Posts Tagged ‘CS70M’

Yamaha CS70M Retro Fit

If you’ve been following the blog over the last months you’ll know that we organised a group buy of Kenton Retro Fits for the CS70. These had been long out of production but Kenton told us that if we had enough orders they would make a new design exclusively for us. So here it is, the fruits of our labour, a new Kenton retro kit fitted and working on a clients CS70M.


04 2010

Yamaha CS70m Kenton Midi retrofit group buy

Finally a way to realize the potential of the mighty CS70m!

You now have the opportunity to get a Yamaha CS70m Midi retrofit by Kenton Electronics UK. It will be a redesign of the Kenton kit that was discontinued due to parts availability quite some years ago.

Scroll down to the end of the document to read the specifications.

This is a group buy, which means that we need at least 10 prepaid orders to start the production. Production and distribution will be approx 8 weeks.


349 UK pounds + VAT which needs to be paid in advance to Analog Sweden. If we don’t reach 10 prepaid orders by the 1st of  November 2009, your money will be promptly returned.  Shipping cost not included.

Ordering & Questions

Use the contact form here

November 1, 2009

The kits are not intended for installation by the end user. They should always be fitted by an experienced synth engineer. The kits are built and tested before dispatch. DIY-kit NOT available. Analog Sweden can do the installation.

We at Analog Sweden have had a few enquiries about CS70m retrofits, so we got in touch with Kenton to investigate the possibilites for a new production run. Kenton wanted to have a group order to start the production, and here we go.
Analog Sweden is a studio and repair workshop in Helsingborg, Sweden. You can see what we do at

If in doubt, you can verify our claims if you get in touch with Kenton.


This retrofit kit for the Yamaha CS-70M adds the following MIDI control:

For incoming MIDI:

Any MIDI channel can be selected

Notes on MIDI note numbers normally 36 – 96 but transpose possible

Program change numbers 1 – 32
where 1 – 16 = upper + manual, 17 – 32 = lower + manual

Pitchbend -

Mod Wheel -

Filter cutoff frequency (of low pass filter)




This kit is to receive MIDI only, no MIDI can be sent, however a Thru
socket is included.

MIDI In, & Thru sockets
Push button (for programming the MIDI setup)
Setups are stored in non-volatile memory (Eeprom)

The kit comprises the following items
Circuit board -
Small pack – contains DIN sockets and mounting hardware
Large pack – contains cable assemblies
User instructions – How to change from default settings and general
Fitting instructions – step by step fitting guide plus diagrams of where
to connect what.

All kits are fully checked and tested before despatch.

Note: The retrofit kits are not intended for installation by the end
user. They should always be fitted by an experienced synth engineer.

Errors & Omissions excepted



08 2009

The CS70M Saga Continues

So the new caps arrived for the CS70. After fitting them and double checking their polarity it was time to reassemble the monster and power it up. It seemed to go well, the fault was gone? We were about to celebrate when 10 minutes later the reset problem returned.  I believe now that the problem lies with the CPU section since its fine in manual mode. I took a look in there and to be honest it’s one of those problems not mentioned in the service manual/troubleshooting notes. I hate to admit defeat since I’ve invested many hours in trying to get this thing up and running. But alas, it would seem for now the CS70 has beaten me. The CPU section has many (and I really mean many) IC’s any of which could be the cause of this behaviour. Its practically impossible to know what’s wrong. If anyone has any suggestions I’m all ears. Until then it’s only useful as a performance synth.

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03 2009

The British Empire was Built on Cups of Caps

A slightly mangled version of a quote from a very funny British movie. For those of you who don’t already know I’m actually English and cups of tea are part of my daily routine. Anyway back to the business at hand. All the caps have been removed from the CS70M power supply and I’m waiting for an order of new ones to arrive. Whether that will fix the problem remains to be seen, but as previously mentioned it was a job that needed doing regardless. In the meantime I took the second Prophet VS apart and removed the broken data slider and volume knob. An order for those parts is in progress also, so as soon as that arrives we’ll have two VS’s up and running. I also managed to take an inventory of all the missing knobs/parts of the remaining equipment in the studio, it’s quite some list, but then there’s quite some gear in there after all.


03 2009

Bust a cap in yo a**!

So I took out the control pcb’s and gave everything a good clean up. Lubricated the faders, wiped away years of dust, re-flowed a few solder joints and gave the cabinet and switch-caps a good clean. However I was unable to locate the cause of the reset problem, until I looked at the power supply. Looks like the caps are in need of replacing, one has leaked all over the pcb, so it’s time to make an order for new ones. This may not be the cause of the reset problem but even if not it’s a job that needs doing right away.

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03 2009

Phono wins! (almost)

Suck me!

Well I’m happy to report that I managed to resurrect the dead voice board in the CS70M. It was quite a task but with a bit of perseverance I finally found the fault. The oscillator IC was blown, replacing it with an identical chip from the old cs60 voice board made it sing again. Hooray! However another intermittent fault has reared its ugly head. The synth seems to “reset” sometimes when cold. Not sure what’s causing it, hopefully I’ll be able to track that down today and get the repairs done before the weekend.

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03 2009

Spaghetti Anyone?

So the CS70M has one dead voice, inside the case it’s a mass of wires. Luckily they had the foresight to add LED’s to the voice boards so that when you press a key you can see which voice is playing (or not). It actually has twelve voices, but they are dual linked so in use its six voice polyphonic. I found the dead board and proceeded to remove it. Now it’s just down to trying to diagnose what’s actually wrong with the board. I changed a suspect IC using a part pulled from an old CS60 board but unfortunately it didn’t solve the problem. Deeper inspection and troubleshooting is now needed. I’d really like to get this up and running.

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03 2009

Raising the Titantic

After some tests and exploration I was able to repair the broken key. So it was time to give everything a good clean up and put everything back together. Once it was reassembled I twisted Fredriks arm until he agreed to play us a demo. I grabbed the video camera and you can see the results. The next patient is a Yamaha CS70M,  this one might be a bit trickier to fix, time will tell.

Seems we forgot to turn on the gravity generator

Gravity is restored, Fredrik giving us another demo

A test of the internal sequencer


03 2009