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Super Nova switched-mode power supply for the Roland Juno-106
Super Nova, the world's first switched-mode power supply for the Roland Juno-106.

Following on from last summer’s Aurora project (read more about that here), I thought I’d have another look inside one of my favourite keyboard synths and see if I could do something similar. Well, it took me about a week to design the basics of what was very quickly to become the Super Nova switched-mode power supply for the Roland Juno-106.

Being a guitarist, my selection of keyboard synthesisers is quite modest but I consistently find it amusing that many musicians walking into my studio, inevitably make a bee-line for my humble Juno-106.

My Roland Juno-106
My favourite keyboard synthesiser; the Roland Juno-106.

I have always loved this machine! It’s just so easy to ‘draw’ a sound using the top-panel controls and it always delivers. Lush, phase coherent and warm with no mistaking that classic Roland chorus, the Juno-106 has played a big part in my own musical history.

Intended as a budget synthesiser, the Juno-106 was released in 1984, the same year as the MKS-80 and the JX-8P. It’s lack of velocity sensitivity and simple voice architecture didn’t seem to inhibit this monster-sounding machine’s popularity. Indeed, the Juno-106 is probably one of the best-selling synthesisers of all time.

My Roland Juno-106

Today many named artists still use this fab synth and variations like the Juno-106S and HS-60 (or Synth Plus 60) both with built-in speakers, still sit in many a lounge or music room. After more than three decades however, time is taking its toll. Many will be familiar with the failing 80017A VCA / VCO devices, for example. Fortunately, Analogue Renaissance offers a replacement, the AR80017A. My Juno-106 is doing alright at the moment so I haven’t had the opportunity to try these yet. Having said that, I’ve only heard good things about the AR chips and I salute Jeroen Allaert of Cask Strength Electronics for such excellent work. On top of that, they look really, really cool!

AR80017A by  Analogue Renaissance
In my humble opinion, one of the most significant developments for the Juno-106, the Analogue Renaissance AR80017A replacement VCA / VCO modules.

KiwiTechnics has always been a name you can trust when it comes to synth repairs and upgrades and after a couple of years in development, the guys recently launched a seriously powerful hardware / firmware combination for the Juno-106. Known as the Kiwi-106, this is a significant upgrade offering a huge array of fantastic and modern features that well, change everything! In fact one of the reasons Super Nova is red is to match the Kiwi-106 so I strongly suggest that you check out kiwitechnics.com to find out more!

All these people doing this great stuff for the Roland Juno-106 and I couldn’t find anyone making a replacement power supply. Perhaps it's because we all know that Roland power supplies are really quite robust and have stood the test of time.

Roland Juno-106 power supply
In my humble opinion, Roland has always made really good power supplies.

An interesting feature and unlike many synthesisers of that era, the transformer in the Juno-106 is multi-tapped meaning that by moving a wire from one post to another (and changing the fuse), you can use the synth on virtually any domestic voltage supply across the world. 

Juno-106 power transformer
Multi-tapped power transformer of the Roland Juno-106 makes international usage a little easier.

The thing is, power supplies do fail. If the transformer packs up for example or starts humming, then that’s it. That’s why I designed Super Nova. Not just a replacement power supply, Super Nova is a modern, switched-mode power supply for the Roland Juno-106, meaning that for a start, it generates considerably less heat than the original linear power supply. There’s NO mains hum either and since Super Nova's filters are based on my good friend, Guy Wilkinson's design, Super Nova is also super quiet. And of course, being a switched-mode design, you can still plug your Juno-106 into any electricity supply around the world but this time... without having to open it up and change the transformer tap!

Super Nova installed and powered up
Super Nova installed, powered up and showing status LEDs.

Individually coloured LEDs for each supply including the 5V reference voltage, means that you can very quickly check line status with a glance. If you really want to know what's going on, conveniently located test points make measurements a breeze.

Super Nova status LEDs and test points
Super Nova also has conveniently placed test points.

The 5V reference voltage is set when each Super Nova is made, using regularly calibrated test equipment. A multi-turn pre-set however, allows for fine adjustment which may be necessary after several years, due to component value drift.

Super Nova allows for fine adjustment of 5V reference
Although set up when built, Super Nova allows for fine adjustment of the 5V reference. Also pictured is Q2 which is a power-on-reset device to ensure that the processor in the Juno-106's doesn't start running code before everything is powered up.

