All about the Roland Jupiter-series

-----Original Message-----
From: Chris [mailto:criostoir@...]
Sent: Wednesday, May 31, 2000 10:14 PM
To: analogue@...
Subject: [AH] Jupiter-6 Service Question!


I just posted a note looking for a CEM3340 chip, but I want to make sure
that would be the problem, first. If one voice of Osc-2 is dead (except for
noise), is there anything besides the CEM3340 chip for that voice that could
be bad? If so, what would be the procedure for checking it? Thanks again!
criostoir@...

-----Original Message-----
From: kennyb@... [mailto:kennyb@...]
Sent: Wednesday, May 31, 2000 10:33 PM
To: analogue@...; criostoir@...
Subject: Re: [AH] Jupiter-6 Service Question!



I would verify that the voice trigger from the CPU board is
working correctly. Make sure all of the connectors between
the 2 voice boards and the CPU board are secure. Also, the
sockets on the Jupiter-6 can sometimes allow chips to walk
out. Gently (and anti-statically) push down on all the socketed
devices to make sure they are seated correctly. If you have
steady hands and a clean repair area you may also try pulling
the chips and scraping off any oxidization with a scribe and
putting them back.

Get the service manual and follow the complete calibration
procedure to the letter. The Jupiter-6's design and layout
is fairly elegant so it is not difficult to do this.

To see if it really is your CEM chip, try swapping it with
another voice's. If the bad voice moves then you know it
is the chip.

If you find that it is the chip then do not stop there. A
healthy Jupiter-6 does not blow voice chips without permission.
You almost certainly have a power supply that is out of spec.
Check very closely with a scope the + and - power rails
on the voice boards. There should be no noise and no AC coupling.
Old capacitors on the voice board could need replacing; the
decoupling capacitors, not those in the audio path unless you
want to change the sound of your Jupiter. The CPU board
all runs off 5V but you may want to check here too.

If there is any hint of a bad power supply then get a new one
in right away. You will find power supplies are a lot cheaper
than CEM chips and a lot of problems seem to vanish with a
clean power supply.

Finally, do not replace your power supply with one of those
cute little switchers. Their cuteness hides a fatal flaw;
they are so noisy!!!!! Use only a linear power supply.

Cheers,
Kenny B.

> I just posted a note looking for a CEM3340 chip, but I want to make sure
> that would be the problem, first. If one voice of Osc-2 is dead (except

for

> noise), is there anything besides the CEM3340 chip for that voice that

could

> be bad? If so, what would be the procedure for checking it? Thanks again!
> criostoir@...
>
>

-----Original Message-----
From: Kevin Lightner [mailto:heaven@...]
Sent: Wednesday, May 31, 2000 11:26 PM
To: Analogue Heaven
Subject: Re: [AH] Jupiter-6 Service Question!


This is just MY 2 cents worth.
I'm not trying to be a jerk here.
Don't take anything personal....

> Also, the
>sockets on the Jupiter-6 can sometimes allow chips to walk
>out. Gently (and anti-statically) push down on all the socketed
>devices to make sure they are seated correctly. If you have
>steady hands and a clean repair area you may also try pulling
>the chips and scraping off any oxidization with a scribe and
>putting them back.

I've don't recall seeing sockets for the CEM's in a JP6.
If I'm wrong forgive me.

>
>Get the service manual and follow the complete calibration
>procedure to the letter. The Jupiter-6's design and layout
>is fairly elegant so it is not difficult to do this.

Calibration won't bring back a dead CEM.
Just as you wrote below that there must be a reason for a CEM to
blow, there must also be a reason to have the calibrations vary.
Quite often, people don't know how to calibrate a synth well or don't
have the proper test equipment, so advising someone to do it may
result in a synth that is more out of whack than it was before.

>
>To see if it really is your CEM chip, try swapping it with
>another voice's. If the bad voice moves then you know it
>is the chip.

Good advice, though again I don't recall any sockets in JP6's.

>
>If you find that it is the chip then do not stop there. A
>healthy Jupiter-6 does not blow voice chips without permission.

CEM's blow just for the hell of it all the time.
Especially 3360's and 3310's.
Afterall, why didn't all the others also blow? ;-)

>You almost certainly have a power supply that is out of spec.

Boo!.. wrong. Bad advice.

>Check very closely with a scope the + and - power rails
>on the voice boards. There should be no noise and no AC coupling.

Agreed.

