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Broke the Jupiter 6 out of storage
#3037220 04/07/20 04:04 AM
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J. Dan Offline OP
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It's been in storage a long time - maybe 8-9 years or so? Outdoor non-climate-consoled storage facility, though at least in a case. But it certainly isn't what it was when it went in. Back when I bought it off EBay years ago, I did some repairs, borrowed an Oscilloscope and got the whole thing all tuned up and calibrated, so it was tip top when it went in.

At first I was happy it powered up and looked normal in terms of lights and stuff, but it didn't make sound. Quickly realized the presets were all gone - makes sense, battery probably died. But in manual mode, while I was able to get sound, there's some messed up stuff going on.

After playing around, the biggest issue seems to be keyboard tracking with the oscillators. I was able to get them tuned in on a single note and make everything else work roughly correct in terms if EGs, LFOs, filter, etc.

Random notes don't trigger on the keyboard, but not the same note in each octave, and what's really odd is some notes will trigger one osc but not the other. Seems like some of this may be different depending if I select poly 1 or poly 2 for key mode. Keyfollow all over the place making it in no way playable. Arpeggiator seems to trigger only a few notes of an arpeggio.

So I haven't opened it yes, but doesn't seem like it will be as simple as cleaning key contacts or recalibrating the oscillators. Need to track down the service manual again...had it saved on an old computer that crashed. May need to find someone to borrow another O-scope from for a weekend.


Dan

Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.
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Re: Broke the Jupiter 6 out of storage
J. Dan #3037222 04/07/20 04:31 AM
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sound like a fun project, Dan.


A reason why I collect old keyboards is that I feel partly responsible for doing it, responsible for preserving history and being a custodian for these things
Plus, old gear has a story. I like that.
Re: Broke the Jupiter 6 out of storage
davedoerfler #3037224 04/07/20 04:55 AM
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Originally Posted by davedoerfler
sound like a fun project, Dan.

Would have been a lot more fun it I could have just started jamming on it and not have to fix it! Lol.


Dan

Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.
Re: Broke the Jupiter 6 out of storage
J. Dan #3037228 04/07/20 05:42 AM
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Well, I hope your soldering skills are up to snuff! I grew up in Kirkwood, so I know that after 9 years, that thing's been through some extreme termperature & humidity changes.
Things have been expanding, contracting & corroding. At the very least you'll need to clean & re-seat every connector, and do a really good inspection of all solider joints - you'll probably need to re-flow some.
Anyhow, I hope you have some good luck with it - keep us posted!

Last edited by S_Gould; 04/07/20 05:43 AM.
Re: Broke the Jupiter 6 out of storage
J. Dan #3037351 04/07/20 08:19 PM
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After several years on non-use, my Jupiter 6 is also not working. It won't even boot up, even though it was working perfectly when I put it in the basement. It's been at room temperature all it's life, so don't know what's up.

Best of luck with your project Dan. Mine is going to have to go to a tech.

Re: Broke the Jupiter 6 out of storage
J. Dan #3037358 04/07/20 09:02 PM
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Maybe try the guys at Syntaur - they restored a Jupiter 4 (haha even added an after touch function!) https://www.youtube.com/watch?v=QNaMv9CAuPg


The trouble with doing the job correctly first time, is no-one will ever know just how difficult it was.
Re: Broke the Jupiter 6 out of storage
J. Dan #3037668 04/09/20 12:00 AM
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Haven't had time to start working on this yet, just left it powered up for a while and started doing filter sweeps, lol. The filter sounds great!

Anyway, the key tracking is still off but seems to have improved SOME all on its own. It seemed like more keys weren't working and at first I was thinking my first action would be to clean all the key contacts. But then I switched from Poly-1 mode to poly-2 and they worked. Switched back to poly-1 and keys that didn't work did, but others didn't. Final observation is that switching between poly modes continues to change which keys work and which dont including some that only trigger one osc, not both. So I don't think it's a key contact issue at all.

Need to dig up that service manual and look at the schematics before I decide where to start. Even in its state as being musically unplayable, it still makes some really nice sounds!


Dan

Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.
Re: Broke the Jupiter 6 out of storage
J. Dan #3037694 04/09/20 01:45 AM
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The fella Mims at Syntaur actually says in his vids that he is happy to chat with folks and try and help out long distance with issues they may have with vintage gear...anyhoo, it was just a thought smile


The trouble with doing the job correctly first time, is no-one will ever know just how difficult it was.
Re: Broke the Jupiter 6 out of storage
J. Dan #3037709 04/09/20 02:32 AM
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Appreciate that. I'm not there yet. If I need to bother him I will.


Dan

Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.
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Re: Broke the Jupiter 6 out of storage
J. Dan #3037717 04/09/20 02:39 AM
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btw, I'm envious of you, having such a classic 'board! Listening to him reno the 4 brought back memories of those sounds! Modern gear gets close, for sure, but they (4's 6's and 8's) were all just a bit more, hmmm, "raw'er" if you get me.


