As part of my journey to replace old and potential problematic parts inside Cora with new “like for like” parts if available, my travels next steered my focus towards the many and varied ribbon cables inside a Jupiter 8. These big grey tentacles of various size and width stretch all over the place inside a Jupiter 8, taking digital control signals to and from the main CPU board to voice boards, slider boards, etc. They are mainly there to assist in the purpose of saving patches to memory. An old analog synth that doesn’t need to save patches, like a Minimoog, doesn’t need digital stuff ie no ribbon cables inside. The digital signals work together in a parallel fashion, where one wire in the ribbon is dedicated to a certain function or value and all of the wires work together “in parallel” at the same time. This is a very Ole-Skool method of digital control, confined to digital systems of the 80s and 90s. It wasn’t so long ago that hard drives in the common garden variety PC used this parallel form of communication with the “grey ribbon”…
Nowadays, digital signals are sent around in a “serial” fashion (eg SATA). In theory, parallel communication and the grey ribbon cable should be faster (=better?) than serial. And it IS a faster option when your signal processing “decoding” chips are slow and big and expensive, as they were in the 80s and 90s. Parallel means you don’t need so many of the decoding chips, as the signal is already split up and ready to use. But once they made signal processing chips fast and small (surface mounted) and cheap, the world of digital moved to serial, where every communication value of every different signal all goes down one (or 2) wires in a row, one after the other in a “serial” fashion and fast little surface mounted decoding chips are scattered around the synth and pull the data they want from the “main data line” that is only useful for that part of the circuit. This diagram sums it up nicely:
As a side note, an early example of serial digital communication is MIDI. It was easy for Dave Smith to choose serial for his MIDI protocol because there was not that much data that needed to fly down the midi lead. Just a few data bits for what note was pressed. But anyone who has run all 16 midi channels with notes down a single midi lead along with some pitch or mod wheel movements will know that the timing of notes playing quickly gets sloppy … The 1981 speed spec of 31.25k can’t keep up. In contrast, Roland’s early attempt at digital communication was DCB, and Roland went for Parallel. That’s why DCB leads are thick and full of wires. And probably why it didn’t take off, even tho it probably would have had better timing under load, the leads needed to be short, they were thick and expensive and the plugs bulky.
My point is that for all these reasons, Cora, born in 1982, has the old parallel communication inside her… ie the grey ribbon cables, whereas today’s modern analog synths look neat inside and don’t need the ribbon cables all over the place. Jupiter 8s have yards of the stuff.
It’s important to note that these ribbon cables do not carry audio signals. It’s critical in synth design to try and separate digital signals going thru ribbon cables from audio signals so as to avoid introducing digital “noise” into audio… that annoying clicking and purring that you can sometimes can hear in a cheap PC soundcard’s output for instance. The Roland Jupiter 8 voice boards are brilliantly designed and a beautiful work of art for many reasons, one is because of the way they keep the ribbon cable signals away from the audio output signal wire on the board.
Even the direction that the leads run when connected is important .. one makes its exit bottom right whilst the other goes up and away. This is no accident. Far away from each other as ideally possible. Nice.
But when it comes to grey ribbon data cables .. well there’s certain problems with them. Firstly and foremost, they’re big and bulky and stop the effective flow of air (= heat) around inside a case. This was a big reason why they were banished from inside PCs.. they blocked up airflow and pushed hot air in different directions for every PC… it could never be reliably predicted how the air would (or wouldn’t) flow around inside and one random twist of a big ribbon cable could change everything inside airflow-wise. Looking inside a Jupiter 8 you can see how a big pancake layer of ribbon cables sandwiched in the middle does the boards no favours when it comes to breathing. Just imagine a chip stuck underneath that big grey cable in the pic above .. it’s going to run hotter than if it lived out in the open on the left side somewhere because it is trapped and can’t breathe ..and that equates to shorter lifespan in the long run.
Another biggie is ease of damage.. one pinch of a ribbon cable.. and those tiny strands can be internally severed. And it may not be that easy to see visually.
