Skip to content

Aurora - Switch Mode Power Supply for the Roland MKS-80

My lock-down project, Aurora, a replacement power supply for the Roland MKS-80, is now being built and tested.

Having just received the prototype PCBs only a few days ago, I'm currently assembling them and (very nervously) taking apart my own MKS-80. Please bear with me and I'll get up more information on this exciting project, as soon as I can.

What I can tell you is that Aurora comprises two PCBs, one of which sits on a special mounting plate. The prototype PCBs and mounting plate all fit into the MKS-80 perfectly, lining up snugly with the original PCB mounting studs. Also, the positioning and pitch of the headers is spot-on. That's important as the headers are soldered to the original PCB and are NOT push-on / pull-off connectors like say, the power supply distribution headers on the Roland MKS-70 power supply PCB.

MKS-80 power distribution headers line up perfectly on Aurora prototype Board A
MKS-80 power distribution headers line up perfectly on Aurora Board A prototype

So that's all a really good start. 🙂

I now need to know that Aurora properly powers the MKS-80; voltages are good including reference voltage and the power output of each supply is sufficient to drive the machine.

If you're interested in Aurora replacement power supply for the Roland MKS-80, then please don't hesitate to let me know.

Aurora will be available as a pair of populated PCBs and associated components, soon. Alternatively you can contact me to have Aurora professionally fitted into your Roland MKS-80. Prices will be published as soon as possible on my Prices page.

I often receive questions regarding the Roland MKS-80 output phase correction mod' and without meaning to do myself out of taking your money, I do feel it necessary to ask whether or not you actually need it!

Roland MKS-80 output phase correction mod at Plasma Music

Once upon a time, there were two conventions for delivering a balanced signal via a XLR socket. Both conventions (fortunately) used PIN 1 for earth (0 V). They differed however, in as much that one used PIN 2 for the positive (+), in-phase signal and PIN 3 for the negative (-) out-of-phase signal, while the other used PIN 3 for the positive (+), in-phase signal and PIN 2 for the negative (-) out-of-phase signal.

Back in the day, it was theorised that US and European manufacturers used the first convention while Japanese manufacturers used the second. In the eighties and nineties, I designed and built a lot of recording studios, live performance systems and guitar racks (remember them) and I can tell you that it didn’t really matter who built the gear, stuff was all over the place. You just had to check.

Polarity conventions of balanced signals over XLR connectors


Good question! Most of the time, you can actually ignore the convention used for sending a balanced signal to a XLR socket as it’s all ‘relative’. What I mean by that, is that if the output is from a synthesiser for example and you’re only using the balanced XLR outputs, then if the signal is ‘upside-down’, it’s only upside-down, relative to itself.

If however, you’re using the balanced XLR outputs from a synthesiser and the unbalanced jack outputs, then you will have a problem as the signals on the XLRs will be out of phase to the signals off the jacks. If the amplitude of both sets of outs is the same, you’ll get nothing if for example, when you mix the two together.

You can easily get around this by either phase inverting the respective inputs on your desk or DAW for one set of outputs or by swapping pins 2 and 3 in the XLR connections at one end (only) on the cable between your gear’s XLR outputs and your desk or DAW.

In a recording environment, it’s preferable to use balanced +4dBm so your Roland MKS-80 should only be connected to your desk, using the balanced XLR outputs. If that’s the case, then there’s no need to do anything.

Where phase becomes an issue is when signal processors are daisy-chained, like in the old massive guitar racks from the eighties or… (as previously mentioned) if you’re using both XLR and jack outputs.

You may just want everything to be as standard as possible in which case, things can be done internally with a very simple procedure. So, if you do want the Roland MKS-80 output phase correction mod', then please don't hesitate to contact me.

Roland MKS-80 output phase correction mod at Plasma Music

First attempt at making rack ears for the Roland MKS-80
Prototype rack ears for the Roland MKS-80 were collected this morning. I didn't get these anodised as I first wanted to make sure that they fitted properly. Pictures of the finished product will be posted very soon.

Following on from my last post 'RACK EARS FOR THE ROLAND MKS-70', I thought I'd better put this one up too, just to make it clear that I also have rack-ears for the Roland MKS-80.

As it tuns out, these rack ears will also fit the following Roland 2U modules:

  • Roland MKS-7 Super Quartet (released 1986)
  • Roland MKS-10 Planet-P piano module (released 1984)
  • Roland MKS-20 Rack mount version of the RD-1000 digital piano (released 1986)
  • Roland MKS-30 Rack-mount of the JX-3P synthesiser (released 1984)
  • Roland MKS-100 Rack mount version of the S-10 sampler (released 1986)
  • Roland DDR-30 Electronic drum module (released 1985)

Please note that these rack ears are only available in black and as a pair.

Like the MKS-70 rack-ears, these are made from aluminium with a back anodised finish on top of a horizontally running mill finish (just like the originals) and of course, they fit perfectly. They'll be supplied with eight black countersunk M4 machine screws.

I'm now happy to announce that these are available to purchase here. Just scroll down the page. or contact me for details on RE-MKS-80.

