Vintage Synth Repair

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.
> >
>