Vintage Synth Repair

Cool...I fixed the problem with the 'voice' pre-set and it's one you
might want to write in your 'factory anomalies' section..my hunch
(below) was right..I soldered in the 'missing from factory' Trimmer 31
VCF INV control..plus an also 'missing from factory' 100 ohm resistor
in the same circuit..and all this seems to do is adjust the VCF for
the 'voice' pre-set sound.. you can then balance up the waveform
nicely now :o)

This, as far as I know, only works with the final E revision of the
module boards..I could be wrong but I've had enough of staring at the
JP4 pdf for a while!

Just waiting for the replacement BA662 to cure the annoying click..and
 she should be firing on all cylinders!

Phil.


> > Still looking into this 'voice' pre-set low volume problem..it's like
> > a fifth of the volume of the rest of the presets...the later module
> > boards had a trimmer fitted called VCF INV trimmer no. 31 that was
> > just to adjust the 'Voice' pre-set waveform..mine hasn't got it but
> > has the holes for a trimmer to be soldered in...maybe it's a factory
> > anomaly?



--- In vintagesynthrepair@yahoogroups.com, "eggwheatis"
<eggwheatis@...> wrote:
>
> Ok fixed the bender circuit...
> 
> The problem with the 'voice' pre-set sound is that the calibrations
> make the separate module board VCF trimmer settings too low. That's
> why it's quiet..the filters set too low..you only have to raise the
> VCF slightly with the bender and all is well..but according to the
> calibration it's set perfectly.. 
> 
> I just ordered a BA662 from vintage planet..17 euros each...
> 
> Have to say my Jupiter 4 is already sounding great though!
> 
> Phil.
> 
> 
> --- In vintagesynthrepair@yahoogroups.com, "eggwheatis"
> <eggwheatis@> wrote:
> >
> > 
> > Quick update: Yep IC16 the BA662 is definitely bad so I need to source
> >  one or a BA6110 if I cant get them. The 6110 looks like it'll be ok
> > just has a different pinout.
> > 
> > Still looking into this 'voice' pre-set low volume problem..it's like
> > a fifth of the volume of the rest of the presets...the later module
> > boards had a trimmer fitted called VCF INV trimmer no. 31 that was
> > just to adjust the 'Voice' pre-set waveform..mine hasn't got it but
> > has the holes for a trimmer to be soldered in...maybe it's a factory
> > anomaly?
> > 
> > Oh yeh and Ive just found that the bender doesnt seem to work at
all...
> > 
> > Phil.
> > 
> > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis"
> > <eggwheatis@> wrote:
> > >
> > > Hi guys, just calibrated my Jupiter 4 using the service data and a
> > > scope..well it all sounds great now except for the preset 'Voice'
> > > sound, it's very quiet. All the other presets are nicely
balanced and
> > > sound correct except for this one's level. I've been back through my
> > > calibrations 3 times over and everything looks perfect. Anyone know
> > > anything about this?
> > > 
> > > Also I have a click at the start of one of the notes, I've traced it
> > > down to one of the module boards..and looking at the schems it looks
> > > like IC16 a Roland custom BA662 is the culprit. Is there a
source for
> > > these anywhere? UK preferably..Also I've read conflicting
information
> > > about the BA6110 being a suitable replacement..can't find a
definitive
> > > answer though.. again any info would be helpful.
> > > 
> > > Thanks, Phil.
> > >
> >
>