Film-Tech Forum ARCHIVE: bulb contacts frying out in effect projector

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Posted by Jeff Else (Member # 4063) on 02-27-2010, 02:31 AM:

i have a vintage color liquid wheel projector for pre-show entertainment that has been frying contacts on bulbs until they won't light, ala this...

and here is a picture of the socket into which these bulbs are inserted...

why is this happening? my (uneducated) guess is that the socket is bad and making poor conact? if thats the case, does anyone know what kind of socket that is and where it might be found? thanks!

Posted by Bruce McGee (Member # 131) on 02-27-2010, 08:06 AM:

It might help if you give a make, and model number for this projector. From what I see, I can imagine that the actual terminals in that socket are as corroded as the pins on your lamp. I wonder if they can be replaced individually?

Posted by Randy Stankey (Member # 64) on 02-27-2010, 08:56 AM:

Lamps in stage light fixtures will do this if they are not inserted all the way into the socket so they make good contact. Repeated cycles of arcing, heating and cooling will erode the pins on the lamp and the contacts in the socket until they just won't work anymore.

Replace the lamp and repair or replace the socket. You might be able to use sandpaper or a file to clean the contacts but that is usually just a temporary measure. Once they have been damaged, it's usually just a matter of time before they fail completely.

Make sure the new lamp is completely seated into the socket. If there is a clip or a retainer for the lamp, be sure it is in place. Also, do not over size your lamp. A larger (greater wattage) lamp will create more heat and speed the corrosion process. Be sure you are using the correct lamp for the fixture or device. You can sometimes fit a similar but different type of lamp into a fixture but, if it wasn't designed for that device it will cause problems over time. Maybe not today but it will eventually fail.

I'm not sure of the type of lamp or socket. I only remember the ones that I work with all the time. (Altman 360Q and ETC Source-4) If it was one of those I could probably think of a place where you can get replacement sockets. However, I'm sure if you look around, you can get a replacement even if it is not original.

Posted by Bruce Hansen (Member # 281) on 02-27-2010, 11:48 AM:

If the contacts in the socket are corroded, that will cause their to be a resistance between the socket and lamp pins. This resistance will cause heat. See if you can clean the contacts in the socket, or replace it, if you can find a replacement. Try to find the manufacture of the unit (on the web?) and see if you can order the part. If not look up bulb manufactures, some of them sell sockets as well.

Posted by Jeff Else (Member # 4063) on 02-27-2010, 11:54 AM:

all very good advice, thanks! the projector is a rank aldis tutor 2E. the bulb is original spec. the original socket looks pretty bad, trying to clean it may be futile. i will look for a replacement.

Posted by Ron Curran (Member # 3631) on 02-28-2010, 08:38 PM:

This reminds me, I was tidying up our assorted lamp drawer and found a lamp for an old slide projector. No use to us any more but if you need a EHJ 24V 250W 2 pin let me know. Free, except for postage.

Posted by Jeff Else (Member # 4063) on 03-01-2010, 01:04 AM:

thank you, Ron, but we have plenty of bulbs, just need a working socket!

Posted by Gordon McLeod (Member # 33) on 03-01-2010, 01:50 PM:

I would contact your local stage lighting supplier they could probably provide a socket that you could adapt to the mounting in the machine