Add A Tenth Set Of Contacts

MikeFulk in a post to TheHammondForum has pointed out:

On M-100's and L-100's the actuators on both manuals have ten slots instead of nine. There are no contacts or busbar for the 10th slot(s), but think of the things one might do, e.g.:

• Key just about anything

  • MIDI (non-velocity-sensitive)
  • percussion keying

• add separate 13 contacts and short busbar so that pedals may be on manuals, add sub-third or sub-fundamental harmonic on lower manual... also, on lower manual add both sub-third and sub-fund by rewiring 10th and twelfth harmonics.

Apparently not all M-100's lend themselves to decibusification. An anonymous editor adds~:

  L-100s may have 10 slots in the actuators, 10 slots for busbars and 10 slots for contacts, but
  not _all_ M-100s have this "feature".

  In M-100s, there may be ten slots in the actuators.
  There may also be a tenth slot for a busbar but no insulated guide for that slot.
  *And* the contact boards have only *nine* slots.
  Based on my experience with an M-101 and an M-111.

TopicModification

I am the anonymous editor who added the above comment.

I am Alan P. ?DuBois and I own and work with Hammonds.

I am editing this post to reflect my latest discoveries regarding L & M100 manual chassis that will accomodate 10 busbars.

The L133 manual chassis I originally spoke of is of different design than any other Hammond chassis I have seen. The actuators, contact boards and terminal strip are ALL made of plastic. Hammond chassis usually have bakelite boards, etc., - interesting....

NONE of the M100 chassis I have worked with will accomodate 10 busbar contacts. That is, _until recently!_

I opened both an M103 and an L111 recently and they _both_ have room for a tenth busbar _and_ room for contacts for the tenth busbar, if installed. These chassis are the same as the L133 I described above. All plastic guts.

I checked my history working with these spinets and found that 1964 and earlier L & M100s used the bakelite boards and would not accomodate 10 busbars. I have _not_ been into a 1965 vintage spinet. And, the last two models I opened up are 1966 vintage.

So, it was obviously a production change in 1966 (for sure) and possibly 1965, where Hammond added this "feature."

To find out if your L or M100 has such a chassis, from frontside, remove the metal L-shaped cover from the lower manual chassis assembly (two screws at each end). If the terminal contacts are mounted to a black, plastic board (as shown below), chances are you have one of these 10-busbar chassis.

Note the "square" busbars used in this chassis

I added a tenth busbar as shown in this photo.

Thanx, Alan

   Great write-up Alan!  Thank you for contributing to the wiki. -- JeffDairiki