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Old Roland Jupiter 8 restoration

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Re: Old Roland Jupiter 8 restoration

Postby Folderol » Mon Jul 08, 2019 2:53 pm

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.
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Re: Old Roland Jupiter 8 restoration

Postby Martin Walker » Mon Jul 08, 2019 3:28 pm

Folderol wrote: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:


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Re: Old Roland Jupiter 8 restoration

Postby DarrenGlen » Tue Jul 09, 2019 12:57 am

Folderol wrote:
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
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Re: Old Roland Jupiter 8 restoration

Postby Hugh Robjohns » Tue Jul 09, 2019 10:33 am

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!

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Re: Old Roland Jupiter 8 restoration

Postby DarrenGlen » Sat Jul 20, 2019 12:49 am

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/
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Re: Old Roland Jupiter 8 restoration

Postby Folderol » Sat Jul 20, 2019 6:51 am

DarrenGlen wrote: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.
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Re: Old Roland Jupiter 8 restoration

Postby Martin Walker » Sat Jul 20, 2019 8:46 am

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:


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Re: Old Roland Jupiter 8 restoration

Postby DarrenGlen » Tue Jul 23, 2019 12:19 am

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!

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Re: Old Roland Jupiter 8 restoration

Postby Adam Inglis » Tue Aug 13, 2019 12:05 am

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?
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Re: Old Roland Jupiter 8 restoration

Postby Folderol » Tue Aug 13, 2019 7:36 am

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.
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Re: Old Roland Jupiter 8 restoration

Postby DarrenGlen » Wed Aug 14, 2019 12:28 am

Adam Inglis wrote: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?

I am receiving the first one of these off the production line. Cora will be the first to receive this new PSU transplant. There will be several blog posts on it as I progress! It will be interesting stay tuned!!
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Re: Old Roland Jupiter 8 restoration

Postby Adam Inglis » Wed Aug 14, 2019 12:48 am

Thanks Darren - eagerly awaited!

One other concern I have is the longevity of SMPSs compared to linear PSUs. I have had to replace the SMPS in synths such as a Korg M1R, a Proteus 2, and an Ultraproteus, several times over a decade or more, however the linear supplies in say, the jupe, and a bunch of my analogues from late 70s/early 80s just seem to keep on truckin'. Sure, they get hot and a component (often an electro cap) may fail, but that's just a matter of replacing the component. With SMPS, they're really difficult to fault-find, and you can't test them unloaded, so usually it's a case of replacing the whole unit.
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