Anatomy of a WurliTzer Theatre Pipe Organ
The Switchstack Action Chest must be the most rebuilder unfriendly design that WurliTzer produced.
Fortunately they only need a rebuild every 70 years or so, so there is no reason to to take the easy
way out and dump it and replace it with an electronic substitute.
Once all the Switch pull wires have been disconnected from the arms behind the switches the wires can be
turned down flat on top of the chest. It is then possible to remove the screws holding the chest to the
legs/frame of the switchstack and then slide the chest out. With the chest on the bench it is much easier
to remove the wires from the loops that connect them to the pneumatics, usually by opening the loops
The side covers are easily removed and then the bottom board can be removed. This is unusual in that the
sides screw to the bottom board and must be removed to allow the bottom board to be removed. Other chests
that have removable sides tend to have bottom board permanently attached to the ends, and top, as part of
the main frame of the chest, like the Traps Chest.
The top board cannot be removed without disconnecting the wires that run through the top of the chest
from the pneumatics. Getting into the small gap
between the pneumatics and the top board to open the
loops on the top of the pneumatics and wriggle the join apart is not easy. It is much easier to knock
the pneumatics of their mounting board which allows the top board to be removed with the pneumatics
hanging off it. This then allows the pneumatics and wires to be seperated more easily. Unfortunately
at some time someone had added two extra actions to the Opus 2027 Switchstack. That would not have been
a problem if the pneumatics had been mounted using the usual glues with a gasket under the pneumatic.
With PVC-E glue holding the pneumatics directly to the base board there was no way anyone can remove them
without doing serious damage. As I was going to releather the pneumatics anyway it did not matter that
I just cut those in half so only the top halves were removed with the top board.
Wtith to top board on the bench it is relatively easy to move the wires and pneumatics around so that
the loop on the top of the pneumatics can be open a little and the links can be seperated from the pneumatics.
The link wires can then be removed from the top board by removing the batton strips that hold the
strip through which the wires run. There is no seal between the wires and the brass strip, just a close
fitting hole for the wires to run through. Once the strip is free
the wires, with the loop on the end, should slide out through the hole in the top of the chest.
The pneumatic mounting board in the middle of the chest fits into a slot in each end of the chest and looks
like it should slide apart once the screws are removed. It doesn't. These parts are glued together as well
as screwed. There was still the problem of the pneumatics that were glued directly to the wood. These were
removed with a plane until almost gone and then finished off by sanding to remove the glue.
Fortunately the chest was fully drilled for the maximum number of actions and the excess places sealed
with cover plates.
To add the required extra switches for the Chrys it was only necessary to trim the
appropriate covers to reveal all the holes and install the extra magnets, primary pneumatics, valves
and secondary pneumatics when all the original parts were reinstalled in the chest.
Reinstalling all the parts after refurbishment was only a little more difficult that getting them apart
in the first place. One feature of this chest is the amount of gasket leather you use and the number of
holes that need to be punched in it. Holes should not be punched for chest holes that are not going to be
used. The gasket will seal the unused chest holes, along with the cover plates.
Glueing the gaskets to the mounting board for the secondary pneumatics was much more easily done before the
assembly began. The gaskets then provided a clearly visible guide to the location for the pneumatics.
Glueing the pneumatics down has to be done in the limited space provided. A few extra
helpers in the form of clothes pegs and a vernier caliper helped keep things as far out of the way as
possible. I suspect the WurliTzer factory employee with the smallest hands had this job.
This Switchstack specification was small enough that the number of switches rquired left enough space on
the switch panels for all the cable spreaders that connect the main cable from the console to be mounted
below the switches on the switchstack. On larger specifications the switchstack panels would be filled
with switches and the spreaders would be on a seperate panel nearby. The spreaders for the two keyboard
cables which connect to the Relay took up just the right amount of space that was needed for the four extra
switches required for the Chryoglott to be added. Moving the keyboard spreaders elsewhere or replacing them
with plugs would not be a major consession to originality relative to the benefit gained by having the
space for the switches.
Switches are arranged on a switchstack the longest switches, e.g. the 109 note Flute, at the top and the shortest,
e.g. the 18 note Chimes, at the bottom. This is because the lowest switch is operated by the action nearest
the end of the chest, working towards the middle as you move up the switches. Adding switches at the bottom
of the stack meant they should use the outer actions which were previously used by the higher switches.
It would have been easier to ignore the normal pattern and use the added actions near the middle of the chest
to operate the added switches and leave the originals as they were, except for the fact that the added
switches are short so that they do not stretch over to the more central actions. The only practical way
was to move all the original switches towards the middle and keep everything in the order it should be.
Above the new switch locations were the Glock and Xylo switches which were to be moved, at least as far as
the actions were concerned. As they were moving anyway it was possible to make enough space for an extra
Xylophone tab to be used to bypass the reiteration function and convert
to single stroke operation. Although not a standard WurliTzer feature this is currently the preferred
style of use and this method of changing its operation does not effect the original fuctunality while
conforming, as closely as possible, to how it would have been done it it had been done originally.
Moving the switches to new action positions is done by drilling a new hole in the back of each switch for
the pull wire arm and making a new slot in the panel for the arm and
remounting the spring block.
The new switches were then mounted, after they had their new cables
terminated. Although the Chrys is the normal 49 notes the switches that were available were 61 notes.
While it is simple to cut down the switches, as I did for the Xylophone, the space was originally
used for the 61 note keyboard spreaders so keeping the switches at 61 notes was more appropriate.
It does mean that thaose switches could be reassigned to something with 61 notes if required at some
future time, although I do not expect that to happen.
On the other side panel the 8' and 4' Accompaniment Flute Switches were moved up one position, displaceing
the 16' Accomp Bourdon Switch which no one seems to think is very useful anymore, to allow a 2'
Piccolo to be added on the Accomp where there was previously nothing above 4'.
Directly substituting the 16' switch with the 2' switch would have been a little simpler, but the
order would not have been correct. The Bourdon Switch was not
completely removed. It ws placed in the cable box at the side of the Switchstack and could be restored
to originality in minutes.
During the work on the Switchstack panels all switches were removed to allow all the contacts to be cleaned.
The vertical brass common strips on the panels were polished with steel wool and then cleaned with De-oxit and
Pro Gold contact cleaner from CAIG Laboratories. The switch contacts were wiped with the chemical cleaners.
As the switches were remounted the horizontal position was checked to ensure the contacts were all
centralised relative to the common strips behind and adjusted as required with the screws in each end
that also provide the bearings through the mounting blocks.