SOUND ON SOUND

[Hugh Robjohns]

It's almost certainly a standard aluminium extrusion, so you should be able find something the same or very similar from the usual suppliers... such as:

https://www.digikey.co.uk/en/product-highlight/a/advanced-thermal-solutions/extrusion-profile-heat-sinks?utm_adgroup=General&mkwid=sTovGldjA&pcrid=267270543726&pkw=&pmt=b&pdv=c&productid=&slid=&gclid=EAIaIQobChMIruDY3K2b4wIVSPhRCh1-qQPOEAAYASAAEgIFwPD_BwE

[DarrenGlen]

Hi Hugh! Thanks for your post!

Nada I’m afraid. Coras heatsink is very unique. It needs to have the same amount of fins, the same height and spacing for the amount of heat it’s dissipating. As well as to look right. All the similar sized ones I’ve ever found have the fins running the wrong way... vertically instead of horizontally.

Roland made the heatsink run this way so keyboard players would not slice their fingers apart when they reached around the back of the synth to pick it up.

I do have a 3D file of the heatsink. But so far to get one laser cut to spec is running at $600 US plus. Which I find rediculous. Maybe I should start up a Gofundme campaign to get the heatsink cut hehe (of course I would not do that)

[Eddy Deegan]

I've just re-read the entire saga from the first post up to the present. Although I've been following periodically, it's quite amazing to read in one go. I learned a lot from the documentation you've created. The high level of detail about slider construction, pots, ribbon cables, ordering spares, LEDs, switchwork, metalwork (the list goes on) are extremely interesting and likely to be of use in future.

This is the most thorough and ambitious synth rebuild I've ever seen. I reckon when it's done you could write a book about it... I'd certainly buy one!

One thing I was curious about. You went to great lengths to replace the ribbon cable and you mentioned the fragility of the original cable looms yet there was no mention of replacing any of those. Was that because you are happy they are going to be reliable enough for the forseeable future, because of the work involved or some other reason?

The whole thing is epic. I look forward to the next installment! :thumbup:

[DarrenGlen]

One thing I was curious about. You went to great lengths to replace the ribbon cable and you mentioned the fragility of the original cable looms yet there was no mention of replacing any of those. Was that because you are happy they are going to be reliable enough for the forseeable future, because of the work involved or some other reason?

The whole thing is epic. I look forward to the next installment! :thumbup:

Heya Eddy! Thanks for the awsome comments I appreciate it! And they give me a boost to keep doing the blog. I kinda think the same now about the information amassing, hopefully it stays up forever as a kinda reference point for anyone else needing to tackle the job and it saves them some money by helping them to do at least some of it themselves (“hell if this guy can do it ... I can do it !!) and maybe saves a few mis-haps.

Re- looms... excellent question. I want to re-do them. But they are in good condition (not burnt or buckled like the ribbon cable) and ... most crucially, the white PLUGS on the end are from Unobtanium. I would have to replace all the board sockets and use more modern ones that are available.

There’s no doubt the looms are stiff and the wire inside aging. If I were to bend one of them 90degrees I feel like it would “crack” rather than bend. I’d say the roaring heat inside from that PS has certainly cooked the looms to a decent degree.

I think I’d like to get her up and running first ... it’s been soo long without being able to experience the Jupiter velvety warmth. I just wanna play her!! And then once I know she’s 100% working ok i could make that a post-project.

Cheers !

[Eddy Deegan]

Thanks for the insight Darren, that makes complete sense.

A good mate of mine has a decent 3d printer. If/when you decide you want/need to work on the looms, retain the original Roland sockets and reproduce those plugs and if you can't find a more local source (I'm on the other side of the marble in the UK) then if you put together enough information for us to reproduce them I would be more than happy to cover the costs of doing that for you, including repeated shipping of prototypes and iterating to whatever polymer produces the best results.

I am not sure off the top of my head what file format his software uses, I suspect STL but that can be established at the time. We'd just need a precise enough model to work from.

It's a little thing I know and I'm sure you can find someone more local but the offer remains open so in the event you need to, feel free to ping me here via PM on the SOS forum at a later date. You've gone to so many lengths and put so much into the project that if I can assist in some small way I would be delighted to do so. No hurry, I've been in the SOS forums for 15+ years on and off and have no intention of disappearing anytime soon.

