[sdiy] PAiA 2720/R rebuild

Michael E Caloroso mec.forumreader at gmail.com
Mon Oct 27 01:12:53 CET 2014

PAiA loved those sucky 748 opamps.  Ideal candidate for upgrades.  I
did that with my 4700 modular that I built back in 1981.


On 10/26/14, Dave Brown <davebr at earthlink.net> wrote:
> He didn't on this one.  I've never seen so much flux all over everything.
> Leads extended through quite far, were bent over, and about 3X too much
> solder was used.  I don't think it was acid core solder but it had about
> that much flux on it.  I ended up sucking every pad and resoldering and
> fixing the pads that had lifted.  I think the sheer weight of the solder on
> the underside was enough to lift the pads!
> Dave
> -----Original Message-----
> From: David G Dixon [mailto:dixon at mail.ubc.ca]
> Sent: Sunday, October 26, 2014 3:59 PM
> To: 'Dave Brown'; synth-diy at dropmix.xs4all.nl
> Subject: RE: [sdiy] PAiA 2720/R rebuild
> Wow!  Looks great!  That was on my Christmas wish list from the age of 12
> (I
> turn 50 on Wednesday).  Santa never brought it.  I did try to build a Gnome
> with a friend in 1976, and failed utterly (he actually bought it, and was
> too impatient to use flux with the solder - every solder joint was stone
> cold).  I didn't attempt Synth DIY again until 2008.  Now, of course, I
> look
> at the PAiA stuff, and can't believe how cheap it looks and how simple it
> is.
>> -----Original Message-----
>> From: synth-diy-bounces at dropmix.xs4all.nl
>> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Dave Brown
>> Sent: Sunday, October 26, 2014 2:00 PM
>> To: synth-diy at dropmix.xs4all.nl
>> Subject: [sdiy] PAiA 2720/R rebuild
>> In case anyone is interested, I just was given a PAiA 2720/R synth
>> that I decided to restore.  A lot of the work was improving the
>> construction techniques of the original builder and dealing with the
>> general degradation of the electro-mechanical parts over time.  There
>> is a list on the site but the biggest issue was rebuilding the Pratt
>> and Read keyboard which meant everything had to be disassembled.  The
>> wood cabinet needed some TLC but the only improvements that I made
>> were the increase in PS filter caps and the replacement of just a
>> handful of parts.  Most all the wiring and soldering though had to be
>> redone and it required a lot of cleaning.  The keyboard S&H could
>> benefit from a modern op-amp but I decided to keep it original.
>> Photos and information at
>> http://modularsynthesis.com/paia/2700/2700.htm
>> David J. Brown
>> Email davebr at earthlink.net
>> Website http://modularsynthesis.com
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