The M1 and DX7, becoming more desirable?

Although the ideal of Retroactivesynth is to keep the old analogue’s alive, more and more Digital synths appear for repair, and amongst the most popular recently have been Korg M1’s and DX7’s.

The reliability of the main electronic circuitry is excellent and remarkable for machines of this age but most of the issues with these Digital Synths are on the periphery, batteries buttons and sliders, broken keys and joysticks and pitch bend and mod wheels. Blown power supplies are not unheard of either!

In a lot of ways, Digital Synths are much easier to diagnose than their Analogue counterparts, as they mostly have diagnostic routines built into their Firmware, which is great as long as you have access to the relevent documentation which lists the keypresses necessary to access it.

Both of the above synths are well documented, and this information is widely available online.

It is the availability of specific parts that is the real issue with any Digital Synth, a now unobtainable slider, output sockets that haven’t been produced in 20 years and keyboard keys that are only obtainable from one of the breaker sites or on EBay as a Pot Luck endeavour.

Both of these synths actually sound very good, our own preference would be for the M1, but it has effects built in whereas the DX7 does not, strangely enough they both share the exact same keyboard mechanism, made by Yamaha and used in a lot of the M1’s successors including the 01W, Trinity, Triton and Triton Extreme.

We got another M1 in the last day or two with button problems. It was ostensibly just one but further testing found a total of 9 that we would regard as unuseable, and so they were replaced. They were mostly the 0-9 buttons in the numeric keypad which is to be expected. Thankfully the tact switches are still being produced by Alps in Japan and are still widely available, have them as do Farnell. The real hassle of replacing tact switches in any modern synth is that the whole machine has to be stripped out to get to the front panel switch board. If you can imagine how a modern synth is manufactured, production starts with an Aluminium extrusion, which is the front panel. Firstly the display is bolted in, then the button board with all the switches, followed by the keyboard assembly, then the output sockets board. Then the main board goes in and finally the bottom cover of the synth. So to get to a button board the whole synth has to be dismantled in the reverse order to how it was made.


It is not entirely necessary to remove all the connectors from all the boards to accomplish the task of replacing the tact switches, just a few have to be disconnected to allow enough leeway to swing the main boards out of the way.

The Korg 01W/FD

We bought one of these back in February as a workhorse MIDI controller for the workshop, it had issues with the dead backlight and several faulty keys, but all of these were sorted out and the display replaced by an LED backlit version which required some modification to the power supply board. The High Voltage transformer and the transistor circuits have to be removed from the power supply board and replaced by a simple 39 Ohm resistor attached to the 5 Volt power rail to power the new backlight.

Glossing over the simplicity of fitting a new display fails to emphasise the amount of hassle it takes to dismantle this synth to a position where you can fit it. Everything has to come out of this thing, and it takes more than 100 screws to do so, you are left with a long piece of Aluminium in your hand with the old display in it , and pieces of 01/W scattered all across the workshop, this synth has to be the most difficult disassembly of any synth we have worked on. The display colour is white on black, and as mentioned before, my camera doesn’t do it justice, as it looks a lot better than the photo.


Actually the keyboard repair was the most interesting part of the project. There were two broken keys which were replaced, but the interesting part concerned the so-called sticky key syndrome that the 01W is allegedly prone to. The 01W synth is according to internet folklore prone to having sticky keys, where you press a key and it might be a bit hard to press on the way down or perhaps even slower to come back up or release if it does at all.

We believe the issue is with what is the equivalent of the keyboard bushings on earlier synths. We have seen several synths in recent times which exhibited these problems, and we suspect that these issues are due to transportation or lack of flightcasing type issues.

The key guides under the keys themselves can get slightly bent out of position which makes the keys stiff to play and sometimes unable to release even under the springs pressure. The key guides are actually metal and part of the keyboard frame. but are covered by a plastic moulding and lubricated with grease. Careful bending with a big pliers will straightren them up and not break the plastic. The 01W has the reputation on the Internet as being the synth most prone to sticky key syndrome, but we feel this is unfair, we had an M1 last week with a sticky key, and this one was damaged in transit quite badly. The same keyboard frame is used in the DX7, the Trinity and the Triton range so all of these could suffer the same thing. Our 01W looks as though it spent its entire working life without a flightcase or even a Gigbag, so it is amazing how much of it was functional and let’s face it, it is over 20 years old. All the front panel switches still work as does the floppy disk drive.

Actually playing and programming this machine led to some interesting discoveries, the Waveshaping function is far more versatile and useful than Internet folklore would have you believe, the perceived wisdom is that it’s a fancy distortion control, but we got great mileage out of using the Waveshapers envelope functions to get some great PPG style digital sounds. As the 01/W is the only Korg synth to have this, it makes it a bit special. The successor synth, the Trinity, gained resonant filters but lost the waveshaper. The 01/W is a bit of a bargain right now, it is worth having a listen to and/or play with, as we suspect that it will be the next big digital synth to climb in value after the Roland D50 and Korg M1.


One thought on “The M1 and DX7, becoming more desirable?”

  1. One of my first repairs where I had to remove layers of boards was a korg M1. I had it in a storage unit during a move, and a big crt monitor fell on it from 6 feet up, smashing 10 keys. I took it fully apart several months later, taking tons of picks with my digital camera every step of the way. A bunch of stuff came up in life, so the M1 sat for 4 years completely disassembled. Finally I was able to order the keys. Luckily I was ale to locate the 4 year old jpegs, and though it took me a while, I was able to put it back together perfectly! So now whenever Im working on something, out comes the camera, its a life saver!

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