Of course, we offer more than you can see here. If you have any further questions, please contact us.
Finding faulty Voice Boards
The Chroma shows errors during tuning
If one voice voice is detuned, some sounds are distorted or sound brighter, then there is absolutely no reason for worrying. We have long term experience with Rhodes Chroma equipment and we can solve your problems quickly and efficiently. In the very most cases there is not any need for you to send the whole instrument. We need only the particular defective board which will be checked and repaired in our test system.
Rhodes Chroma´s voice architecture
The Chroma contains 8 voice boards which contain the electronic to produce 8 (double mode) or 16 voices (single mode). Therefore one board has two independent oscillators, filters and aplifiers as well as a complex modulation matrix to allow frequency modulation, ring modulation and oscillator synchronisation.
The most common way to realize an issue is the display output after tuning. If the Chroma was not able to tune e.g. card 2 and card 5 properly the display shows "ERR 25" and both cards are disabled - means that the synthesizer works with the remaining 6 cards and therefore the poliphony is reduced to 6 or 12 voices (depending on the used mode). The right hand picture shows the position of the particular voice board.
Sometimes all 16 voices are tuned properly but anyway there is something fishy going on: One oscillator sync does not work, a particular filter mode does not sound correctly or a voice suffers from a mellow and "indirect" sound.
With special commands you are able to find the defective card by yourself. Simply play the keyboard (one note at once) as soon as you hear the suspect voice. Hold the key and press <SET SLPIT> + <7> at once. This command disables the currently played note and the display shows the message "ERR 4" - if it is the card no.4.
There are several helpful commands:
- <SET SPLIT> + <6>: battery test, shows the battery voltage which should be more then 2,5 volts.
- <SET SPLIT> + <7>: disables the currently played voice; confirms with e.g. "ERR 6" for board #6
- <SET SPLIT> + <8>: shows all disabled boards, e.g. "0123" for the first four disabled boards
- <SET SPLIT> + <26>: disables all A-oscillators
- <SET SPLIT> + <27>: disables all B-oscillators
- <SET SPLIT> + <28>: enables all previously disabled oscillators
- <SET SPLIT> + <31>: special reset, tuning does not disable suspect voices
If you suspect a bad voice and do not want to find out the bad card then it will be easier for you to send us all 8 voice cards. We will check them in our testing system and write a comprehensive service- and status-report. Having all cards here we will service the card (e.g. chaning the old capacitors of the audio path; "recapping") which is a good idea anyway. after 30 years of operation. :-)
Removing the defective board
Power down the synthesizer and disconnect the power cable. You must not go ahead if you are not used to deal with electric equipment! Now remove the four screws on the upper side and the 9 screws on the backside. Please see the green arrows. CAUTION: The grounding cable is connected to the chassis with a bolt and a nut; red arrow. Do NOT loose this screw since this cable is essential for your personal safety. Open the top chassis and place it beside the Chroma so that the grounding cable is not disconnected or broken. Now you have unlimited access to the voice cards.
After removing the respective card, wrap it into antistatic foil first. If you need technical assistance or support, please contact us. The Rhodes Chroma is a very complex and sensitive device and should be treated with respect.
Other problems with your Rhodes Chroma?
Of course we can repair other defects fast and effectively, too. If you have any problem with your synthesizer, please contact us. We are happy to help you!
JL-Cooper MIDI Documents
This PDF manual is free of charge and you may download and print it for private use only! Special thanks to Georg Gabler for providing this manual!
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