Vintage Synth Repair

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.

On Friday 18 April 2008 10:43, 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.

I don't think that's a "Roland custom" part,  I believe that it's probably 
made by Rohm.  I don't seem to have a datasheet on it yet,  though.  There 
seems to be some info on it here:

http://www.synthdiy.com/show/?id=2270

According to the info on that page there might be an issue with DC offset, and 
the pinout given doesn't seem to show any offset adjustment pins.  If there's 
a "balance" or similar adjustment n the module board that's givnig you the 
click try that and see if it gets you anywhere,  if there isn't one there it 
should be possible to add one without too much trouble.

> Is there a source for these anywhere? UK preferably.

I'm not seeing anything in my searches so far except for one place that 
claimed they could get them but has a $75 miniumum order per line item.

> .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. 

I believe the link above also touches on that,  too.  I do have a datasheet 
available for at least one version of the BA6110,  to be found through 
http://www.classiccmp.org/rtellason/parts-index.html with the exact part 
number for what I have being BA6110FS (I assume that the FS applies to case 
style, maybe).

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

> According to the info on that page there might be an
> issue with DC offset, and 
> the pinout given doesn't seem to show any offset
> adjustment pins.  If there's 
> a "balance" or similar adjustment n the module board
> that's giving you the 
> click try that and see if it gets you anywhere,  if
> there isn't one there it 
> should be possible to add one without too much
> trouble.

Thanks Roy, yes it is indeed an issue with DC offset
and there is a trimmer to adjust out the click on each
module board.  The trouble is on this one module board
you cannot adjust it out...There is definitely a fault
there I found a short in the circuit, not found
exactly whats causing it yet..am working on it now..

Phil.

--- "Roy J. Tellason" <rtellason@...> wrote:

> On Friday 18 April 2008 10:43, 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.
> 
> I don't think that's a "Roland custom" part,  I
> believe that it's probably 
> made by Rohm.  I don't seem to have a datasheet on
> it yet,  though.  There 
> seems to be some info on it here:
> 
> http://www.synthdiy.com/show/?id=2270
> 
> According to the info on that page there might be an
> issue with DC offset, and 
> the pinout given doesn't seem to show any offset
> adjustment pins.  If there's 
> a "balance" or similar adjustment n the module board
> that's givnig you the 
> click try that and see if it gets you anywhere,  if
> there isn't one there it 
> should be possible to add one without too much
> trouble.
> 
> > Is there a source for these anywhere? UK
> preferably.
> 
> I'm not seeing anything in my searches so far except
> for one place that 
> claimed they could get them but has a $75 miniumum
> order per line item.
> 
> > .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. 
> 
> I believe the link above also touches on that,  too.
>  I do have a datasheet 
> available for at least one version of the BA6110, 
> to be found through 
> http://www.classiccmp.org/rtellason/parts-index.html
> with the exact part 
> number for what I have being BA6110FS (I assume that
> the FS applies to case 
> style, maybe).
> 
> -- 
> Member of the toughest, meanest, deadliest, most
> unrelenting -- and
> ablest -- form of life in this section of space,  a
> critter that can
> be killed but can't be tamed.  --Robert A. Heinlein,
> "The Puppet Masters"
> -
> Information is more dangerous than cannon to a
> society ruled by lies. --James 
> M Dakin
> 



      ___________________________________________________________ 
Yahoo! For Good helps you make a difference  

http://uk.promotions.yahoo.com/forgood/

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.
>

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.
> >
>

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.
> > >
> >
>