Re: Modification question (long)

[bpb@bpbsn.cca.rockwell.com (Brad Baker)]

Rick Prevallet <rickp@tyrell.net> writes:

  > Hi Folks, I read quite a while back about someone (Brad?) taking
  > the percussion unit off an M3 and installing it in a BV/CV organ.
  > If that person is still around I'd like to discuss that
  > conversion.

  > I have found an M3 that is in pretty good shape except for the
  > amplifier section (it is not very loud).  The price is $120.
  > Normally I'd not consider canibalizing an (almost) working unit,
  > but I'd like to put percussion on one of my CVs.

  > Thanks for any help.

  > RickP@Tyrell.Net

rick,

here's the history of the converted b3 i own. it includes the m3
percussion modification. if you wish to discuss the details of wiring
and so-forth we can do that too. if you're handy with a soldering iron
you might consider building up a solid state circuit to do this while
using the stock cv preamp.

brad

    -----------

what i did on my summer vacation (or how i came by my b3).

dan, the piano player i worked with, (i played saxes), called me and
said "tammy found a b3 at the salvation army and i bought it and a
leslie for $100". he already had an m3 he bought for $35 from the
salvation army. dan lived in a 2nd floor condo and relied upon the
good graces of his fellow musician friends to store all of his
hammonds. bill, the guitar player was storing the m3, and i was
selected to store what turned out to be a bv and 21h. both had come
from a boy's ranch down in ft pierce, fl, where they had resided for
many years unplayed and gathering dust, insects, and graffiti.

into my living room, and beneath the cool gaze of my wife, hands
akimbo, came a factory finished black b3 shaped hammond with pedals
and no bench. also across the threshold came a brown 122 shaped leslie
with a single upper vent on the rotor. dan was giddy and acting silly.

a quick look at and in the back of the units revealed their true
identities:

brad: "hey dan, this is a bv and a 21h - not a b3 and 122. it's got no
percussion".

dan: "oh. okay. whatever."

in the process of getting the bv working it was discovered that the
vibrato didn't work. the scanner and ac motor were removed. the
scanner was disassembled and a frozen bearing was found in an enclosed
and riveted assembly internal to the scanner. the rivets were removed,
the bearing freed, and new rivets installed. dan was happy. of course
he only played it when he came over to my house, which turned out to
be not that often.

after a month or so dan said, "hey! can you put the m3's percussion in
this thing?"

brad the impusive-engineer-with-obviously-too-much-spare-time
responded,  "oh sure. that ought to be a pizza cake".

with that simple utterance began the conversion of the bv to a b3.

the first act one must perform in a project of this type is to destroy
something. we chose the destruction of a pefectly functioning and
wonderful m3, from which we salvaged:

  1) the percussion tablet assembly - same part # as b3's.
  2) m3 input transformer - not same part # as b3's.
  3) m3's preamp.
  4) drawbars "who knows - maybe we can use 'em" (not)

that's it. the rest of the m3 was left behind to be hauled away like a
stripped car on the curb of a brooklyn street, the empty hulk resting
on milk crates sans doors, engine and hood - the detritus of a b3
conversion project.

    -----------

the goals of the modification were:
  1) install the percussion switch tablet in the drawbar base in the
     correct location.
  2) install the m3 input transformer
  3) split the drawbars so dan could have percussion on one manual
     only, (of course he also gets vibrato on one manual only...)
  4) install m3 preamp with 20 watt dummy load and provide 1/4" output
     jack. 
  5) wail out mightily ala jimmy smith et al.


here's what was done for the conversion:

  1) remove bv preamp
  2) remove bv drawbars
  3) remove bv input xfmr.
  4) install m3 perc. switch.
  5) install m3 input xfmr.
  6) install m3 preamp w/dummy load.
  7) open drawbars, cut bus bars between upper and pedal drawbars. add
     ribbon cable to new upper drawbar busbar set. the ribbon cable
     was routed inside the busbar housing and epoxied to the top, but
     they could have come out the end ala b3 probably more easily.
  8) saw preset bars in half to separate the manuals.
  9) convert leslie to 142 type using 2-speed motors, put in 50w tube
     amp, new drivers, xover.

the whole thing was wired back together and lo and behold it worked -
after a fashion. remember, this thing was 40 to 45 years old and the
old wax and paper capacitors were in less than fabulous condition. it
had percussion, and it had vibrato, though the vibrato/chorus never
really worked as advertised - the bv vibrato line and scanner is
substantially different from the later models. as i recall the chorus
switch - up on the console on the bv - was very hi-z and buzzed loudly
when touched. the whole thing was rather noisy. dan was thrilled
though.