Then there’s ageing… the plastic coating becomes brittle, and the wire strands rust inside and become stiffer/less able to bend, and the impedance of the lead changes. ie 1m Long cable starts to behave like a 10m Long cable. Therefore occasionally a signal bit doesn’t reach its destination .. and chips lock up in fright. Your synth crashes randomly sometimes and you dont know why.
Then there’s reliability of those black plastic connections on the ends. The whole plug is a fairly primitive one.. Up to 50 metal pins all line up to get shoved into 50 holes all at once and need to rub against 50 little terminals inside. It’s not a plug-system that enjoys frequent cycles before going faulty. And of course there’s the issue of having somewhere to grab onto properly with your fingers when pulling and tugging at a ribbon cable plug to get it released … most people just grab a hold of the wire rather than the actual black plug and just yank at it. Pins bend.. wire threads stress and snap. Sometimes just enough to make the connection unreliable. After all they can be stubborn suckers at times to get unplugged and released. Plus the pins.. they corrode. I’ve lost count the number of times I’ve fixed a synth that is behaving “glitchy” by just cycling / reseating its ribbon plugs… effectively scraping away some of that oxidization from the pins and creating a solid contact again just from the process of unplugging and re-plugging the cable back in. I’ve read several forum posts where people complain that their Jupiter 8 is fine until it’s moved or just repositioned slightly .. then it behaves badly. Often.. a slight twist of the case, and bad ribbon cable connections can raise their ugly head. Open it up, unplug them and plug them back in. It’s that simple…A lot of the time, Problem solved. Then you’re told that it was the “Johnson Rod that was fusing with the Torroidal chip causing Mainline fluctuations” ….cost=$300 for (in reality) a ribbon plug reseat. Happens far too often. Here is a similar situation demonstrated well in Seinfeld:
In my case, the ribbon cables inside Cora were..well …”stuffed” is the word. Some had changed color in areas to a burnt golden brown from years of laying in the wrong place across the power supply and cooking from excessive heat…
They are meant to be a bright grey color but Cora’s had reduced to a blotchy yellow- brown. Some had broken down and stiffened in places and the one that runs to the top panel had been twisted and jammed carelessly in the wrong place when the top was closed by Cora’s previous disrespectful owner, causing it to look buckled and damaged. They looked like a mess, covered in dirt and grime …far from the nice and neat examples I had seen online. They were hanging in there and seemed to be still working, but only just.
All of this equated to a big requirement for.. new ribbon cables to be made.
I started with buying some standard light-grey 50 core stuff from my local electronics store. It is easy to create smaller width runs by simply counting the cores required and pulling away the extra wires but always leaving the wire #1 (usually pink or red striped wire running along one edge) that assists with orientation.
I quickly established however, that not all ribbon cable is the same. The Roland wire felt thick, substantial, quality. The stuff I purchased from the local electronic parts shop felt thin, flimsy, cheap. I checked the two other main electronic supplier chains in my city and they all had the same kind of cheap flimsy stuff. This was not going to be as easy a job as I had first imagined. Roland Japan used quality ribbon cable for a reason, and if I was going to replace it, then it would need to be with the same or better quality stuff as well. My suspicion was that voltage would drop more in the cheap stuff between points, ie it’s impedance would be greater, acting like more of a giant resistor wire in its travels which would throw out all sorts of problems with correct voltage signals arriving between points that would affect accurate sound recall, timing, reliability etc.
I conducted some exhaustive searches online over several weeks. Ribbon cables come from different brands, and have AWG (Wire Gauge) counts, voltage and impedance ratings etc. I learnt that good brands were 3M, TE, Amphenol and Harting ….I found them easily enough on sites like RS Components and Mouser, but in every single case, the good quality stuff was only by the full reel! And cost up to $300!! I could not find anywhere online that would sell me quality branded ribbon cable by the metre. (You need to buy 5m worth to be able to comfortably replace the lot inside a Jupiter 8).
