All about the Roland Jupiter-series

-----Original Message-----
From: Rick Harris [mailto:rick.h@...]
Subject: [AH] Any advice on fixing a trashed Jupiter 4 ?


Hi all. I bought this very wasted-looking JP-4 for $5 at the rubbish dump.
After cleaning out the dirt, hay, dead bugs and cobwebs and replacing an IC
that was emitting smoke it's showing at least some signs of life by making
random notes and bends on its own ( sound quality of the noises is
excellent ), and very rarely responding to the keyboard. When the keyboard
is working, it always plays a low C# as well as whatever note you're
hitting.
No matter which patch button is pushed, it randomly switches between all
the sounds, but when it happens to land on 'Manual' all the controls seem
to be working. The bend/mod wheel always works. I talked to a local synth
repairer, and he said the dump was the best place for a JP-4 !
Any ideas on where to start looking for the problem ? There's no obvious
damage, but I'm guessing another IC somewhere has been barbecued. I'm
working on getting the service manual.

Cheers,
Rick.



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-----Original Message-----
From: Mike Peake [mailto:peake@...]
Subject: Re: [AH] Any advice on fixing a trashed Jupiter 4 ?

>Any ideas on where to start looking for the problem ? There's no obvious
>damage, but I'm guessing another IC somewhere has been barbecued. I'm
>working on getting the service manual.
>
>Cheers,
>Rick.

It sounds like there's still some dirt or dirty connections to deal with,
as well as some bad caps(?). The 4 is a pretty good synth, with nice,
snappy envelopes, a great filter, etc. Note that if you can't get it to
work,
the filter uses rare 'Roland' transistors and there are four fairchild
uA726 chips on the oscillator board, which go for about $45.00 each.
If there are any damaged keys, I believe that Kurt's Amps in the USA
has spares for sale: www.kurtsamps.com.

Good luck, it's a nice synth.

Mike Peake, Your Psychic Friend

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Wassup! Wazzuuup? Wussap! Wuzzzup? -Superfriends


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-----Original Message-----
From: Rick Harris [mailto:rick.h@...]
Subject: Re: [AH] Any advice on fixing a trashed Jupiter 4 ?


At 12:19 26/02/00 -0000, you wrote:

>>Any ideas on where to start looking for the problem ? There's no obvious
>>damage, but I'm guessing another IC somewhere has been barbecued. I'm
>>working on getting the service manual.
>>
>>Cheers,
>>Rick.
>
>It sounds like there's still some dirt or dirty connections to deal with,
>as well as some bad caps(?).

Now that you mention it, a couple of the ceramics on the motherboard are a
little bent over with some damage around the tops of the legs, but it looks
superficial.

The 4 is a pretty good synth, with nice,

>snappy envelopes, a great filter, etc. Note that if you can't get it to
>work,
>the filter uses rare 'Roland' transistors and there are four fairchild
>uA726 chips on the oscillator board, which go for about $45.00 each.
>If there are any damaged keys, I believe that Kurt's Amps in the USA
>has spares for sale: www.kurtsamps.com.

Thanks for your advice. The keyboard looks nice and seems mechanically in
good shape, so maybe there's something screwy in the keyboard controller
board. I'll check out the keyboard wiring with a multimeter but it looks
sound.

Cheers,
Rick.


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