Conventional Fixtures How do you make your Fresnel lamps last??

[JonathanHarpur]

I would strongly suggest you do not do this. FLK & FEL are CC8 Coils. They will not collect the light or project it at all as well as the C13 (or even C13D) design of the BTL family of lamps. It's apples and oranges. You need to use the right filament for the reflector. Go with GLC/GLA (or GLD/GLE for 750W) if you use the converter for the most apples to apples change. Don't go with FLK/FEL/EHG, etc.

I'd like to clarify that I wasn't suggesting the use of the FLK lamp in fixtures set up for either an HPL- or BTL-type filament, but in one already using FEL or similar lamps. My impression was the light output on an FLK is, if anything, only slightly lower than that of an FEL, while running at a much lower wattage. Apologies for any confusion.

 

[kicknargel]

Pretty sure Ship is advocating resurfacing the sockets. His argument is about method. I believe has outlined it in detail in a past thread, although I'm not having luck finding it at the moment.

 

[Scenemaster60]

Sorry. Ship is 100% right on this one. I used to resurface sockets all the time, and yes, it works SHORT TERM-- but here's the rub-- as you point out in your post above, "I only had to re-do 5 of them...." That's the issue. Every time you scrape a socket "shiny" again, the corrosion you are removing is actually the top layer of metal. You are increasing the gap between the contacts each time you resurface it. You know what leads to arc-out? Poor connection and distance between the electrical contacts. So basically you are making the socket have a worse electrical connection with each "repair". One the socket is corroded, your best bet is to simply buy and install a new socket. Or...you can sand it down, and go through lamp after lamp as you kill them more quickly each time your socket arcs out with ever increasing instances due to the increasing space between the lamp pins and the socket contact.

When I am given a budget for materials and labor, I will always choose a new socket.

However, sometimes you have 20 fresnels you can bring back to life with a dremel and you NEED them for that show. Sadly, this is how theatre works in all too many places.

 

[ship]

Perhaps we are all close on this topic in debate (change them) except nobody has tried how I do it in other than me attesting that it works in techniques presented. Granted not for other than experienced people to do. In general, if you get a mirror finish on a lamp socket, than treat it, it will last - perhaps not years but a long time more as a point. Fair enough though in just replacing it.
Many refining reasons to just replace presented as with not specified with old bases - spring tension of the lamp socket itself - a reason to replace. By the way, check screw tension on all screws on the lamp socket new or old during service calls. During the service calls or lamp changes, you should also be able to detect arching and sping tension issues - like a really weak spring.
Think in point though, there is a large difference between what material is removed from a grinding wheel and a fiber abrasive wheel so amount of surface area should be considered a little moot in point - but a point raised in combination with spring tension of this plate is important for the rest of what Mark says.
Flat based lamps and bases, verses ball tipped lamps and sockets. That’s a great point and an important one to further discuss if up for further debate and study on . Personally I hate the ball tipped lamps as they require either a specific large amount of tension from a flat socket, or a at least medium tension from a cupped socket. Not as bad in working I think a flat base to the hot with a cupped socket.
All about surface area and spring tension in the end from my view point. A largely flat plat against a flat plat with a medium to hard amount of tension superior. This in surface area contact and tension. Take a Mole FAY fixture, large surface area, ball/bead contact to it. 650 watt high output and high heat. Small surface area of contact, but good spring tension. Doesn’t persay arc until the spings become loose, but does corrode at contact. In my further point almost 20 years now in techniques presented for resurfacing lamp sockets, and fairly rare one needs to be changed. Good maintenance but also technique.

 

[Scenemaster60]

Preach, master!
These are the issues that those of us in the non-source4/hpl lamp world deal with EVERY DAY.

 

[ship]

By the way, Mark in replying to this is showing a vendor rep that's out to help others. Osram/Sylvania makes lamp sockets but does not make the lamp socket type in question.