One of my most popular upgrades to many machines I receive from customers, is my Live Forever battery mod’ and so like Aurora, Super Nova includes a provision to replace the memory back-up battery in the Juno-106 and take it off the CPU board. This has several advantages:

  • A much larger back-up battery can be installed meaning that you probably won’t have to change it in your lifetime!
  • In the unlikely event that the battery leaks, your precious CPU board is safe and won’t be damaged by battery fluids.
  • Battery voltage can be easily checked without fuffing around with the CPU board.
  • Just in case you do have to change the battery, it’s so much easier and doesn't require any soldering.
Super Nova has on-board back-up battery for Juno-106 memory back-up
Super Nova has on-board back-up battery for Juno-106 memory back-up.

The battery connects directly to the original battery points on the CPU board so all components associated with the back-up battery continue to function as as normal.

Like several synthesisers of its day, the Roland Juno-106 is built on a plywood base. Heavy items like the keyboard assembly and power transformer, are attached to the base using machine-type screws that secure into corresponding steel lugs which are sunk into the plywood. The much lighter PCBs however, simply use wood screws to secure them (via spacers) to the wooden base. When you consider that the plywood base in less than 10mm thick, that sounds a little risky. On the other hand, there's no history of 'stuff' coming lose!

I wanted Super Nova to be super secure so although the PCB could have actually been smaller, I chose to extend it, thereby taking advantage of the otherwise redundant M4 lugs that were previously used to hold down the transformer. Mounted on an aluminium plate, both PCB and plate are very securely anchored to the base of the Juno-106. The plate is further held in place with four wood screws.

Super Nova is anchored to redundant transformer mounting lugs
Much more secure than just screwing to the plywood base, Super Nova is anchored to the redundant transformer mounting lugs.

Super Nova fits perfectly into the Juno-106 and is relatively easy to install by anyone with some technical competence.

Super Nova wiring
Super Nova is even easy to wire-up.

It's very efficient, can be plugged into just about any power outlet in the world and has on-board Live-Forever battery mod.

Super Nova fits perfectly into the Juno-106
A perfect fit and there's no messing about!

UPDATE - 6th January 2021

Super Nova has now been fully tested and me and my Juno-106 are lovin' it! I've completed detailed and fully illustrated, step-by-step installation instructions so, if you have a Roland Juno-106 with a bad power supply and are considering a replacement or if you have any questions, please just contact me.

Or you could just...

My favourite synth, the Roland Juno-106.


Plasma Music Limited -

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. 

Super Nova was designed by me and every Super Nova is hand-built and tested by me, here in Hemel Hempstead, Hertfordshire. The aluminium mounting plate is made by Lenton Engineering which is based just up the road in Watford and the printed circuit boards are manufactured by Minnitron Limited in Ramsgate, Kent.

Plasma Music uses local manufacturers

At the heart of Super Nova are four high-performance Vigortronix AC / DC converters which are made in Witney, Oxfordshire.

Super Nova uses Vigortronix AC DC converters made in the UK
Super Nova uses Vigortronix AC DC converters made in the UK.

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

Aurora - switched-mode power supply for the Roland MKS-80

Aurora - the world's first replacement switched-mode power supply for the Roland MKS-80.The Roland MKS-80 is an amazing piece of equipment and a lovely sounding machine. As one of the last all-analogue-voiced synthesisers, I am hopeful that Aurora, a replacement power supply for the Roland MKS-80 will keep all of those gorgeous modules still left on the planet, working just a little longer.

Anyone who has a Roland MKS-80 with a power transformer that’s not native to their region, now has the option to upgrade the power supply in their machine and plug it straight into their mains supply, without the need of going through an external transformer.

Anyone with a Roland MKS-80 that has a bad power supply or broken transformer, can now bring a new lease of life to their machine. Also bear in mind that the old FR2 PCBs are now very brittle and prone to dry joints and even cracking.

At the time of writing, some Roland MKS-80s have been operating for thirty-six years! While designed extremely well, the power supplies are stressed systems (as in any machine) and the last thing any MKS-80 owner wants is for the power supply in their machine to go south. IC1 on the original PSU for example, is a M5218L. It's a crucial part of the +5 V supply and the 10 V reference circuit. If this packs up, the  +5 V rail could rise to values that could seriously damage your MKS-80 and even make it unrepairable. As time goes on, the likelihood of this happening, only increases. The +/-15 V supplies which drive the voice boards, are a little more robustly designed.