And finally, a BIG "thank you" to Lenton Engineering in Watford for delivering another precision job.


I'm deeply concerned about the environment and the exploitation of labour and so  I always use local manufacturers in preference to the Far East, with the following in mind:

  1. I can be confident that workers are treated fairly and earn a proper wage.
  2. I can be confident of the standard of quality of each item that is delivered to me.
  3. Communication is important and using local manufacturers, all correspondence is quick and understandable.
  4. I believe in supporting the local economy.
  5. I can be confident that the disposal of manufacturing waste is managed properly and in accordance with national and EU law.

Plasma Music uses local manufacturers

Using local manufacturers isn’t the cheapest option but the above points are important to me. I hope that they’re important to you too.

Prototype Rack Ears for MKS-70
Prototype rack ears for the Roland MKS-70 were collected this morning. I didn't get these anodised as I first wanted to make sure that they fitted properly. Pictures of the finished product will be posted very soon.

I've been meaning to do this for a very long time and finally, over lock-down, I decided to design a pair of rack ears for the Roland MKS-70.

I produced some plans from the rack ears of my own MKS-70 and this morning I got a text informing me that the prototypes were ready to collect. I didn’t bother getting these anodised as I wanted to be sure that they fit properly.

Well I have to say that I’m pretty chuffed with myself and Lenton Engineering in Watford. Always following my drawings precisely and consistently delivering perfect prototypes for me since 1985, I just love these guys.

Please note:

  • These rack ears do NOT fit any other Roland module
  • Only available in black
  • Only available in pairs

Made from aluminium with a black anodised finish on top of a horizontally running mill finish (just like the originals), these rack ears will be supplied with eight black M4 countersunk machine screws.

I'm now happy to announce that these are available to purchase here. Just scroll down the list or contact me for details on RE-MKS-70.

I've also designed a pair of rack ears for the Roland MKS-80, which again were based on the rack ears of my own unit. These are more versatile than the MKS-70 rack ears and fit several Roland modules from the eighties. Check out this post for details.


I'm deeply concerned about the environment and the exploitation of labour and so  I always use local manufacturers in preference to the Far East, with the following in mind:

  1. I can be confident that workers are treated fairly and earn a proper wage.
  2. I can be confident of the standard of quality of each item that is delivered to me.
  3. Communication is important and using local manufacturers, all correspondence is quick and understandable.
  4. I believe in supporting the local economy.
  5. I can be confident that the disposal of manufacturing waste is managed properly and in accordance with national and EU law.

Plasma Music uses local manufacturers

Using local manufacturers isn’t the cheapest option but the above points are important to me. I hope that they’re important to you too.

Impedance selector on Marshall 4502
The output impedance selector on the back of a Marshall 4502 JCM900 Dual Reverb 2 x 12 combo. Default setting is 8Ω as the two on-board 16Ω speakers are wired in parallel. Read more...

Guitar cab impedance and hence, connection can sometimes be a bit of a mystery but is critically important if for example, you’re using valve amps. That’s amps which have a valve power amp. If you have an amp that has a valve pre-amp section and a semi-conductor (transistor) power amp section, then it’s not a big deal.

Output Select on the back of a Marshall 2555
Keeping things simple; the output impedance selector on the back of a Marshall 2555 Silver Jubilee head. This amp is normally powering a pair of 16Ω 4 x 12 cabs making a total 'load' of 8Ω.


The valves in your power amp don’t connect to your cabs directly. Instead, they go via a transformer. The job of the transformer is to match up the output impedance of the valves to the input impedance of your cabs.

Impedance is like resistance. It’s even measured in Ohms (Ω). Unlike resistance however, impedance is different at different frequencies and so varies depending on the frequency at which it is measured.

To keep life simple, the impedance of a system is specified as an optimum, meaning that although the impedance changes as the frequency changes, the specified impedance is a particular quantity plus or minus so much. The impedance of for example, an 8 Ohm (or 8Ω) cab is roughly 8 Ohms across the used audio spectrum, plus or minus a bit.


Transformers in a vintage Marshall 1959
A vintage Marshall 1959 from 1972 with the back off, showing transformers. On the right is the mains transformer (near the mains socket). The transformer slightly to the left of centre, is the output transformer. The small transformer-looking thing that you can just see on the far left, used to be called a choke. It's basically an inductor used to help smooth out the mains. On a side-note, check out the old Bulgin mains socket.

If there is an impedance mismatch between a valve amp and its load (the cab that it’s connected to), the transformer in the amp is put under stress. This stress will burn out the transformer, your amp set-up stops working and you’re definitely in for a very expensive repair.

If the connection between your amp and your cab is broken and becomes what’s known as ‘open circuit’, then the same thing will happen. Effectively, your amp’s output has been set to drive a specific impedance. With nothing attached, your amp is trying to drive an infinite impedance; BANG!!!!!

Output transformer from a Marshall 10W head.
This is a blown output transformer which I removed a few years ago from a Marshall 100 Watt head. The amp was immaculate and the transformer 'looks' equally immaculate. Unfortunately a dodgy speaker cable was responsible for taking out this baby.


