Vintage Synth Repair

Well, it may appear I've run into a potential happy mistake.  Today when I tried my next attempt to get my JP6 on its feet, I realized that yesterday when I replanted the slave cpu pin#1 was bent right out and not even in the socket.  So I fixed it and plugged it back in, and what do you know it locks up again.  So i bent back pin 1 again to see what happens, and what do you know it unlocks itself without pin 1 plugged in.  So strange.  I then replaced the level shifter IC10 (MC14504) figuring maybe it was all stuck high, but still no difference.  Otherwise, I guess I should just continue following where pin 1 goes, to the 4051 and next the TL064.  Somehow though, I think my luck just isn't that great to accidentally bend just the right pin back that is causing the problem.  We shall see, we shall see.

Greg

--- In vintagesynthrepair@yahoogroups.com, "jammie" <jammie.emma@...> wrote:
>
> check the cv dac and the sample and hold multiplexers
>   ----- 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" <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 <gacki@> 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.
>   > >
>   >
>