Aurora switched-mode replacement power supply for the Roland MKS-80

Electronics in general doesn’t like heat. Aurora runs much cooler than the equivalent linear power supply.

Over time, your MKS-80 may develop transformer born hum. This can't be 'filtered' out and you're kinda stuck unless you can acquire a replacement transformer. Hey, you're in luck 'cos Aurora doesn't produce any hum!

Roland MKS-80 transformer
Here's the transformer in a Roland MKS-80. After a couple of decades, they can develop hum.


Originally, Aurora was going to copy the footprint of the original MKS-80 power supply. A single L-shaped board however, would have meant a lot of wastage and potentially necessitate the removal of the front panel to replace the original mains wiring which would have been too short to reach the single PCB.

The solution was to split Aurora into two PCBs; Board A being the main part of the power supply and Board B taking care of mains protection and filtering.

Aurora Board B on mounting bracket
Aurora Board B on mounting bracket. This occupies the space previously taken by the transformer.

I made use of the reinforcing plate that's underneath the original transformer. The size of board B is the same size as this plate. I simply added four M3 mounting holes. This all provides for a very tidy and cost-effective solution that requires minimal reworking of existing wires, etc.

Aurora's 10 V reference source started out as a precision circuit using 0.1% tolerance components and a high-grade op-amp. The results were impressive but later, I changed the design and incorporated a multi-turn trimmer so as to allow for adjustment of the reference which may result from component drift over time.

Provision for fine adjustment of 10 V reference on Aurora Replacement Power Supply for the Roland MKS-80
Adjustment of Aurora's 10 V reference, allows for compensation of component drift over time.

Each supply has it's own status LED. I thought this would be a nice addition and in keeping with the original design although unlike the original, Aurora has a different coloured LED for each supply, including the 10 V reference.

Also note the test points allowing for easy checking of all voltages.

Individual power rail status indicators on Aurora switched-mode power supply for the Roland MKS-80
Aurora has individual power rail status indicators (LEDs) and conveniently placed test points.

So I was going to teach myself Arabic or Mandarin during lock-down 2020 but instead, I kind of decided to design this. It just seemed like a really cool thing to do! 😀 😎

You can read about the development of Aurora Replacement Power Supply for the Roland MKS-80 here.


INSTALLING AURORA

Aurora Tidy Cabling
Keep cabling neat and tidy.

Installing the Aurora boards requires a certain degree of knowledge, experience and skill. I therefore insist that the installation be performed by a suitably qualified technician. Aurora is a power supply that converts mains voltage to several DC voltages that your machine requires. Safety is paramount and although fully tested prior to shipping, I strongly recommend that you test Aurora outside of your machine prior to installation. Since there is mains voltage on both boards, care should be taken that the boards are lifted clear of any work surface during such testing, using for example, PCB stand-offs (spacers).

Removing the original power supply including the transformer also requires a certain degree of knowledge, experience and skill. Remember that these machines are over thirty years to over thirty-five years old.

The voltage distribution headers for example, are soldered to the board. The pins on the headers are not conventional straight pins. They're arrowheads and have a tight fit. Once you're confident that you've removed all of the solder, gently prize  them off the board (GENTLY). I suggest that you wiggle the connector from the component side while observing the underneath so as to ensure that all pins are indeed free.

Header on MKS-80 power supply showing arrowhead pins
+15 V header on MKS-80 power supply showing hollow 'arrowhead' pins.

Don't simply cut the wires to the transformer and the terminals on the original power supply board. Instead, try to unwrap so as to preserve the original length of wire. You may trim some of these later but you don't want to be left short!

Require tools and equipment are as follows:

    • Temperature controlled soldering station (e.g. Weller WE1010)
    • Temperature controlled de-soldering station (e.g. Duratool D00672)
    • Small wire cutters
    • Small pointed pliers
    • Adjustable cable strippers
  • Set of cross-head screwdrivers
  • Small flat-head screwdriver
  • Set of box-spanners (metric)
  • Tweezers
  • Digital multi-meter (DMM)

PLEASE don't use a plumber's or electrician's soldering iron and please don't use a manual solder pump. You'll just wreck things. In fact, if you're thinking of using that kind of equipment, you shouldn't be operating on your MKS-80, let alone installing Aurora!

Aurora showing close-up of SMDs.
Finally Aurora is up and running... beautifully.

