Vintage Synth Repair

> 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
> 



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