I would need to look further and deeper locally. I tried several small independent shops, and at one of the last little spare PC parts places I tried, I hit pay-dirt. It was a hot day and there was no air conditioning in the shop. This miserable looking staff member eventually dragged himself out from the back to the counter looking deshevelled and beaten down, but holding the most beautiful roll of 3M 60 thread cable. I knew that good quality 50 core comes in at around $10 per meter so I was expecting to pay a little more p/m..
Guy:”So .. how much do you want?”
Me:”5 meters would do the trick…how much you got there on that roll?”
Guy:”I dunno..I can’t really be bothered measuring it out in this heat how does $20 bucks cash for the rest of this roll sound?”
Nothing like a disillusioned employee to help you out with a bargain!
I was estatic with joy. Score! There was over 7m on the reel! Here’s a pic below with both the standard 50 core ribbon cable on the left and the high quality 60 core branded cable on the right…it’s not easy to tell just from a picture but once you hold it in your hands, feel the weight and see the thickness of the strands coming out the end it’s a significant difference and you understand instantly :
Now a closeup of the cores to try and demonstrate better the difference …the top cable is the cheap stuff. Look at the size of the small silver dots (strands) compared with the larger/more significant size of the silver strands poking out the end of the high quality cable underneath it …
… Time to start cutting it up and stripping it into replicas of the originals. Cora has some 50 pin sections, 40 pin, 26 pin, 20 pin and 10 pin. This is why 50 (or more) core lead is the ideal choice as you can easily make up all of the lower generation sizes from it. You will need to buy lots of new black ribbon cable plugs of these sizes. They are not re-useable so all new ones are the order of the day, plus they are cheap and readily available everywhere and the old plugs are very likely oxidized inside and part of the problem. I highly recommend you treat your original cables very gently during this whole process, bend them as little as possible, there’s every chance the ones you are remaking could have some fault in your plug attachment process (which can be tricky affair), and you might need to revert to your original leads to track down a problem.
There is a ribbon cable plug attachment tool that you can purchase. They cost around $30. They look like this :
If you are going to be making lots of ribbon cables up in the future then they are a worthy investment but for the few attachments we need to do for this job it’s just as effective to use a bench vice that had its claws covered in some gaffa tape to protect the plugs from damage in the attachment process. This is a completely legitimate method that many use for just a couple of plug attachments like we plan on doing:
You get only one shot at attaching a ribbon cable plug. The top of the plug teeth line up perfectly with the cable core and pierce thru the outer cable cover.
The top clip helps with the process and the side clips click into place as the plug closes. Get the alignment wrong, or attach the plug on crooked (or the wrong way around…easy to do!) and you have to throw out the plug and the ribbon need to be trimmed and you need to start again. You simply can’t undo the clips without them breaking. Trust me when I tell you that you will get a few wrong. Buy extra spare plugs or you will be making several trips to the electronics store. Practice on the smaller plugs first, because they’re cheaper to buy more of when you get it wrong.
The plugs I used have the directional lug on them (the most common you will be able to buy) that is used for male sockets that accommodate it. The early days of these sockets and plugs didn’t have this lug and Cora’s sockets are of this early type, so the lug needs to be shaved off so it can fit into Cora’s sockets. Here’s a pic … I just used a box cutter knife to take off the lug BEFORE attaching:
Make sure the cuts you make to the ribbon cable are PERFECTLY straight across. Otherwise you’ll attach the plug on an angle too, and it will cause stress on the cable if the runs are not sitting straight in your Jupiter 8. Or if you adjust the plug to be straight and the cable sticks out the end of the plug crooked it’s hard to impossible to neatly trim it later once the plug is attached. Just get it right from the start. Use a guillotine or mark up where you are going to cut with a black pen and use scissors to cut.
