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Author
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Topic: Technical help on an old 16mm Thomson Houston Movie projector
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Jeff Taylor
Jedi Master Film Handler
Posts: 601
From: Chatham, NJ/East Hampton, NY
Registered: Apr 2000
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posted 09-11-2013 05:08 PM
I'm not familiar with the machine, so this is just general info. As far as oil is concerned, most any general machine oil should be better than none, but keep in mind that it may have to work its way into long neglected oiling pads. Do you see any cotton pads or the like? Give it some time. As far as the exciter is concerned, (1) do a continuity check on the exciter lamp, (2) if that proves ok your problem may be with the amp. That vintage machine typically used a tube-driven oscillator circuit to power the exciter. I don't know European tube numbers, but in the US you'd typically have 3 of one type tube (6V6/6L6, etc). Two would be push-pull output tubes, and the third would be the driver oscillator for the exciter supply. Try swapping those tubes around. Finally, (3) given the age of that machine I'll almost guarantee the caps (capacitors) are bad, and resistors may have drifted so far as to be way out of value. Those components should have markings on them with their electrical values (resistors require a commonly available color stripe card). Have I totally confused you? Post more info, and I'll try to help more, or check with the following 16mm enthusiast website: 16mmfilmtalk(dot)com. Good luck.
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Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
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posted 09-12-2013 11:32 AM
Info on British Thomson-Houston, in case you're interested!
As you'll see, making projectors was only a very minor part of what they did: here are some BTH objects in the Science Museum, including a fridge and bits from a gas turbine motor!
As you'll gather, the company is long deceased. Several changes of ownership and takeover later (AEI - GEC - BAe Systems - Marconi - split into Ericsson and Telent, with some parts of the operation sold to Huawei and others wound up), it's anyone's guess whether any BTH archives survive and where they'd be. So I suspect that your chances of finding a service manual or other technical documentation for this machine are very slim.
So Jeff's suggestions are the way to go. I know this sounds pretty obvious, but I take it that you've checked the exciter lamp itself (i.e. looked at the filament and then continuity tested the bulb if it looks OK)? Assuming that's OK, checking the vacuum tubes (known as thermionic valves in British English), replacing all capacitors and resistors on spec and checking all the electronic components for dried out and failed solder joints is the way to go.
Also, when the machine was made, the British mains electricity supply was 240 volts, not the 230 it is throughout the European Union now, but I wouldn't have thought that would make enough of a difference to cause a power supply fault. The function of the transformer/power supply unit probably does want checking on a machine that old anyway, though.
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Jeff Taylor
Jedi Master Film Handler
Posts: 601
From: Chatham, NJ/East Hampton, NY
Registered: Apr 2000
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posted 09-13-2013 08:38 AM
Just one final post on this topic. I have numerous 16mm projectors, but use two EIKI xenons primarily. Just for sentimental reasons I bought an RCA 416 this year (I have a lot of home movies at 16 fps and have owned perhaps 20 RCA 400's over the years). I bought it from a guy who knew nothing about the machines, but got it from a church (low hours). The spring belts were shot, the idlers were frozen, and the power cord was dried out--20 minutes work. After determining that it worked very well I gave it to my son who designs and builds tube (valve) guitar amps which he sells for $2000 and up, and he went through the simple tube amp on the machine. He found one 6973 output tube that tested suspect and replaced them both (the Russians make them now), but ALL the caps checked out within range after 45 years. I know it's wise to suspect all old caps, but this is one time it wasn't warranted. Perhaps the fact that I brought it up with a variac and hopefully reformed the caps paid off, or maybe I was lucky. Who knows.
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Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
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posted 09-13-2013 02:26 PM
About a decade ago, a close friend bought a 1935 His Master's Voice radiogram in a house clearance sale: 78rpm turntable and LW/MW radio only. She really wanted it as a piece of furniture, not a working entertainment device - it was a solid oak, beautifully polished cabinet and needed only minor work by a French polisher to look like new. Her original plan was to gut all the electronics out of it and use it as a drinks cabinet, but before doing so she asked me to investigate if it was still viable for use as a radio, at least.
My first instinct was to replace all the high voltage wiring just as a step one, before trying to do anything else whatsoever. But, just as an experiment, I thought, "I wonder if we just plug this thing in, if it'll still work after 70 years, 50 of which were in storage and unused?"
The mains plug was an old round pin one, and so I had to replace that; and as an added precaution I connected it through a RCD (GFCI). So I connected it, pressed the reset button on the RCD, and, surprise no. 1 - it didn't trip! I then switched it on ... still no trip. Two or three minutes later the valves had warmed up and were glowing nicely. A little twiddling with the tuning knob later, and bugger me with a soldering iron, I was listening to Radio One! It was really strange hearing U2 blaring out of an object that looked like it belonged on the set of The Thirty-Nine Steps or in Hercule Poirot's apartment.
The turntable bearing had seized, but it only took about a couple of hours of disassembling, cleaning and lubricating before I had it playing records as well.
We eventually found a specialist restorer who, for £400, replaced all the internal wiring, the caps and valves, cleaned everything up and added an aux input to enable a DAB/FM radio and a CD player to be connected. The thing has been a party piece and a talking point in my friend's house ever since, has been in daily use and she's even started to collect shellac. There are several places online that sell replacement steel styli for the enormous ceramic pickup cartridge, which I'd never have guessed.
But things were clearly built to last in those days. I was astonished that after seven decades and probably with no maintenance whatsoever during that time, it worked almost as well as on the day it was bought.
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