The trouble with doing the job correctly first time, is no-one will ever know just how difficult it was.
Re: Broke the Jupiter 6 out of storage
J. Dan #3037727 04/09/20 03:29 AM
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So a little background:

I once had a FLAWLESS Jupiter 6 that I actually gigged with. I got the Europa expansion (look it up). It got stolen around 2002 or so. The folks who make the Europa expansion were kind enough to flag their firmware so that if anybody ever tries to upgrade that keyboard or get support, they'll be alerted. But realistically, how would anybody know it had the upgrade in the first place? So I bought another one not in as good shape. Already had many of the chips replaced, some were bad when I got it. Thanks to Wime County Productions, I replaced the bad vintage chips, borrowed a scope, and got it tip top. Stopped gigging with it, ended up in storage during my divorce, and here we are.


Dan

Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.
Re: Broke the Jupiter 6 out of storage
J. Dan #3037729 04/09/20 03:30 AM
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I more or less with the right equipment and time and patience can fix these.


Dan

Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.
Re: Broke the Jupiter 6 out of storage
J. Dan #3037779 04/09/20 01:55 PM
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pics

sorry, Dan. Could't resist. wink


A reason why I collect old keyboards is that I feel partly responsible for doing it, responsible for preserving history and being a custodian for these things
Plus, old gear has a story. I like that.
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Re: Broke the Jupiter 6 out of storage
J. Dan #3037896 04/09/20 09:42 PM
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I'll get some pics up later tonight.

After playing various combinations of things in different key modes, I'm becoming fairly certain that 3 oscillators are not working and the strange behavior is due to the order that the different modes select which oscillator to trigger. It becomes fairly clear in Unison and Poly-2 modes. Poly-1 seemed random with some notes working or not, sometimes only one osc, others 2. But in particular, Poly-2 seemed fairly repeatable.

I assigned an LFO to OSC 2 only so that as I hit notes I could hear clearly if it was one or the other or both that was triggering. The JP6 is 6 voice Poly with 2 osc per voice for a total of 12 osc. In Poly-2 mode it triggers the voices in the same order every time (Poly-1 cycles through them). I made a chart and recorded what was triggering and what was not and came up with these results.

Voice 1, OSC 1 & 2 good
Voice 2, OSC 1 good, 2 bad
Voice 3, OSC 1 & 2 bad
Voice 4, OSC 1 & 2 bad
Voice 5, OSC 1 & 2 good
Voice 6, OSC 1 & 2 good

So without even opening it up, I've narrowed it down to 5 of the 12 oscillators not sounding, and know which 5 it is. That will tell me directly where to look when I open it up.


Dan

Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.
Re: Broke the Jupiter 6 out of storage
J. Dan #3037901 04/09/20 09:51 PM
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With time, patience, a manual and part I still could not fix it. This is why I don't buy a Chroma. I don't have a decent keyboard tech within 200 miles. Good luck with this. These old keyboards are special. The people that manage to keep them going are special.


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Re: Broke the Jupiter 6 out of storage
J. Dan #3037934 04/09/20 11:36 PM
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Originally Posted by J. Dead
So without even opening it up, I've narrowed it down to 5 of the 12 oscillators not sounding, and know which 5 it is. That will tell me directly where to look when I open it up.

And the beauty of a design like that is you have multiple good circuits to make voltage comparisons in the absence of a schematic.

I always lusted after a Jupiter 6 when it was a current model, but never got one.

Last edited by Mike Warren; 04/09/20 11:38 PM.

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Re: Broke the Jupiter 6 out of storage
davedoerfler #3037938 04/09/20 11:53 PM
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[Linked Image][Linked Image]
Originally Posted by davedoerfler
pics

sorry, Dan. Could't resist. wink


Dan

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Re: Broke the Jupiter 6 out of storage
J. Dan #3037955 04/10/20 01:43 AM
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You probably already know this, but based on the age and the fact that multiple problems exist, I'd strongly suspect electro caps. But I have no specific experience with the JP6.


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Re: Broke the Jupiter 6 out of storage
J. Dan #3037962 04/10/20 02:00 AM
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Originally Posted by J. Dead
[Linked Image][Linked Image]
Originally Posted by davedoerfler
pics

sorry, Dan. Could't resist. wink
ahh a thing of beauty!!


The trouble with doing the job correctly first time, is no-one will ever know just how difficult it was.
Re: Broke the Jupiter 6 out of storage
Mike Warren #3037976 04/10/20 03:12 AM
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Originally Posted by Mike Warren
You probably already know this, but based on the age and the fact that multiple problems exist, I'd strongly suspect electro caps. But I have no specific experience with the JP6.


Yep, no electrolytics as part of the VCO/VCF/VCA circuits, only power supply. Voice boards largely use Tantalum capacitors with some ceramic disk and some Mylar. Checked supply voltages at each of the voice boards and they're all good. Ribbon cables are all tight. Some of the chips have been replaced over the years (some by me) and use IC sockets rather than being directly soldered to the board so I suspected that as a possibility but they all seem tight.

