv disc
4 C9-C12 Digi-key P3480-ND 0.97 $3.88

Desc: cap. .022, 10%
5 C13,C14,C16-C18 Jameco 29831 0.07 $0.35

Desc: CAP ELECT 1UF 35V 20%
1 C15 Jameco 29891 0.06 $0.06

Desc: CAP ELECT 10UF 35V 20%
1 C19 Jameco 15528 0.05 $0.05

Desc: cap 470p, 20%, disc
5 C20-C23, C40 Digi-key P4569-ND 0.06 $0.30

Desc: cap .01, 20%, 50v disc
8 C24-C31 Digi-key P4569-ND 0.207 $1.66

Desc: CAP POLY FILM 0.033UF, 50V, 10%
8 C32-C39 Digi-key P4561-ND 0.111 $0.89

Desc: CAP POLY FILM 0.0068UF, 50v, 10%
2 C41, C42 Digi-key P4118-ND 0.419 $0.84

Desc: cap 150p, 20%, 1kv
2 C43, C44 Jameco 33486 0.25 $0.50

Desc: cap .1, 10%
2 CR1, CR2 Jameco 36038 0.04 $0.08

Desc: 1N4148
4 P5-P8 Digi-key WM3006-ND 1.458 $5.83

Desc: 8 PIN Molex, right angle
5 Q1,Q4,Q5,Q8,Q9 Jameco 38359 0.06 $0.30

Desc: 2N3904 NPN General
4 Q2,Q3,Q6,Q7 Jameco 38375 0.06 $0.24

Desc: 2N3906 PNP General
2 R1, R2 Jameco 94713 0.35 $0.70

4 R3-R6 $?.??

Desc: RES WW TC 1.87K 1W 3%
1 Z1 Jameco 12159 0.49 $0.49

Desc: CA3086
2 Z2,Z3 Jameco 29372 1.19 $2.38

Desc: RC4151D
3 Z4, Z10, Z29 Digi-key 296-1414-5-ND 0.8 $2.40

Desc: RC4558N
6 Z5, Z14, Z21-Z24 Jameco 33241 0.45 $2.70

Desc: TL082CP
1 Z6 Jameco 24281 0.29 $0.29

Desc: LM393N
1 Z7 Jameco 12634 0.19 $0.19

Desc: CD4011BE
6 Z8,Z9,Z11,Z15,Z17,Z18 Jameco 13119 0.39 $2.34

Desc: CD4052BE
1 Z12 Jameco 13127 0.39 $0.39

Desc: CD4053BE
1 Z13 Synthtech CEM3350 13.25 $13.25

Desc: CEM3350
1 Z16 Synthtech CEM3360 45.00 $45.00

Desc: CEM3360
2 Z19, Z20 Jameco 13098 0.39 $0.78

Desc: CD4051BCN
1 Z25 Jameco 13725 0.45 $0.45

Desc: CD4556BE
3 Z26, Z27, Z28 Jameco 44329 0.15 $0.45

Desc: CD40174BE
1 AP Circuits Proto 1 41.78 $41.78

Desc: PWB 11.15cmx33cm,
116 Resistors (general) 0.01 $1.16

TOTAL 131.89

* = unit price in USD, assuming a purchase of 10 pce's

With this thumb-nail estimate, it looks like an entire dual-channel board could be built from scrach, incl. PWB, (even in very small quantities) for about $130US.

If you take away the two most expensive items (the PWB and the CEM3360) and set aside the tempcos for the time being, then all other parts seem to be readily available, and only add up to about $40US.

Food for thought.

David Clarke

Fixed Chroma

Sandro Traversi [21010217]


Despite mydeep doubts to really fix it , I got it repaired ! Now it boots and shows 14 wonderful leds blinkings and really plays my 7 DCB

As I reported in previous mail ,my suspects were on Channel Mother Board (SHA circuit) or DAC and I was pretty worried about a DAC problem as harder to fix for an hobbist likeme. In fact, with no hope yesterday eveningI swapped IC Z2 (4175 - the decoder of the S&H addresses) and finally I got what reputed as impossible !

So, JLeon , I think that if you solved yours troubles swapping the I/O board , maybe that they dependedon DACIC (I was checking for an Intersil AD7541 - about $15) or on the I/O Strobe Decoders (Z39 Z40 Z41).

Now I'm gonna concentrating on calibration & trimmerings , then on fixing 8th DCB, then a Chroma Cult Midi I/O, and mostly PLAYING GOOD & WEIRD SOUNDS !

Jerry Leonard [21030100++]

Allright Sandro! Good for you. I will do what you did on my other board and see if I'm lucky enough to get the same results. Thanks for letting me know.

Fwd: Question about selling a Chroma?

Chris Ryan [21030691]

You can contact Matt at [e-mail address removed].

I have a Rhodes Chroma with a Flight Case. I just bought a Korg Triton ProX and am looking to sell the Chroma. The power supply is bad but I have the replacement for the "Nuclear Powered Chroma" modification. Basically I would like to know what it's worth "as is" or if I replace the power supply. If there isn't enough price difference, I may sell it "as is" but with the new power supply if someone wants to do the modification themselves. Also included is the MIDI Converter. It's external but it works fine. I have all the manuals as well as the Program print outs. The chroma also comes with a cassette recorder and pedals (volume, and dual pedal).

Let me know if anyone is interested and what your willing to pay. If the keyboard is worth much more with the replacement power supply installed, I may do the modification.

Matt Gerassimoff

looking for chroma editor

Michael Curt [21010112]

i'd like to buy the "chroma-editor" by oliver kirschning. but it seems as if mr. kirschning's e-mail address "[email protected]" is outdated. does anybody know how he can be contacted or does anybody want to sell me his/her copy of the program?

further i'm looking for the manual of the ees interface and/or users who use it sucessfully.

michael curt

(chroma #21010112)

CV/Gate ?

Sandro Traversi [21010217]

Hi all,

finally enjoying my swet Chroma, I noted it has no CV / Gate out (nor in) ...

Anyone knows how to get them out so to use Chroma as a master keyb to control analog modules or any V/Oct stuff ?

Dave Bradley [16330135]


Get the Chroma Cult MIDI interface, and then buy an Encore Expressionist MIDI/CV converter. It would be extremely hard to get gate and pitch CV information from the Chroma, because it's all generated internal to the computer.

I use my Chroma as the master kbd for my modular with this exact setup.

David Clarke [21030085++]

While is probably possible to pull the signals off from the inside of the Chroma (with a little work), the cheapest/easiest way to go would be use the MIDI OUT from the Chroma to drive an inexpensive MIDI->CV converter.

Fwd: Hi Chroma help

Chris Ryan [21030691]

Begin forwarded message:

From: Jeffrey Koepper [21030671]
Date: Fri, 25 Jan 2002 20:55:45 EST
Subject: Hi Chroma help

Hi Chris I am looking for a rhodes chroma as-is for parts. Either keyboard or Expander. Could u post that for me? thanks jeff

Source for Tempco Resistors?

David Clarke [21030085++]

A while ago I posted some information on the parts (and availability of parts) on a Chroma voice/dual channel board.

I had noted that 'tempco resistor was hard to find.'

Does anyone here actually know of a source for these at all (TC 1.87K 1W 3%)?

Sandro Traversi [21010217]

TomG usually sells PTC resistors, Axial Lead 1k 3000ppm type , but I don't know if they are good for Chroma VCOs ...