Found a cheap jupiter 4 (3 voices working)

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Composition86
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Found a cheap jupiter 4 (3 voices working)

Post by Composition86 » Tue Mar 10, 2009 11:06 am

Hi, I have found an half priced Jupiter 4 in very good cosmetic conditions, but seller says that:
by pushing the same key for 4 times, there are 3 notes which are ok and the 4th sounds around an octave lower. It also happens in poly mode.

The synth, in these conditions, should be a full working 3-phonic synthesizer, isn't it?

Which could be the damage? Is it just a question of properly setting the tune's potentiometers on the back (may be with a voltmeter or an oscilloscope) or is there the possibility to have a serious damage? Thanks.

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Re: Found a cheap jupiter 4 (3 voices working)

Post by guesswho » Tue Mar 10, 2009 12:36 pm

The card isn't seated properly. I'd buy it. Sit the JP on the floor and lift it about 6 inches on the right side and drop it. The card will seat and you will have all 4 voices in tune again.
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Re: Found a cheap jupiter 4 (3 voices working)

Post by Composition86 » Tue Mar 10, 2009 1:25 pm

Seriously? :lol:

Ok, could be the voice card in the best hypothesis, but it could be also a component which needs to be replaced, do you agree? My main fear is that the synth has a problem regarding the internal chip, if so... #-o

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Re: Found a cheap jupiter 4 (3 voices working)

Post by Umbe78 » Tue Mar 10, 2009 5:48 pm

hi!
io ho lo stesso problema sul mio... è più complicato di cosi, può funzionare bene con 3 voci come "male" con 1 .. uno dei 4 oscillatori è andato ...
poly 1 e 2 e unison 1 e 2 sono diversi modi di applicare gli oscillatori (poly 1 ad ogni nota premuta cambia l'oscillatore) ... cmq è suonabilissimo per me ... se ti interessa io vendo un JP8000
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Re: Found a cheap jupiter 4 (3 voices working)

Post by Composition86 » Tue Mar 10, 2009 7:01 pm

Ciao, ti ringrazio per la risposta. Ti mando un PM.

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Re: Found a cheap jupiter 4 (3 voices working)

Post by killedaway » Tue Mar 10, 2009 7:21 pm

guesswho wrote:The card isn't seated properly. I'd buy it. Sit the JP on the floor and lift it about 6 inches on the right side and drop it. The card will seat and you will have all 4 voices in tune again.
you have to be joking. that is single-handedly the worst bit of advice i have ever heard.
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Re: Found a cheap jupiter 4 (3 voices working)

Post by guesswho » Tue Mar 10, 2009 10:01 pm

killedaway wrote: you have to be joking. that is single-handedly the worst bit of advice i have ever heard.
NO, I'm dead serious. This is what was recommended to me by a fellow named Jim Nelson after just having him service my JP-4. He worked for Roland Canada's service department and is actually responsible for setting their service department up back in the late 70's/early 80's. I thought he was shitting me - until I tried it. I started with a low height, maybe 2-3 inches and it didn't realy do s**t. Went the whole 6 inches, and haven't had an issue with voices going out of tune since (knock on wood).

And just so that you know this guy, Jim, is not just some schmuck with a soldering iron, anyone that has called Roland Canada's service department needing repairs to old gear (gear that they no longer have parts for) will be given Jim's number. May I ask, do you have a JP-4 or do you do circuit board repair?
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Re: Found a cheap jupiter 4 (3 voices working)

Post by killedaway » Tue Mar 10, 2009 10:09 pm

guesswho wrote:May I ask, do you have a JP-4 or do you do circuit board repair?
no, but i bet if i did, business would be pretty lucrative if people followed that guy's advice. i don't have to be a JP4 owner nor a repair professional to know that dropping fragile electronic components from any height is a bad idea. that's just bush-league.
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Re: Found a cheap jupiter 4 (3 voices working)

Post by Composition86 » Tue Mar 10, 2009 10:31 pm

I understood.
The advice about the voice card is good, but I think that a better and cleaner way to set it right must exist. :wink:

I know it's difficult, but other opinions are welcome, expecially from jp4's owners. If I will decide to buy I would like to know what to do, if possible.

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Re: Found a cheap jupiter 4 (3 voices working)

Post by guesswho » Tue Mar 10, 2009 10:46 pm

killedaway wrote:i don't have to be a JP4 owner nor a repair professional to know that dropping fragile electronic components from any height is a bad idea.
This stuff isn't as fragile as you think. Just imagine how many feet some of these things were dropped back when they were made and shipped here from over seas!
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Re: Found a cheap jupiter 4 (3 voices working)

Post by Steve Jones » Fri Mar 13, 2009 5:06 am

The voice cards are screwed down anyway, dropping a JP4 is absolutely the worst thing you can do. They are poorly built in the first place, the PCB tracks on the top panel board are super thin and will crack all along the earth traces if you even look at them the wrong way, the solder joints on the sliders are sub-standard and liable to cracking, the heavy card cage with the voice cards and card controller board is sitting on top of a fragile mother board, and the key contacts are very fragile. Do not drop it. you will break things. Any tech that tells you to pick up a JP4 and drop it should find another career.

If you want to re-seat the voice cards simply open the top, undo the phillips head screws on each card and gently remove and replace it. The blade connecters are fragile, make sure that you align them properly, you will need a flashlight and to be gentle. Please do not trash your synth by hitting it or dropping it.

JP4's must have been made by Roland's evil clone twin on another planet. Unlike other roland gear of the time, they are badly built, fragile, messy and unreliable. They are hard enough to keep going when they are looked after, deliberately dropping them is insanity.
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Re: Found a cheap jupiter 4 (3 voices working)

Post by Composition86 » Fri Mar 13, 2009 10:54 am

So they're fragile. #-o

The strange things are: is it possible that a screwed voice card can move from its position?
And second thing: how this would make it sounds one octave lower than the others?
I thought that a damaged component would be more realistic, but I'm not a technician.

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Re: Found a cheap jupiter 4 (3 voices working)

Post by Steve Jones » Fri Mar 13, 2009 11:38 am

A voice card could move if the screws were missing from the top lugs, and it could cause tuning issues. They are complicated machines to fix, there is a lot of routing going on between the voice cards, the motherboard, the voice controller card (the front card in the cage), and the key decoder board beside the mother board. To work on a voice board while it is powered up you need an extender card to lift it above the card cage to be able to take measurements from it. They are not for the faint hearted to repair, but they do sound good when they work. They had lots of revisions, Roland radically changed the voice cards, so even back then there were all kinds of reliability issues that made Roland have to re-design things over and over.

If it is not working properly and it is complete, ie:not missing any cards, then I would buy it if it is very cheap, and factor in the final coat of having a tech repair it. I wold not suggest spending a lot of money on a faulty JP-4, because the final cost to get it working and calibrated could be too much.
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Re: Found a cheap jupiter 4 (3 voices working)

Post by Composition86 » Sat Mar 14, 2009 11:37 am

Ok, this unreliability could be a reason why their price is quite low, thanks for the advice.

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Re: Found a cheap jupiter 4 (3 voices working)

Post by guesswho » Sat Mar 14, 2009 7:07 pm

Regardless, I bought mine broken. Probably the worst state one could ever be in. I paid $200 and invested another $500 in repairing it. Within a day it was out of tune. I did as suggested and it has never gone out of tune again. Had any of you nay-sayers been my tech, I'd have a synth that was still out of tune.
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