Vintage Synth Repair

----- Original Message -----

From: adhmzaiusz

To: vintagesynthrepair@yahoogroups.com

Sent: Wednesday, April 18, 2012 2:06 PM

Subject: [vintagesynthrepair] Progress Re: Jupiter 6 common no sound problem

Hey everyone, just wanted to mention that I've made some progress with my JP6. Since I got it I always thought it was a little strange that on the 4 voice board the slave cpu was socketed when both the other cpus werent, so I decided to pop it out and reseat it just for the heck of it. While i was at it i reseated the Roland "B" ic (i think it is a eprom) as well. When I rebooted I was surprised to see that it finished autotune after about approx 10 seconds and there was sound.
I think that when the JP6s freeze with the lfo they are locked up because they can't finish autotuning for any reason. Anyway, my 4 voice board seems to be quite messed up, almost sounds like everything is high pitched and non cv controlled. I guess that will be next on the list to sort out.

Greg

--- In vintagesynthrepair@yahoogroups.com, "adhmzaiusz" wrote:
>
> Yea, its locked up for the most part. Lfo 2 speed can still be adjusted immediately, but it seemed that after I wait a while the panel controls seem to unlock, its not perfect as it seems that the number select buttons only work 1, 6-8. So 2-5 don't work.
>
> Anyway, when I scope the reset inputs of the 3 CPUs I don't a locked voltage, which is normal. When I power on the machine i can see the voltage jump as a spike on each reset. So I'm assuming the reset works, as outlined on page 2b.
>
> My scope is only a 20mhz but i can scope the other pins of the main cpu and i see what looks like all sorts of activity looks like pulse waves etc which I assume is normal.
>
> I'm not so familiar with digital stuff, so i don't really know where to begin. I was hoping when I bought this that it would just be a failed power supply! Oh well
>
> Any further ideas? :)
>
> greg
>
> --- In vintagesynthrepair@yahoogroups.com, Malte Rogacki wrote:
> >
> > So did I get this right:
> >
> > At first the machine seems to be completely locked up?
> >
> > Then after a while the controls (buttons, LED's and so on) start to work
> > but there's still no sound?
> >
> > There's one thing to keep in mind: The processors of the voice boards need
> > their reset pulse, too. They are supplied with that pulse from the main
> > processor board. So break out the oscilloscope and measure the situation on
> > pin 9 of all three processors.
> > If you have the service manual the reset procesure and the components are
> > described on page 2b.
> >
>