Odd Electro Controls Fresnel Design


Well-Known Member
I got called to a small town high school to troubleshoot some lighting issues in their auditorium because they couldn't get several stage lighting fixtures to work.
It was an analog Electro Controls system from the 1970's that we did maintenance on 8 years ago with all tungsten fixtures.
Found the usual problems.... no lamp in fixture, good lamp and power but no light, and no power to 4 circuits (Electro Controls aluminum raceways and Quad dimmer rack).
Resolved most of the issues which mainly involved numerous bad lamp sockets and one dead SSR in a dimmer module, but still had 3 dead circuits after testing the dimmers involved.
Either bad raceway outlets or wiring between dimmer rack and raceway (which were dead hung). Will let an electrician sort that out.

Anyway, the Electro Controls fresnels were something I had not seen before as they used an EHG 750 watt bi-pin lamp with a very small non-polished reflector as shown in the photos.
They seemed to work pretty well for what they were used for but replacing the lamp was really difficult because it was sitting halfway in the slotted reflector!
A neat design touch was that the lamp sled along with power lead/wiring and complete screw focus mechanism were all contained in a "tray" that was held on to the fixture body by four screws.
Take the screws out and the "tray" can be separated from the body shell.

EC fresnel lamp 1.JPGEC fresnel side.JPGEC fresnel side rear.JPG
Hmm, that's a fixture I don't have in the museum yet.
You didn't mention the condition of the lamp socets themselves, or analization of the pins on the removed lamps at all as per indication of what was replaced - also an indication of the socket. Eight years is a long time for a lamp socket being good if in various use, assuming the socket was changed last time serviced?
You traced house wiring issues which are uncommon, but don't mention the TP-22 lamp sockets in use which have their own drama. Back to the "put a perfectly good lamp into a bad socket" concept well posted about. Sorry in asking, but do you need to go back for free in troubleshooting that part of of the problem in some how... "I know what the problem is" and it's going to cost you in fixing it.

I had to go out to a drape hang earlier in the past year in sucking it up and adjusting the drapes we installed. I sucked it up and worked with the TD in a PC way that yep we screwed up the install in a way that they would still trust us. And I provided free service in other things not fixed. Part of the thing in making it right. Again, I did not see anything about bad lamp sockets in your post, and do not infer about your fixture inspection, but do post the question of some of the problems to ensure and correct for your origional service call which might indicate lamp socket problems.

Users who are viewing this thread