>Old capacitors on the voice board could need replacing

Doubtful.
Tantalums -do- often fail, but their failure mode is often one where
they short.

>
>If there is any hint of a bad power supply then get a new one
>in right away. You will find power supplies are a lot cheaper
>than CEM chips and a lot of problems seem to vanish with a
>clean power supply.

Price a new JP6 power supply from Roland and I bet it'll cost a lot
more than a CEM chip from Paul or me. Putting in another supply isn't
always easy and you have to match voltage, current, temp, size, etc.
Not a simple jb to do right.

>
>Finally, do not replace your power supply with one of those
>cute little switchers. Their cuteness hides a fatal flaw;
>they are so noisy!!!!! Use only a linear power supply.

Some do, but switchers have come a LONG way.
The Andromeda uses a switcher for example.

Again, not trying to step on Ken's toes, but chances are great that
the CEM3340 itself died on that voice and little else is a problem.
Of course, support circuitry should first be checked.

K

-----Original Message-----
From: kennyb@... [mailto:kennyb@...]
Sent: Wednesday, May 31, 2000 11:47 PM
To: analogue@...; heaven@...
Subject: Re: [AH] Jupiter-6 Service Question!



Hi Kevin,

No offence taken. I am not the first owner of my Jupiter-6
and a previous owner may have socketed things. (perhaps
because CEM's blew so much ? ;)

As far as CEM's blowing, my Sequential 6-Trak definately blew
CEM's whenever it felt like it. I had always assumed that something
was causing it but I never found it. My Jupiter has not
blown one so far but I don't want to get too cocky in case
I have to come crawling back to the list looking for a CEM ;)

> >If you find that it is the chip then do not stop there. A
> >healthy Jupiter-6 does not blow voice chips without permission.
>
> CEM's blow just for the hell of it all the time.
> Especially 3360's and 3310's.
> Afterall, why didn't all the others also blow? ;-)

Hmmm.... I hadn't thought of it that way...

Thanks for your corrections,
Kenny B.

-----Original Message-----
From: Scott Fiorenz [mailto:sfiorenz@...]
Sent: Thursday, June 01, 2000 1:04 AM
To: Kevin Lightner
Cc: Analogue Heaven
Subject: Re: [AH] Jupiter-6 Service Question!


hey, while u guys are commening on the JP6 stuff
could u shed some light on my ob8 prob? :)


ok, here it is:
With both oscillators off, and keys are played-
hiss still bleeds through the outputs!
& the oscs still sound but at greatly reduced volume..
:0/

This hiss is audible even with both oscs on -
you can hear it in the background. It blends
in with the sound.
We checked all cables, connection, etc, no probs
there.. Nothing on the circuit boards appears
obviously blown. All of the chips have been
firmly pressed into place.

WOOHOO!

I've swapped out the tlo82 & 3360 on the lower
& upper boards with known good chips.
The bleedthru problem remains.

Any idea what could be causing this? It does
the same thing on upper & lower boards with
the lower board being more noticable.
Not specific to one particular oscillator.
also,
The bleedthru noise is louder in unison mode
on the lower voice board (voices 1-4)..
and is only heard whenever a key is pressed,
not constant.. hmmmm..

-----Original Message-----
From: noteit@... [mailto:noteit@...]
Sent: Thursday, June 01, 2000 1:25 AM
To: kennyb@...; analogue@...
Subject: Re: [AH] Jupiter-6 Service Question!


Hi Ken,

> As far as CEM's blowing, my Sequential 6-Trak definately blew
> CEM's whenever it felt like it. I had always assumed that something
> was causing it but I never found it.

Just a quick note to let you know that there was probably something wrong
with your Six-Trak. I've had a couple and so far have only replaced one
CEM. I have had a MAX since day one and it is still running with the
original 6 ;)


Take care,
Mike (who is now knocking on a rather large block of wood)

* NoteIt's World of MIDI *
A place for Six-Trak, Prophet 600 and FZ users
E-Mail: NoteIt@...
* http://www.geocities.com/SoHo/2163 *

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-----Original Message-----
From: Kevin Lightner [mailto:heaven@...]
Sent: Thursday, June 01, 2000 2:08 AM
To: Analogue Heaven
Subject: Re: [AH] Jupiter-6 Service Question!