Like anything, it’s actually quite simple if you remember a few basics. For starters, it might be worth noting the following:

  1. Speaker cabs come in combinations of one, two or four speakers.
  2. Virtually all individual speakers in all cabs are 16Ω.
  3. The impedance of the cab itself, is a combination of the 16Ω speakers that are inside it. I’ll show you how to work that out in a minute.
  4. Once you know the impedance of individual cabs, there’s a simple way to work out the impedance of all the cabs connected to your amp.
  5. The last point is the most important; there are exceptions! While most manufacturers follow the rules and apply them to most of their amps, that’s not always the case. The Roland JC-120 is a classic example and I’ll show what I mean a little later.

So, let’s have a look at cabs. The simplest cab is the humble single speaker cabinet like a 1 x 12”, for example. With a single 16Ω speaker, the guitar cab impedance is (you guessed it) 16Ω.

A dual speaker cab will comprise two speakers of the same impedance (usually 16Ω). These will be connected in parallel. When resistors and impedances are connected in parallel, the combined resistance or impedance is worked out as follows:


'Z' is the engineering notation for impedance, so Zt is the total cab impedance and Z1 and Z2 are the impedances of the two speakers respectively. Of course since the impedance of the individual speakers is the same, the formula becomes quite simple, like this:


So to work out Zt (the overall impedance of our 2-speaker cab):


So you might have noticed that two speakers of equal impedance, connected in parallel, have a combined impedance of half of the impedance of one speaker... you have noticed right!

If you’re still with me, let’s throw in some numbers. Let’s start by remembering that our speakers are 16Ω each:


And of course, 8Ω is the correct answer! The impedance of a 2 x 12” cab comprising two 16Ω speakers is 8Ω. That’s because they’re connected in parallel.

Guitar speaker cab impedance explained - Two Speakers wired in parallel like in a 2 x 12 cab
Two speakers wired in parallel like in a 2 x 12 cab.

The combined impedance of series connected speakers (one after the other) is much simpler; you just add ‘em up. So if for example, our two speakers in the cab above were connected in series, then the combined impedance would be 16 + 16 = 32Ω. This doesn’t actually happen, well not to my knowledge.

Cabs with four speakers combine series and parallel wiring to achieve a combined impedance of 16Ω. Modern cabs have two speakers in series which makes 32Ω. Another two speakers in series which makes another 32Ω. The two pairs are then connected in parallel making the whole guitar cab impedance 16Ω.

Guitar speaker cab impedance explained - Four speakers wired in series / parallel like in a modern 4 x 12
Four speakers, two pairs which are wired in series, then wired in parallel.

You can of course do this the other way around; parallel / series, achieving the same combined impedance. In fact most vintage cabs are wired like this so two speakers are wired in parallel to make 8Ω. The other two speakers are also wired in parallel to make another 8Ω. Then the two pairs are wired in series to make the whole guitar cab impedance (8Ω + 8Ω) 16Ω.

Guitar speaker cab impedance explained - Four speakers wired parallel / series like in a vintage 4 x 12
Four speakers wired in parallel and then series. This is how a vintage 4 x 12 will be wired.

If you're not used to all that arithmetic, it can kind of look a little intimidating. On the hand, if you go over it couple of times, it will hopefully start to make sense.

So, cabs can be treated in the same way as individual speakers although cabs are usually connected in parallel inside your amp... err... with one exception (that I know of) and that the Roland JC-120. Firstly, although it's a combo the speakers aren't powered by one amplifier. There are two independent amps, one driving each of the speakers. Secondly and more relevant to this post, when you plug in additional speakers, they're actually connected in series with the internal speakers.

Remember that the JC-120 is a transistor amp so impedance matching isn't an issue. What it does mean however, is that the load on each amp, will increase when you plug in more speakers, thereby reducing the power output of the whole amp.

Remember that we worked out that 4 x 12 cabs are normally rated at 16Ω? Now consider using two 4 x 12 cabs to make a full stack. Plugging them both into a single amp where they are connected in parallel inside the amp, will make the overall speaker load, 8Ω, just like our very first 2 x 12 example.

2 x 12 cabs work in the same way. Each 2 x 12 cab is 8Ω. Connect two of them to a single amp and the combined overall impedance will be 4Ω so you need to set you impedance switch on the back of your amp, to 4Ω.

As with most things in life and as I've said a couple of times in this post, there are exceptions. As I say, the nice thing about standards is that there's so many to choose from! 🙂

Now then, pictured below is the back of a Marshall TSL122 100 Watt 2 x 12 combo. So is this confusing or what? For starters, the speakers in this thing are different.  Marshall decided to combine a Celestion Vintage with a Celestion Hertitage. Yeah, I know people do that but I'm not a fan, to be honest. Anyway, the point is that each speaker is 8Ω. On top of that (and the second point), is that they're wired in series to create 16Ω. Well that kind of makes everything I've just said, seem like a complete and utter waste of time.

Back of Marshall TSL122

On this particular amp, the on-board speakers are plugged into the (default) 16Ω speaker output, the markings of which are obscured in the picture, by the lead. Plugging into this socket, disengages the other sockets. If you want to use external cabs, you need to unplug the lead going to the on-board speakers, plug into one or both of the other sockets and if your cab impedance is 4Ω or 8Ω, you'll then need to select your impedance appropriately. If you've got a 16Ω cab, you have to unplug the lead going to the built-in speakers and plug your cab into the 16Ω output. That's really confusing and personally, I can't see a way to use the on-board speakers and an extension cab!

I'm not a fan of the TSL series but this kind of thing really makes me back off!

Then there's the Roland JC-120 which I've mentioned a couple of times, earlier. Not a valve amp so impedance isn't at all a big deal but... it's rather interesting that anything plugged into the speaker jacks around the back, is put in series with the on-board speakers. You have to remember that this thing came out in 1979, so what was Roland thinking? On the other hand, who'd want to mess with the sound that comes out of a bog-standard Roland JC-120? It's gorgeous!


So the bottom line is that you need to always check. Read anything that's written on the back of your amp and on the back of your speaker cab. Make sure that you read the manual and if you do get stuck, then you can always just call me!

Oh and one more thing;


One subject that comes up time and time again is "how to connect a USB MIDI keyboard to MIDI hardware". I've therefore decided to put up this post...


It's not exactly difficult but at the same time, you can't take it for granted that the MIDI keyboard you've got your eye on, actually has well... MIDI ports. Just about every controller seems to be designed to plug straight into your computer and hence, only has a single USB port. Manufacturers tend to offer their controllers in versions with those little 5-pin DIN sockets but they're usually upgraded versions with for example, seventy-six keys instead of the sixty-one keys that you wanted and perhaps more to the point, the version that'll fit on your desk or that's within your budget.

USB MIDI keyboard but no 5-pin DIN MIDI sockets
Oh! No MIDI port.

In a market that has been increasingly dominated by computers, some might concede that it's hardly surprising that MIDI ports are omitted from modern (MIDI) controllers. On the other hand, for those of us that have a collection of hardware sound modules, synthesisers and drum machines, MIDI controllers without MIDI ports is kinda useless!

Fortunately there's a potentially very simply and cost-effective work-around; introducing the MIDI USB host!

So a MIDI USB host is basically a small box running embedded firmware that recognises any class-compliant USB MIDI controller. That middle bit (class-compliant) is really important. A MIDI USB host is designed to be switched on and left. There's no monitor, QWERTY keyboard or mouse attached and there's no way to access the 'operating system'. It stands to reason therefore, that connecting anything to it, should be immediately recognisable and that means that anything connected to it MUST be class-compliant. Well, fortunately most USB MIDI keyboards are just that but it's always worth checking.

Several manufacturers make MIDI USB hosts but perhaps two of the most well known are those made by Kenton Electronics and MIDITech. Be expected to pay about 85 GBP for the former and 66 GBP for the latter.

For the DIYers amongst us, I've chosen to include the USB Host Controller Board V2.4 in the image above. Available from for a modest 16.20 GBP (at the time of writing), this kit is available in a variety of 'pre-blown' versions, with appropriate firmware put on to the 24FJ64GB002 microcontroller before it's sent out. One version makes this little board into a great USB MIDI host. You'll need to connect 5-pin DIN sockets, provide power and box it up yourself but for anyone who feels a little adventurous, this can be a very cost-effective solution.

One point worth noting, is that these boxes require power and both examples mentioned above are equipped with USB power ports that are secondary to the USB port that's used to accept the connection from your USB MIDI keyboard.


A company called iConnectivity makes a series of MIDI interfaces that are superbly designed and particularly suited for the modern audio production environment. The MioXL for example, has ten (yes TEN) USB MIDI ports as well as a bunch of conventional 5-pin DIN MIDI ports and... it also supports RTP-MIDI via a RJ-45 connection. Fully configurable via software hosted on your computer, the MioXL also has an elegant OLED display providing an array of status information. Available for under 350 GBP, this is a seriously powerful interface that's designed to connect to just about anything that can carry MIDI.

iConnectivity MioXL - The Mother of all MIDI Interafaces
iConnectivity MioXL - The Mother of all MIDI Interfaces. WOW!!!! I'd love one of these!


Anyone working with digital audio will be familiar with something called 'latency'. Loosely defined as the time between a signal entering a digital system and leaving the same digital system, latency is basically the time taken to digitally process a  signal. If that means simple analogue to digital or digital to analogue conversion, then even that process takes a finite period. This is not the case with analogue electronics although there does exist an almost analogous parameter called 'propagation delay' but let's not confuse things just yet, eh?

When working with computers specifically, latency can be quite substantial as there's a lot going on in these boxes that we've all grown used to. Having said that, clock speeds and more efficient processing both in software as well as hardware, has reduced latency over the years and in most situations, it's not a real concern anymore. On top of that, manufacturers of audio interfaces introduced 'direct monitoring' a long time ago which was and still is a great work-around to the issue of latency.

So going back to our USB MIDI host, it should be noted that by design, the smaller  boxes are very simple and are designed to do one thing and one thing only. Hence, while latency technically still exists, simply by the nature of the beast, it is negligible. I use a Kenton Electronics MIDI USB host myself and I can assure you that if latency was an issue, I simply wouldn't bother.

Following on from my post covering the installation of a replacement power supply into a Roland MKS-70, I decided to do another post on a whole bunch of cool Roland Super-JX Upgrades which I discovered during lock-down 2020. Apologies if some stuff is kinda repeated.

Back in April 2020, I got a Roland MKS-70 in for repair. It was powering up but wasn’t booting. While replacing original components that were over thirty years old on the power supply, another MKS-70 came in with err… power issues.

This all happened during lock-down so progress on the repairs was kinda slow. I did however, have lots of time to see what I could find on-line.

I very quickly came across and over a period of days, got to know Guy Wilkinson, a vintage synth enthusiast with a very relevant background. Guy has developed a switched-mode power supply for the JX-10 and MKS-70.

Guy Wilkinson's switched-mode power supply installed intoa Roland MKS-70
A P0004 switched-mode replacement power supply installed in a Roland MKS-70. Look... no transformer!

Guy also supplies a variety of displays, one of which particularly caught my attention, the Super-JX OLED upgrade display. As many Super-JX owners will know, the original vacuum fluorescent display (or VFD) as well as the FIP coil that drives it, is just about impossible to get hold of now. VFDs and FIP coils fail, so any potential replacement is well worth checking out, especially if it's going to be OLED cool.

Roland Super-JX upgrades - Guy Wilkinson's Super-JX OLED upgrade module
Guy Wilkinson's Super-JX OLED module.

I've always wondered why some people use the adjective "sexy" to describe tech'. Guy's Super-JX OLED looks stunning and now I know. I just can't stop looking at it! 😛

Super-JX OLED upgrade module installed in Roland MKS-70

As I continued my research into the world of Roland Super-JX upgrades, I came across and the Vecoven PWM upgrade; a kit which provides the Super-JX sounds with pulse-width modulation. WHAT!?!?!?!

Fred Vecoven sells the PWM upgrade as a self-assembly kit comprising two small PCBs (one for each voice board), lose components, three EPROMs and two replacement 80C320 processors (again one for each voice board). An option to buy populated PCBs is also available.

Neither the self-assembly kit or the pre-assembled PCBs kit are however, supplied with cabling or connectors, presumably because there are several potential mounting options. Guy's website has detailed installation instructions for Fred's PWM kit, both for the JX-10 and MKS-70.

Below is a pair of Vecoven PWM upgrade PCBs which I have made up myself.

Roland Super-JX upgrades - Vecoven PWM kit.
Assembled PCBs of the Vecoven PWM upgrade for Roland JX-10 and MKS-70.

The keen and eagle-eyed will have noticed that the ICs aren't soldered directly to the PCB and that instead, I've chosen to use turned-pin sockets; always a good idea!

Fred Vecoven has also rewritten the Super-JX firmware and has developed a flash upgrade module which, apart from increasing the memory to the equivalent of thirty-two Roland M64C cartridges (yes, that's right... 32 x M64Cs), allows firmware updates via MIDI. Fred's firmware also gives you some control over how Guy's displays work. Hey, is that teamwork or what?

Roland Super-JX upgrades - the Vecoven Super-JX Flash Module
Vecoven Super-JX flash module (highlighted in red) installed in a Roland MKS-70.
Vecoven Flash Module Installed In Roland MKS-70
Voice boards lifted for a close-up view.

Well it just so happens that I also have a Roland MKS-70 (yeah, I know... you're really surprised, right?) and all this stuff just sounded soooo exciting. Within a few days, I ended up with a switched-mode power supply PCB and an OLED kit from Guy and a PWM kit and a Super-JX flash module from Fred. My wife wasn't happy.

And I thought lock-down was going to be oh soooo boring!

I had to buy all the components for the P0004 power supply but conveniently, Guy has a very detailed bill of materials (BoM) on his website. This made components purchase very easy. The OLED module came fully assembled and Guy e-mailed me instructions on how to install it. As previously mentioned, Fred's PWM kit doesn't include connectors and cables so I also had to buy some bits to get this going.

Getting to know Guy and Fred was a privilege. In fact, I eventually struck up a deal with Guy and I am now offering ready-built versions of his P0004 switched-mode power supply board, as well as an installation service for this fantastic upgrade and his Super-JX replacement displays.

Click here for my prices.

If you're fitting the switched-mode power supply module yourself and your MKS-70 or JX-10 has a 2-pin IEC mains input socket, then you must replace it with a 3-pin IEC mains input socket. The replacement switched-mode power supply MUST be connected to earth as must the chassis of your Super-JX.

I offer a comprehensive earth bonding kit comprising the following:

    • 1 x IEC 3-pin chassis socket.
    • 3 x pre-cut heat-shrink strips.
    • 1 x insulating boot for IEC socket.
    • 1 x M3 earth tag.

2-pin IEC mains input socket to 3-pin IEC mains input socket conversion

It is paramount that if fitted, a 2-pin IEC mains socket be replaced with a 3-pin IEC mains socket and that the chassis and the P0004 are connected to earth.Installing these Roland Super-JX upgrades into my own MKS-70, was hard work but I had a lot of fun doing it and... I got to know a couple of seriously intelligent dudes.

My humble contribution to the awesome work that Guy and Fred have done, is a simple bracket which makes mounting the PWM boards into a MKS-70 a little easier. IMPORTANT: Since the bracket secures to the transformer mounting studs, it can only be fitted if Guy's P0004 switched-mode power supply is also installed.

Custom mounting bracket for Vecoven PWM mod for MKS-70
Custom mounting bracket for Vecoven PWM kit in Roland MKS-70. The benefits of using this include no holes to be drilled in the voice-boards, makes general maintenance so much easier and of course your MKS-70 can be put back to factory any time.
Custom mounting bracket for Vecoven PWM mod for MKS-70 installed
An elegant solution (even if I say so myself), my custom bracket makes installing the Vecoven PWM mod into the Roland MKS-70, so much easier.

The IDC connectors I've used, don't have the tidy fold-over clamp (retainer). That's because those ones are too high and this neat little mounting solution won't work as the whole assembly will simply be too high to fit in the MKS-70's 2U case.

I wasn't going to offer this bracket as an item as it didn't seem worth it but I've been persuaded to get some made up and so I’m selling them with fixing hardware (screws, washers, spacers), as a kit for 22 GBP. If you fancy one, you can either buy now from here or just message me.

Note that the bracket isn't necessary when fitting the PWM kit into a JX-10.

Inspired by Guy's switched-mode power supply, I've proposed a couple of joint projects so watch this space!


These machines are over thirty years old. As such, nuts and screws have seriously bedded in. You may find some glue around the nuts and even some signs of corrosion.

If you're upgrading one of these machines yourself, please take care when undoing nuts and screws. The studs which secure the massive heat-sink plate of the original power supply and also the transformer for example, can become lose. When trying to remove the nuts on the inside of the chassis, they'll just spin around and  they won't undo. If this happens, you'll need a pair of mole-grips to carefully hold the studs from underneath the case while gently loosening the nuts with a box spanner on the inside of the case.

Mole grips can be a little aggressive so you might want to think about protecting the case with some thick tape. Put the tape around the lug of each stud and also put some tape on the tips of the jaws of the mole-grips. I found thick masking tape best for the case and lugs and cloth (or gaffer) tape is good on the mole-grips.

Taped mole grips to protect case
Doesn't look very pretty but helps protect your case.

When re-assembling, I would recommend replacing the nuts and soaking them in a lubricant like WD-40 prior to fitting.


The second point I should make is that with the exception of the Vecoven Flash module, all other upgrades mentioned here, require some considerable experience of soldering, desoldering, working with surface-mount devices and respecting electrical safety and electrostatic sensitivity. You should also be prepared to drill into existing PCBs and / or original chassis metal work.

!!! Remember, if you get it wrong, you might permanently damage your synth !!!

Today, my MKS-70 still looks pretty much as it did when my good friend Rob donated it to me, several months ago. Under the bonnet however, it’s quite a different beast. The sound is still lush and beautiful but...

  • As a result of installing Guy’s P0004 switched-mode power supply, not only has reliability and longevity been increased but this machine can be plugged straight into just about any mains supply on the planet.
  • The sounds can now benefit from pulse-width modulation thanks to the Vecoven PWM upgrade.
  • The Vecoven Super-JX flash module has increased the memory to a ridiculous amount; more patch changes and less SysEx transfers!
  • Firmware updates can now be performed over MIDI.
  • Guy's Super-JX OLED display looks quite simply, beautiful. To the experienced Super-JX user, it might be the only indication that something is err... different.
  • The Super-JX OLED will live much longer than the original VFD and FIP coil which can only give peace-of-mind.
Roland MKS-70 Fully Upgraded
Boot screen of fully upgraded Roland MKS-70.


Live Forever battery mod at Plasma Music

This is something I do which isn't unique to the Roland MKS-70 and which can be fitted into almost any synthesiser or effects processor. It's NOT literally a 'Live Forever' battery mod as nothing obviously lives forever. The chances are however, that it'll out live you!

The damage caused by battery leakage can be irreversible. It's not just a case of losing all those tones and patches that you err... forgot to back up. Battery leakage can seriously damage the PCB on which the battery is mounted; usually the CPU board in most machines.

I mount a high-capacity lithium battery off any PCB giving you the following three main benefits:

  1. Will last a lot longer than the standard CR2032 which is found in most synthesisers and effects processors.
  2. Mounted off-PCB so in the remote event that it does leak, sensitive electronics inside your equipment is protected.
  3. Positioned such that battery voltage can be easily checked by only removing the top of your machine.

If you missed it earlier, all my prices can be found here.


Anyone with a Super-JX will be aware of the Roland PG-800, a programmer / editor, specifically for the JX-10 and MKS-70. Today, PG-800s are hard to find, relatively expensive and quite honestly, you'd be lucky to find one in really good condition. I'm not talking cosmetically but electronically and it's worth bearing in mind, that parts are becoming ever scarcer.

Thankfully, a company called RetroAktiv makes a small collection of hardware programmer / editors for several popular vintage synthesisers... including our beloved Super-JX.

I don't have one of these myself but I've heard only good things about the RetroAktiv MPG-70. On top of that... damn, it looks good!

At 875 USD, the RetroAktiv MPG-70 costs a couple of hundred USD more than an original Roland PG-800. The thing is, even if you forget about the fact that this box is going to be considerably more reliable than thirty-something year old electronics, you're getting a lot more for your money and (I'm going to say it again) it just looks awesome.

If you're still not convinced, then RetroAktiv also makes a smaller Super-JX editor  called the MPG-8, which retails for just 349 USD.

One of the many features of both of these controllers, is full compatibility with the Vecoven PWM upgrade and firmwares.

For some time now, I've been using a plug-in called Ctrlr. It’s basically an open-source environment for Windows, OS X and Linux, which allows users to develop programmers and editors for just about anything. Many users share their ‘panels’ on the Ctrlr website and I was so surprised to find a panel specifically for the Vecoven V.4 firmware upgraded Roland Super-JX. This doesn't really fall into the category of Roland Super-JX upgrades as such but I think it still deserves a mention. Available for Windows and OS X, 32 or 64-bit and in plug-in or stand-alone format, you really need to check this out. Oh and it's free! 😀

Ctrlr Panel for Vecoven Super-JX

The RetroAktiv programmers will work with Super-JXs running standard (factory)  firmware although some sliders and knobs won't do anything as there's no PWM to modify, for example. The Ctrlr panel above will ONLY work with Vecoven version 4 firmware. While I've seen Ctrlr panels that'll work with Vecoven version 3 firmware, I haven't come across anything that'll work with bog standard Roland firmware.

It's been most reassuring to discover that I'm not alone, that there's a whole community out there that share my appreciation and even passion, for this underrated monster of a synthesiser. I'm so grateful to people like Guy, Fred and the RetroAktiv crew, who after more than thirty years from it's launch, have embraced the potential of the Roland Super-JX, developing upgrades that ensure this magnificent machine lives on.

I'd love to contribute what I can so please don't hesitate to contact me if you'd like more information on any of the Roland Super-JX upgrades mentioned here. I'd love to hear from fellow fans of this awesome synth. 😎

In the meantime, here's a few links that you might want to check out: - Sites like this, truley keep the legend alive! - An excellent reference site. - You just knew that there had to be a Facebook group, right? - ...or two!!!

UPDATE: 11th July 2020

Wow! Since I put up this post, things have got a little busy.

Super-JX mods at Plasma Music
Three MKS-70s and yes, well done! You've spotted the MKS-80 in the foreground.
Super-JX mods and upgrades at Plasma Music
This machine is having my Super-JX upgrade bundle fitted.

A relatively common problem on older equipment, is the failure of the LCD backlight (or EL-panel). Often accompanied with a very high-frequency whine emanating from the LCD area of the gear in question, it's time to consider LCD backlight replacement.

LCD Backlight Replacement at Plasma Music

Here's a Roland GC-8 editor / controller for the massive Roland R-880 reverb (circa 1988). Without the controller, the R-880 which really is an awesome machine, is kind of useless as there's little out there to program it via MIDI.

Roland GC-8 LCD Backilight Repalcement
Roland GC-8 with original LCD backlight (pink) and new LCD backlight.

Luckily and thanks to a company called backlight4you, LCD backlight replacement is now worth looking into to. A variety of EL-panels that are suitable for a whole bunch of older gear, is available at the company's website which is also full of other useful and related information. Their backlights are reasonably priced and arrive from Germany pretty quickly and in very stiff cardboard packaging.

After fitting the replacement EL-panel, I powered up the unit to check. Wow! It looks great and on this occasion I got lucky and that bloody annoying whine has gone!

Roland GC-8 with fully working LCD backlight

IMPORTANT: As a backlight ages, its electrical characteristics change, These changes put a strain on a small component called an inverter which converts dc within the unit to high-frequency ac which is required to drive the EL-panel. As this components deteriorates, it starts to whine. In many cases, replacing the backlight will fix that problem but... not always. : (

If after swapping out your backlight, your unit is still whining, then backlight4you may still be able to help. Take a closer look at their website and you'll find a section on inverters. Designed to run from common voltages and power many of the EL panels that are sold on the website, these replacements are very reasonably priced.

Replacement inverters might not be pin-for-pin compatible, especially with very old equipment but with a little ingenuity, you might be able squeeze a one in somewhere.

Due to the low cost of replacement inverters, I would personally recommend swapping out the inverter when fitting a new EL-panel.

Need help with a hard-to-read LCD? Drop me a line.

Switched-mode power supply for Roland MKS-70
Guy Wilkinson's P0004 switched-mode power supply for Roland Super-JX

Never thought I’d make a new friend over lock-down but I have recently struck up a relationship with Guy Wilkinson of

While working on a very broken Roland MKS-70 that I have in for repair, I came up with the idea to design a MKS-70 power supply replacement but figured that after all these years, perhaps someone has already thought of this. After a few minutes of searching on-line, I stumbled across The work that Guy has done, is truly amazing. His power supply design is quite simply, elegant and I’m so impressed with his methodical record keeping. As it turns out, Guy seems to be a bit of an expert on several vintage machines.