my wife was pleased to get her living room back the day dan's friends
came to move the b? into a local jazz club. dan was the house piano
player for about a year. it stayed in the back room of this club for
two years or so, covered up and  unplayed.

dan, by this time, had found a set of real a-100 drawbars. he didn't
like the notchy ones cuz he couldn't wang on the drawbars like the
real guys do while he was holding a chord, so we changed those. of
course this had no effect on the noise problem. dan moved it to a bass
player's garage. it sat there for a year with garden tools and
christmas ornaments stacked on it. somewhere along the way the music
stand got lost.

dan and i got a gig playing on rory pastorius' (jaco's bro) ill-fated
cd (nuther story) that was recorded at a local studio. dan moved the
organ and leslie to this teeny studio, set up in the lobby. there were
musicians in every available space. i played in a closet. in the
process of setting up the b? dan noticed he couldn't put his m1 on
top. the pesky flip top was getting in the way. (the music stand was
long since lost). so dan didn't remove all those screws in the piano
hinge to take the top off, no, he just bashed and pounded and ripped
the vertical part of the flip top off with the palm of his hand or
something. after the gig, we left the studio, never to return for
another session while the b? stayed behind for 6 months or so in the
lobby.

next, he moved it to his future ex-girlfriend's house. the back panel
thumb screws had gotten lost somewhere during the studio stay. it
stayed there for a year or so until i bought it and the leslie from
him in march '94. in all the time he owned it, dan actually had played
it very little.

    -----------

i told my wife i intended to strip the case and rebuild the guts as a
b-3. she was surprisingly non-pessimistic about the project. on the
other hand, maybe she just saw it as yet another of my future
unfinished projects.

i got her involved straight away. "it'll be something we can do
together". plus, i would get to foist off some of the blame on her
when the project ended up unfinished or didn't work at all. it's
always a good policy to make as many people culpable as possible on
projects of this magnitude.

she left the project all to me after we removed the guts and moved the
case onto the back porch. i stripped and stripped and
stripped. underneath all of that black enamel was beautifully
preserved walnut. after some wood repair, (i had to reglue the flip
top), and a staining and finishing with tung oil, it looks better than
i had hoped. i like it so much that i think she's going to bury me in
it.

    -----------

for the new conversion i obtained:

  - b3 input xfmr.
  - b3 preamp (thanks goff people).
  - new capacitors for tone generator.
  - new capactors to rewire vibrato line xfmr like a c2g.
  - b3 vibrato switch assembly.
    
the vibrato line was rewired to conform to a c2g style. this is the
large line box but works with selectable vibrato and the c2 preamp,
schematically very similar to b3 normal and vibrato sections.

the chorus/vibrato switch was removed and disassembled. the bv's
chorus/vibrato switch is a shaft driven affair with twenty four or so
cam-driven contacts arranged in three groups of eight. in the bv the
switch's six positions correspond to v1/c1, off, v2/c2, off, v3/c3,
off. in the b3 it's c1, v1, c2, v2, c3, v3. i had to grind the cams in
the bv's switch to make it hold a group of eight contacts closed for
two adjacent rotational positions as the b3's does. the cams are some
kind of plastic material and grind easily with 150 grit paper.

a micro switch was installed under the "b" upper manual preset key ala
b3.

the tone generator cap's were obtained by calling a capacitor maker
upon recommendation of one of our component engineers. i was going to
buy them but when the sales rep found out they were for a b3 rebuild
project he gave them to me as samples. it turns out he was a
rock-n-roller in the 60's. the cap's are all 1% tolerance  at the
value in the schematic. this is said to be the way *not* to rebuild
tone generators and when and if i do it again i'll match them
individually to each output. as it turns out, i'm pleased enough with
the results that i probably won't bother rebuilding this one.

    -----------

i fired the whole thing up and voila - it was music to both my eyes
and ears. that and a pristine 145 comprise the center piece of the
living room. i have about $1300 in the b3 and the converted leslie and
lots of hours of work. it's been the most rewarding project i've ever
done and has given me new passion for my music, the real reason i got
involved with the project anyway. (plus, i get to spout off on the
hammond list as if i know what i'm talking about.)

i use the rebuilt 21h leslie for gigs with a micro-b. it's okay but,
after playing the b3 into the 145 w/goff driver, it's missing
something somehow. hmmm, all i'll have to do to it is take out that
driver and...

brad baker
bpb@mlb.cca.rockwell.com