Strosacker Progress Report #2

Oops, I blinked and a month slipped by already. And it's been a busy one...

First, the University's grand plans have had to be scaled back a bit--the bids for the Strosacker project came back a wee bit higher than expected, so the electrical/lighting overhaul, fire alarm, sprinkler system, and associated small bits of carpentry have all been deferred until next (?) year. But the work on the screen, chalkboard, and related front-wall stuff is all going full steam ahead.

Second, we've finished the initial mechanical and wiring work for the Dolby Digital and upgraded analog sound. Now we can get started on the fiendishly difficult parts: getting the optics lined up exactly right (requires an oscilloscope, a PC, a fistful of test films, assorted wrenches, and an extensive vocabulary of 4-letter words), and hacking the CP-200 to Do The Right Thing when the digital processor tries to revert to analog in a format that the CP-200 is too old to grok.

More details, with pictures, below.

7 weeks down, 5 left to go. The blow-by-blow version:

Week 1, 5/19/05

Removed the old screen material so contractors can see behind & below to prepare their plans & bids.

Week 2, 5/26/05

Take detailed measurements of the old screen frame, and the obstacles on the wall (mostly counterweight tracks for the panel door & chalkboard) that the new frame must work around. Started disassembly of the old optical sound head in #1 projector. Discovered that the bearings for the sound drum shaft are toast (need to replace 2 bearings in each machine). Mounted Dolby DA-20 digital processor in sound rack.

Week 3, 6/2/05

Ordered new bearings. Dissasembled #2 optical sound head, 2 more bearings hit the junk heap (partly because removing the old ones requires too much force, partly because they were a bit crunchy even before being whacked with a pointy object).

Week 4, 6/9/05

Removed the main speakers from the wall behind the screen to get out of the way of the destruction that will be happening soon. Ran power wires for LEDs, tested LEDs (had to determine their polarity by trial & error--per the installation manual. Is it really that hard to do at the factory? Ran digital signal wire (heavy video-type cable) and new analog signal wires. Re-purposed one old signal wire for analog pre-amp power, used the 2nd old signal wire to pull new wires through flex conduit to the raceway.

Week 5, 6/16/05

Old subwoofer removed from the wall below the screen. Bearings have arrived, we installed first parts of new sound heads: damping rollers, sound drum & flywheel, LED assembly.

Week 6, 6/23/05

We took this week off (which I came to regret, but that tail of woe will have to wait for another blog entry)

Week 7, 6/30/05

Finished installing the digital/analog readers in the projectors; mostly, this invoved making the final LED power connections and running the analog signal & power wires through the back side of the machine to the compartment where the analog reader/pre-amp is now located.

Lost a full hour to looking for a plastic thingy that fell off the end of a wire (improperly attached the first time) and was needed to plug in to the analog LED power connector on the #1 machine.

Week 8, 7/7/05

Knox's First Corollary to Murphy's Law: any operation that involves opening up the wiring raceways will take 1-2 hours longer than expected.

We finished the DA-20 motor sense wiring (one relay per projector, each closes when its associated motor is switched on; the DA-20 uses this to tell when it should be looking for potentially valid digital sound data on each of its inputs). There were also a few solder connections between various DA-20 sense/control wires and the back of the CP-200 to be taken care of.


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And what exactly is it that you were trying to accomplish here ? Is that some kind of movie projector ?

Posted by gareth on April 6, 2007 08:47 PM

Wow, that's a piece of history. Impressive machine, and kudos to you for keeping it alive! Jeremy

Posted by Jeremy on July 10, 2013 06:09 AM

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