Theater Organ TechTalk -


A Series of Articles on Theater Organ technology - how things were (and are) done - and why.


Robert Morton Wiring System.


During the early years of motion pictures - particularly during the silent movie era - theater organs were being built and installed by the hundreds all over the United States. Some estimates claim as many as 5000 organs were installed between 1918 and 1930, with overall totals reaching more than 10,000 installed theater organs at the peak of the movie palace era. As a leading builder of theater organs, Robert Morton had developed a modular approach for it's "standard" or "basic" instrument - resulting in an almost assembly line like method building organs. The basic console (two manual) was self-contained (i.e. it contained all of the relays required for selecting and contolling the pipes). If a theater was to have console with three manuals - there was a "kit" of sorts - that added the manual, stop rail, etc. - while the relay for that manual was placed (usually) in one of the chambers. This allowed Robert Morton to completely build, wire, assemble and test an organ at it's Van Nuys California factory- then disassemble it - pack the modules in a truck which delivered them to a theater. Once there - the modules were unpacked and installed - the factory made cables run between the console and the chambers - hooked up and the organ was playable. Of course tuning, voicing, etc. still had to be done on site - but still the time to install an organ built this way was remarkably short. One issue Robert Morton had to solve was the cabling between the console and the chambers. A small organ can easily run 5 to 6 hundred wires - A modest sized organ can run into the thousands. Can you imaging trying hook up several hundred individual wires - figure out where each one was supposed to go - and keep in mind - these had to be connected at BOTH ends - twice as many connections as wires? Making the potential for disaster even greater was the fact that Robert Morton tended to use one color of wire for most cables. Obviously - some solution to this had to be found - or days could be lost just trying to "wring out" the wiring. The solution Robert Morton developed was a standard system of interconnects which are pre-wired at the factory - tested then shipped along with the rest of the organ.

One of the key elements to thier solution was the way Robert Morton built their relays. There is a article on Robert Morton relays here: Theater Organ Tech: Robert Morton Relays.

Robert Morton Relays were made using custom jigs that allowed many parts to be made very quickly - yet insure that contact spacing and other dimension were uniform - and for similar parts - interchageable. The unifority of contact spacing was a key that Robert Morton engineers expoited in coming up with their interconnect solution. The fixed contacts of the relays in the console are the "termination" end of the cable to the chamber(s). A wooden "spreader" was made that has two functions: one is to provide an anchor / locator for each wire, and 2) provide a connection pin that serves as the "bridge" between the outgoing cable wires - and the fixed contacts of the relays. For connections that do not terminate at a relay (such as swell shade contacts, etc.) a pin header is installed in the console that takes the place of the relay fixed contacts - and accepts the same "spreader" type connection.



This is the top of the Bourdon relay in the Temple Theater's Robert Morton console. This is the largest (width wise) relay in the console- with 97 fixed contacts. There are six additional "sections" below this one. Here the spreader has been un-soldered and partially removed. One can clearly see how the spreaders facilitate getting the right wire to the right contact. You can learn more about these relays in the next Theater Organ Tech article.

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