The blog is great, don't stop! Not only for my sake but I know there are a number of folks over here following. All the best and please do make a video of you playing Cora when she's shipshape. There is little question in my mind that through your efforts you now have the best Jupiter 8 on the planet. I had a chance to buy one for stupidly little money over 30 years ago as a youngster and didn't because I didn't realise how amazing they are. I'll always regret that.

Your journey, the docs, the love for the project and so forth is inspiring - cherish her! :thumbup:

[Folderol]

Truly an epic! I'm continuously amazed at your total dedication and attention to detail, and that panel looks absolutely stunning :bouncy:

With the looms, if plugs and sockets are OK, and the plastic isn't obviously cracked (or significantly discoloured) , I would be inclined to just very carefully clean them then leave well alone. If there is any concern about them cracking when being moved, a fairly prolonged, but gentle application of heat will usually make them more flexible - at least while they stay warm - it does of course depend on the exact formulation of plastic that was used.

[Martin Walker]

With the looms, if plugs and sockets are OK, and the plastic isn't obviously cracked (or significantly discoloured) , I would be inclined to just very carefully clean them then leave well alone.

I totally agree, having once made the mistake just before selling a small mixing desk of mine to spray both halves of its external PSU connector with Caig DeOxit.

This made the connector feel a lot 'smoother' and cleaner, but unfortunately more prone to dropping out if you as much as sneezed in its general direction :headbang:


Martin

[DarrenGlen]

I would be inclined to just very carefully clean them then leave well alone.

Well yes. There are so many areas where things could go wrong at the moment that I just wanted to rule out the looms as a possible fault culprit at least until Cora is up and running.

I will be replacing a lot of the heavy wiring around the power supply tho. Especially those wires that bend and stretch every time the top panel is opened ... my guess is that they’ve been twisted hundreds of times

[Hugh Robjohns]

Multi-strand wires don't usually fail, regardless of how often they are moved.

Solder joints can fail, obviously, and -- depending on the composition -- some plastic insulations can harden and potentially crack with heat and/or age... but it's not that common, even in 40/50 year old equipment.

So I wouldn't rush to replace wiring just because. I'd examine the insulation and see if there is any genuine need, because disturbing old solder joint on PCBs is likely to cause more problems than leaving well alone!

H

[DarrenGlen]

Hi all new post is up... a list of every single electrolytic capacitor in a Jupiter 8.
Many differences to the service notes. An important new resource !

https://jup8restoration.wordpress.com/2 ... jupiter-8/

[Folderol]

Hi all new post is up... a list of every single electrolytic capacitor in a Jupiter 8.
Many differences to the service notes. An important new resource !

https://jup8restoration.wordpress.com/2 ... jupiter-8/

Interesting to see this, but quite often manufacturers change values of Elecrolytics, not for any technical reason, but because (as a bulk purchase) they find one that's cheaper. Bear in mind that until comparatively recently value tolerance was often quoted as +100% -50%, so not exactly critical.

[Martin Walker]

Yep, spot on Folderol - power supply capacitors in particular tend not to be critical value-wise (although larger values may result in smoother supply rails as long as they physically fit into the original space), as long as their voltage rating is sufficient

However, apart from frequency-sensitive caps in other parts of the circuitry (filter tuning and so on), many others such as inter-stage coupling caps could have slightly higher value replacements that would simply extend the low frequency response of that stage.

"I stopped at the power supply but Peter continued onto the precious voice boards and changed every single cap!"

So Darren's own cap restoration didn't delve into any questionable areas :thumbup:


Martin

[DarrenGlen]

I imagine if you took a late serial Jupiter 8A they would likely have a different electro cap list again. (Certainly for the voice boards as they are a different PCB).

Its not a list of electro caps that are “wrong” so much as ones that are simply different to listed!

Cheers
Darren

[Adam Inglis]

I see these people are now making a modern SMPS replacement for the Jupiter 8 PSU..

https://synthronics.de/roland-jupiter-8-new-psu/

As the owner of a "steak grill" original jupe, I'm tempted.
I've always been a bit concerned about putting SMPSs into analogue synths, due to the noise concern, however, I haven't really been keeping up with developments in this area, and they claim this one to be "noise free".
Anyone had any experience in this area?

[Folderol]

Spec looks very good, and it seems considerable thought has gone into the design. Also modern PSUs run at such a high frequency there shouldn't be any interference issues. The additional filtering and linear regulation should eliminate any residual noise.