Anyway, having a Roland MKS-70 myself, one thing led to another and I’m currently in the process of building one of Guy’s P0004 switched-mode power supplies and installing his Super-JX OLED display module into my own MKS-70. It’s a bit difficult doing this during lock-down but I’ll keep you posted of progress.

Guy Wilkinson's Super-JX OLED upgrade module.
Guy Wilkinson's Super-JX OLED module. The background images show an actualSuper-JX OLED installed in a Roland MKS-70.

Guy sells the P0004 switched-mode power supply bare PCB and the pre-assembled Super-JX OLED  display directly but you'll need some competence to populate the former and fit either, into a JX-10 or MKS-70. If you're cool enough to admit that all of that sounds a bit too much for you, then please don't hesitate to contact me to discuss getting either (or both) fitted into your machine.

Click here for prices.

If you're fitting the switched-mode power supply module yourself and your MKS-70 or JX-10 has a 2-pin IEC mains input socket, then you must replace it with a 3-pin IEC mains input socket. The replacement switched-mode power supply MUST be connected to earth as must the chassis of your Super-JX.

I offer a comprehensive earth bonding kit comprising the following:

    • 1 x IEC 3-pin chassis socket.
    • 3 x pre-cut heat-shrink strips.
    • 1 x insulating boot for IEC socket.
    • 1 x M3 earth tag.

Switched-mode power supply module for Roland MKS-70 MUST be earthed

It is paramount that if fitted, a 2-pin IEC mains socket be replaced with a 3-pin IEC mains socket and that the chassis and the P0004 are connected to earth.UPDATE - 10th MAY 2020

Last night I installed the assembled switched-mode power supply into my own Roland MKS-70. I'd already tested it outside the machine but I was still nervous. Hey, the MKS-70 fired up straight-away. The power supply worked just fine and quite honestly, if you're having issues with the power supply in your Roland MKS-70 or JX-10, then getting one of these is a no-brainer!

Guy Wilkinson's switched-mode power supply installed into a Roland MKS-70
Look, no transformer! Coooool.

UPDATE - 12th MAY 2020

Took a while and was a bit tricky but the display got done and works absolutely brilliantly (pardon the pun). In fact it looks positively beautiful.

Super-JX OLED upgrade module installed in Roland MKS-70
Never knew what people meant when they referred to tech as "sexy". Now I do. I can't stop looking at it!!!!

The Super-JX OLED module 'learns' the system's firmware so before I switched on the unit to test, I thought I'd drop in the Vecoven Super-JX flash module. Pressed the power button and everything powered up just great.

UPDATE - 19th MAY 2020

Several days ago, I posted here that I'd keep you updated of progress on this project. I also suggested that I'd probably end up making a new post. Guess what? So, click here for more on Roland Super-JX Upgrades. 

Roland MKS-70 repair at Plasma Music

Recently, this gorgeous vintage Roland MKS-70 synth module came in for repair.

The MKS-70 is basically the rack version of the Roland JX-10 keyboard synthesiser, which itself is essentially two JX-8Ps. Also known as the Super-JX, the JX-10 and the MKS-70 are famous even today for their rich, analogue tone and pristine sound quality. At this point I need to make something clear; the Super-JX is not actually 100% analogue unlike for example, one of it's well known predecessors, the MKS-80. The oscillators are in-fact, digital. So when I refer to 'analogue' tone, I'm referring to just that, the tone.

Check out more details and some sounds here and here.

Anyway, the customer said that it wasn't powering up properly with just a flash briefly appearing on the display and then nothing. Well, let's see if we can get this ol' girl singing again..

Apart from being a giant classic, the MKS-70 like the MKS-80, has hinged circuit boards which means that it opens up quite nicely. Having said that, if you need to get at the 'CPU' board (the service notes refer to this as the Assigner board, for some reason), you really do need to disconnect and remove the lower analogue voice board.

Checking voltages before anything else, I realised very quickly that I had a major problem. The voltages on the power supply were all about 25% more than what they should be. Eek! Hope no serious damage has been done.

I'll keep you posted on this fix but please bear in mind that I'm respecting the COVID-19 lock-down so it may be a while before I'm back.

UPDATE - 2nd April 2020

The power supply is a really clever and well thought out design for the time but I don't think the Roland R & D team had any idea that their machines would still be making music over thirty years after their conception. There's a small voltage monitor chip on the power supply which, when it fails, sends the +/-15 V rails to like +/-22 V. Unfortunately the +5 V rail for the digital stuff has a dependency on the +15 V rail so if that freaks out, then so does the +5 V supply.

I decided to change all the major components on the PSU including transistors, capacitors, bridge rectifiers and of course that frigin' voltage controller IC. Okay, so now power is good.

UPDATE - 14th April 2020

Well the voice-boards turned out to be fine but the CPU or assigner-board, was seriously not happy. The code was trying to run but not getting anywhere. This was going to be a hard fix. My worst fears an' all that...

I'll get back as soon as I get somewhere... or not 🙁