>hey, while u guys are commening on the JP6 stuff
>could u shed some light on my ob8 prob? :)
>
>
>ok, here it is:
>With both oscillators off, and keys are played-
>hiss still bleeds through the outputs!
>& the oscs still sound but at greatly reduced volume..
>:0/
>
>This hiss is audible even with both oscs on -
>you can hear it in the background. It blends
>in with the sound.
>We checked all cables, connection, etc, no probs
>there.. Nothing on the circuit boards appears
>obviously blown. All of the chips have been
>firmly pressed into place.
>
>WOOHOO!
>
>I've swapped out the tlo82 & 3360 on the lower
>& upper boards with known good chips.
>The bleedthru problem remains.
>
>Any idea what could be causing this? It does
>the same thing on upper & lower boards with
>the lower board being more noticable.
>Not specific to one particular oscillator.
>also,
>The bleedthru noise is louder in unison mode
>on the lower voice board (voices 1-4)..
>and is only heard whenever a key is pressed,
>not constant.. hmmmm..

A bad cap possibly? (They commonly make tons of noise in bad MKS80's)

Have you disabled the noise source internally or used a dual trace
scope to compare the raw noise source with the output noise?
You need to verify it's not the noise source bleeding somewhere.

Have you set a scope to AC and checked the power supply rails at high
scope gain?
The noise may be on the DC rails either from a bad power supply or
another component elsewhere.

Problems like these are "divide and conquer" type probs. Isolate
sections as best you can to eliminate them as the source and home in.

A few tips anyways. :)

K

-----Original Message-----
From: Scott Fiorenz [mailto:sfiorenz@...]
Sent: Thursday, June 01, 2000 4:03 AM
To: Analogue Heaven
Subject: Re: [AH] Jupiter-6 Service Question!


hello Kevin

> >Any idea what could be causing this? It does
> >the same thing on upper & lower boards with
> >the lower board being more noticable.
> >Not specific to one particular oscillator.
> >also,
> >The bleedthru noise is louder in unison mode
> >on the lower voice board (voices 1-4)..
> >and is only heard whenever a key is pressed,
> >not constant.. hmmmm..

Kevin Lightner wrote:

> A bad cap possibly? (They commonly make tons of noise in bad MKS80's)

Which cap might this be on the OB8? Any one in particular?
Just curious. I know there are some s&h caps on the voice
cards. Might that be the problem?
Nothing appears obviously blown on any circuit boards.
Is there some way to tell aside from measuring with
scope/dvm or are these abs. necessary?

> Have you disabled the noise source internally or used a dual trace
> scope to compare the raw noise source with the output noise?
> You need to verify it's not the noise source bleeding somewhere.

Yes, the nose has been disabled from the front panel. That seems fine.
but:
oscs 1&2 bleed through both outputs even when off on front panel...
This isnt continous. Only happen when keys are pressed.
You can faintly hear the oscs when keys are played as well as
the hiss in the background, even with 1&2 + noise OFF..!
:0/
so somethings leaking (for lack of a better, more technical term..)
them through , which suxx.

> Have you set a scope to AC and checked the power supply rails at high
> scope gain?

no i dont have a scope yet unfortunately. Hope to soon though.
Open to suggestions for an accurate one that's relatively
inexpensive (under $1k). Besides, even if i had one i
wouldnt know how to do this ;) eheheheh!

> The noise may be on the DC rails either from a bad power supply or
> another component elsewhere.

So this would start @ power supply and leak all the way through
to output? im not certain what the dc rails are exactly.
R these something that is to be measured & calibrated on
the power supply? Sorry for the stoopiD questions..

> Problems like these are "divide and conquer" type probs. Isolate
> sections as best you can to eliminate them as the source and home in.

Yes i wish i was more experienced with the electronics end. Still
learning, its an ongoing process. I appreciate the suggestions
though! This is cool. Ill have something to tell the tech @
repair shop when i take it in. I *do* know how to play the
'football fight' theme from flash grodon soundtrck ;-) lol
YIPIEEEE!! "forget it ming -dales with ME" - - -
got the identical sound (the resonant bass & lead deal)
dialed up on the OB-Xa & saved as split preset. wow!
its pretty neat actually,
next one on the list to nail down is the 'batman' theme
or perhaps
"cHiPs" #o) heheheh what an epic ;)
maybe i can get a job on a cruise ship or something,
playing these over&over&over again repeatedly all day

> A few tips anyways. :)
>
> K

hey, thanks! Every little bit helps. Much appreciated.
:)
Take care,
Scott

"hmmm.. why doesn't this magnet pick up the floppy disk?"..