Next step will be to identify on the boards themselves specifically which voices are the offending ones, then trace signal through VCO-VCF-VCA. The circuit boards are marked pretty clearly making it fairly easy to identify what's where, but I'm still getting to the point where I need that service manual to verify what I should be seeing at each test point.

One other thing - there is a main CPU board that handles input from the panel, keyboard scanning, patch storage etc. Then there are 2 voice boards. Each one is identical and can support up to 4 voices, except one of them basically is just stuffed with half the components so it is only 2 voices. Each board has a slave processor that ties to the main board and controls the voices on it's board. So 4 + 2 gives the 6 voices. In split mode, you can select if you want 4 on bottom, 2 on top, or vice versa. So guess what? in split mode I can play and determine which board is doing what. Doing so, I determined that the 2 voice board is working as it should. The 4 voice board is the one that has 2 completely non working, and 1 that only has VCO 1 sounding (and one that is fine). So that will be my focus.

EDIT:

Here is the 4 voice board. You can see on the left side the slave processor (silver square) and circuitry to generate all the CV/Gate signals. Then clearly labeled columns for VCO 1 and VCO 2 and voices labeled in rows A, B, C, D. Moving to the right are the Filter sections and VCA. VCA sections are paired up with a CEM3360 dual VCA chip. Since both voice C and D don't work on that board, the CEM3360 for VCA C,D is my primary suspect. When it comes to VCA A,B, Voice A sounds fine and Voice B only sounds VCO 1 not 2. That means it's making through the filter and VCA. So it would have to be either voice B, VCO 2, or possibly the voice mixer circuit for VCO 2, or one of the associated CV's or gates. So getting things narrowed down pretty close I think.

[Linked Image]

Miden - there ARE a couple non-polarized electrolytics as part of the VCA (probably for DC blocking) so that in fact COULD be a culprit as well...but I doubt it because there is still a separate cap for each of the 2 VCA's and both would have to be out for that dual VCA while none of the others are out. Also, I just noticed that the CEM2260 for VCA C,D is warmer to the touch (not hot, just warmer) than the one for VCA A,B.

Last edited by J. Dead; 04/10/20 05:41 AM.

Dan

Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.
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Re: Broke the Jupiter 6 out of storage
J. Dan #3038010 04/10/20 06:19 AM
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If it in fact needs the (discontinued) Curtis CEM3360 to be replaced, does anybody have any experience with the reportedly pin for pin replica AS3360? In the US they're only around $10 while I'm seeing listings for the original Curtis Chips in the $45 range.


Dan

Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.
Re: Broke the Jupiter 6 out of storage
J. Dan #3038014 04/10/20 06:56 AM
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Separate issue, gonna have to replace the battery as well. All the patches were blank when I powered up. I saved some and while it's powered up they recall, but even just a short power cycle and they are gone. It's a soldered in battery - not sure if it's still available or a modern equivalent or retrofit. Guess I'll do some googling unless somebody here has suggestions.



[Linked Image]

Last edited by J. Dead; 04/10/20 06:57 AM.

Dan

Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.
Re: Broke the Jupiter 6 out of storage
J. Dan #3038035 04/10/20 11:12 AM
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Originally Posted by J. Dead
You can see on the left side the slave processor (silver square)

Do you mean the IC with the Roland sticker? FWIW (probably nothing relevant for the discussion - blush) it is an EPROM. The processor is right below, an Intel 8031, prom-less version of the 8051.

Last edited by EVC; 04/10/20 11:16 AM.
Re: Broke the Jupiter 6 out of storage
J. Dan #3038047 04/10/20 12:08 PM
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Originally Posted by J. Dead
If it in fact needs the (discontinued) Curtis CEM3360 to be replaced, does anybody have any experience with the reportedly pin for pin replica AS3360? In the US they're only around $10 while I'm seeing listings for the original Curtis Chips in the $45 range.

Bought a bunch of these for my Memorymoog but haven't needed them yet. IIRC I tried one out briefly and it was fine.

Btw in case you didn't find it yet..,
JP6 Service Manual

Re: Broke the Jupiter 6 out of storage
J. Dan #3038061 04/10/20 12:43 PM
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Originally Posted by J. Dead
Voice boards largely use Tantalum capacitors with some ceramic disk and some Mylar.

Dipped tantalums of that age were notorious for going short. Best to check them before ordering replacement chips. Not that I can see any in that pic. The orange capacitors look more like mylars, but perhaps it's just the camera angle.

A couple of other things I notice; as someone who lays out PCBs for a living, that PCB layout is ugly. Admittedly, that sort of thing was quite common in those days. At least they labelled the sections. I also notice a typo in the silk screen. Slave CUP should be slave CPU. smile


Quote
Also, I just noticed that the CEM2260 for VCA C,D is warmer to the touch (not hot, just warmer) than the one for VCA A,B.

That doesn't bode well for it.


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