Then into the vice with the new plug sitting gently in place and the vice cranked hard and I leave it closed for 15-20 seconds or so before backing the pressure off …
Nice and clean plug attached!:
There is a small degree of leeway when it comes to exact cable lengths as there’s a bit of room for error inside a Jupiter 8. One of the things I noticed was that Roland never made the 50 pin cable that connects across the main voice boards together exactly the right length, and there’s some excess. It’s not quite as easy for this big cable to find room for the slack, it’s a tight, short distance and the cable is stiff and wide. Jupiter 8s have this cable inside “dipping” down between the voice boards to try and use up this excess cable. Here’s what I mean …
Now that we are remaking these cables, here was a perfect opportunity to get the ribbon cable length “just right” and fix this sloppy measurement. I could not think of any justified reason why Roland would have done this on purpose, it sure wasn’t some primitive kind of cushioning as the boards are all screwed down and rigid in their position. My guess is that they designed the synth and started building it and then the guy walked into the factory “your 10,000 ribbon cables have arrived” and then they grab one from the pile to attach and realized “oh shit… they’re a bit long… someone’s screwed up, we gotta use them we got 10,000 ok let’s just tuck it around the place…”. So when making this cable up yourself, pay attention to the 50 core voice board socket plugs and measure them out on the synth to make the plug positions fit so the cable lays in a neat and relaxed manner…there needs to be some slack in case there is some movement in the chassis so they don’t pull and stress the boards but not so much slack that the cable starts to buckle up. It will look much neater and won’t require you to stress the ribbon cable from the tucking and bending job that Roland needed to do. Here is an idea of the two cables next to each other and a ruler…
So now with the middle plug lined up on the old and new cable (on the right)… here is the difference in the short end …you can see the plugs on the left are not aligned… and if the kink in the old original lead was completely removed it would look even more significant (I didn’t want to bend out the old lead completely in case it fell apart)
And here is the longer run of the lead .. again with the centre plug (on the left) aligned:
You should align these yourself with your own synth as you are making them. The lower voice boards’ 50 core cable can be a little tighter as they are locked down in place, whereas the top voice boards need to be able to swing up on their hinges to gain access. Make sure there is enough slack particularly in the top ribbon cable for the voice boards to swing right up together with the cables still connected… you don’t want to be unplugging and plugging the ribbon cables every time you swing the boards.
Another problem I discovered was that for a particular reason, Roland decided to skip installing a plug at the end of one ribbon cable, and instead hard-wire the cable directly into the pcb. The pcb in question is the switches and slider panel controller board that sits strapped to the underside of the main top panel and cable hangs down inside and runs a long distance to the cpu board. This makes it a monumental pain in the ass to replace this cable due to it being hard-wired…
It was however not a cost-cutting measure as this would outwardly seem. There was a good reason why Roland’s forward-thinking engineers specified it. This ribbon cable attachment sits upside down when Cora is closed. Roland wanted to make their flagship synth as road-proof as possible, they knew that Gravity Works and would be pulling downwards on this cable inside constantly, and that there was a chance that this plug could be encouraged to fall out of the socket if the synth was knocked around in a road case and the G-forces on it multiplied. So they removed the socket so the cable simply could not fall out and there was one less thing that could go wrong. It’s the same reason why they glued down the big power supply caps on top of them being soldered, in case they flew loose due to the stresses of pop music touring. Smart. Roland were thinking ahead and a care-factor was present (unlike most design and manufacture these days). It’s so true that they really don’t make synths like the way they used to. But this did not make it easy with the job of replacement.
I had to remove the ribbon cable but decided instead of hard-soldering the new ribbon cable back in, I would install a socket in its place. As a workaround I would put a blob of hot glue across the plug to secure it. Cora would never be going “on tour” that’s for sure so there was also not the concern of the plug falling out whilst she was in her roadcase that was being used as a mattress by a lighting roadie who was getting paid by a groupie the backstage pass he had promised her. First job was to desolder the old hard wired connection :
And then to solder in a 40 pin socket to be able to easily connect a new ribbon cable and easily disconnect a faulty one or work on the board easier in the future without the giant umbilical cord of a cable being dragged along.
Finally …some of the newly remade cables next to the old originals… ready to be swapped out and installed: