Anatomy of a WurliTzer Theatre Pipe Organ


Action Chest.

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 a little.

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 thin brass 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.



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