Vintage Synth Repair

On some patches, starting at the bottom of the keyboard, every 4th key
fails to sound for an octave or two.  On other patches, every 4th
white key fails to sound for an octave or two. Most patches are ok. 
Ideas?

Hi There,

It sounds like you have a voice failing. This might need some serious 
measurement to understand what exactely is wrong. You should get yourself a 
service manual to proceed with (conducted) measurements.

If you can't do this yourself you should probably take your JP8 to a repair 
shop or a technician who has worked on JPs before.

I've had a similar problem on my unit a few years ago; it appeared that the 
custom VCA-IC had reached the end of its lifetime... It wasn't easy to find 
a spare IC.

Hopes this works out for you.

Cheers,
RVe



"If Pac Man affected us as kids, we'd all run around in a darkened room, 
munching pills and listening to repetitive music." - Kristian Wilson, 
Nintendo, Inc, 1989.

>From: "tim_at_jonas" <tim@...>
>Reply-To: vintagesynthrepair@yahoogroups.com
>To: vintagesynthrepair@yahoogroups.com
>Subject: [vintagesynthrepair] Jupiter 8 Problem
>Date: Mon, 13 Feb 2006 22:43:07 -0000
>
>On some patches, starting at the bottom of the keyboard, every 4th key
>fails to sound for an octave or two.  On other patches, every 4th
>white key fails to sound for an octave or two. Most patches are ok.
>Ideas?

Doesn't the JP8 use descrete circuity for the VCA/VCF ?


--- In vintagesynthrepair@yahoogroups.com, "Ricardo Verschut @ Jura 
Music Productions / The Engine Room" <juramp@...> wrote:
>
> Hi There,
> 
> It sounds like you have a voice failing. This might need some 
serious 
> measurement to understand what exactely is wrong. You should get 
yourself a 
> service manual to proceed with (conducted) measurements.
> 
> If you can't do this yourself you should probably take your JP8 to 
a repair 
> shop or a technician who has worked on JPs before.
> 
> I've had a similar problem on my unit a few years ago; it appeared 
that the 
> custom VCA-IC had reached the end of its lifetime... It wasn't easy 
to find 
> a spare IC.
> 
> Hopes this works out for you.
> 
> Cheers,
> RVe
> 
> 
> 
> "If Pac Man affected us as kids, we'd all run around in a darkened 
room, 
> munching pills and listening to repetitive music." - Kristian 
Wilson, 
> Nintendo, Inc, 1989.
> 
> 
> >From: "tim_at_jonas" <tim@...>
> >Reply-To: vintagesynthrepair@...m
> >To: vintagesynthrepair@yahoogroups.com
> >Subject: [vintagesynthrepair] Jupiter 8 Problem
> >Date: Mon, 13 Feb 2006 22:43:07 -0000
> >
> >On some patches, starting at the bottom of the keyboard, every 4th 
key

> >fails to sound for an octave or two.  On other patches, every 4th
> >white key fails to sound for an octave or two. Most patches are ok.
> >Ideas?
>