A few hints on workflow:

  • Do NOT rush it! Take your time.
  • Check and double check your work after each stage.
  • Do not rely on the status LEDs as indicators of required voltages. Use the test points to measure the voltages with a DMM.
  • When removing screws and nuts from your MKS-80, use a 'gently, gently' approach. You really don't want studs to loosen or threading to shear.
  • Do NOT over-tighten screws and nuts. You're dropping a replacement power supply into a vintage synth module and not building a spaceship that's destined for the outer planets!
  • The 10 V reference has been set by me using a regularly calibrated DMM. Please do not mess with it!!!!!
  • Note the orientation of the headers before you remove them. It's actually not too important other than to keep things tidy except... for P7. Unlike the other headers which each carry a single supply, P7 carries the 9 V supply and a digital ground, to the programmer (MPG-80) port via the output board. It's VERY important that this connector's original orientation is maintained.
  • Your MKS-80 MUST BE EARTHED.  If you have a 2-pin IEC mains socket, you must replace it with a 3-pin IEC C14 socket. The earth pin should be connected to Aurora Board A and Aurora board A should then be connected to the chassis. There's a hole in the lower case in between the mains socket and the side of the MKS-80 chassis which will take a M4 screw. DO IT!!!! Aurora board B must also be connected to this point.

Here's a wiring diagram showing how the two Aurora boards are connected to each other, the mains input, the switch and earth / chassis. Also illustrated is the use of existing (original) wiring as well as some new wiring.

Aurora Wiring
It's really quite straight-forward. You just need to take your time and remember that you're working on a vintage synth module.

Aurora Star Earth Bonding
If your MKS-80 has a 2-pin IEC mains input socket, then you MUST replace it with a 3-pin (C14) IEC socket and connect earths as shown. Also note the insulation boot over the C14 connector.

 


UPDATE - 7th October 2020

Since August's flood, I've had to move ops back home, temporarily. It's very cramped, things are taking longer (it took me two days to find my oscilloscope) but Julie my wife, is amazingly patient and understanding and a big support during this challenging time.

I currently have three MKS-80s in for Aurora and OLED module upgrades. Two of them have already been done but the fourth (a Rev 4 at the back), has a dead voice which I need to fix before I do anything else.

Looks like people are finding out about Aurora
MKS-80 heaven; two Rev 5s and a Rev 4 (ex Trevor Horn), in for Aurora and OLED upgrades.


UPDATE - 2nd December 2020

So the past few months has seen more than a few Aurora sales and installations. Many customers whose units I've had in, have asked if I could also install my Live Forever memory back-up battery mod and it got me thinking.

Aurora has two boards. Board B comprises mains protection and filtering so, not a lot. With a little nudging, I was able to fit a CR123a battery holder on to the PCB and so Aurora Bx Board was born! Read more about it here.

New Aurora Bx board with large capacity back-up battery
Aurora Board Bx with on-board back-up battery mod, is now available.


UPDATE - 24th December 2020

Aurora installation instructions are now available in German.

Die Installationsanleitung für Aurora ist jetzt in deutscher Sprache verfügbar.


UPDATE - 24th April 2021

Aurora is now offered with the optional V06 data cartridge re-enforcement bracket. Such a cool solution to a problem that many Roland MKS-80 owners will be familiar with, the V06 basically strengthens an undamaged cartridge slot and reinforces a broken one by putting 2mm of solid steel behind it!

V06 Bracket for Roland MKS-80 Data Cartridge Slot
V06 bracket for Roland MKS-80 broken data cartridge slot assembly.

Existing Aurora customers take note; once your Roland MKS-80 is open, V06 can be installed in a few minutes, with just a M3 (5.5mm) nut-runner.

Read more about the V06 here.


Plasma Music Limited -

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.

Environmental considerations of delivering Aurora
Remember the 'Colours of Benetton' adverts from the eighties? A little shock, horror to make the point. So rest assured that Aurora boards are manufactured here in the UK by Minnitron Limited.

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.

Please don't hesitate to contact me if you have any questions regarding the Aurora Replacement Power Supply for the Roland MKS-80 or, if you want to buy Aurora or book in your MKS-80 to have it fitted, please check out my store.

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

SO WHAT DOES THIS MEAN ANYWAY?

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 not actually going to make any difference!

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, as seen by the mixer those signals are going into. If the amplitude of both sets of outputs is the same, you will in fact get absolutely nothing as the two pairs of outputs will of course cancel out each other.

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