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

[flyweed]

Hey guys

Ok, so we have some (32) 6 inche altman and LE fresnels, and I can NEVER keep a lamp working in them for more than say 2-3 shows. It seems that the bases that make contact with the contacts in the ceramic base "eat away" at the contacts on the lamp and they "die" a quick death.

I'd like my fresnel lamps (BTN and BTL's) to last at least more than 2 or 3 events, as they are pricey.

Anyone have any "fixes" or tricks to get these things to have better contact and last longer?

Thanks

 

[gafftapegreenia]

Switch to a Fresnel that doesn't use the medium prefocus socket. The current replacement sockets have a cup shaped contact that does not play nice with the current generation of lamps.


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[kicknargel]

Do some CB searching - I recall at least one lengthy thread about replacing and/or modifying sockets on 6-inch fresnels.

At the very least, replace the sockets (and the lamps at the same time), as corrosion is infectious.

 

[flyweed]

I am actually thinking of throwing the damn things away...and purchasing a few dozen ETC Parnels.

Anyone want to buy some 6 inch fresnels for CHEAP!!! LOL


So I guess my main question is WHY does this happen? How does this "corrosion" happen? Is this cause from arcing, or heat, or ????

 

[kicknargel]

That's an even better plan. And no, I don't.

It's caused by arcing. The little spring-loaded contact in the socket can get weak, and anyway as gafftapegrennia said, the two parts are designed such that the point of contact is really small. Hey, C- engineering students need jobs, too.

 

[JohnD]

Something I recently noticed when browsing the BMI supply catalog was this:

http://shop.bmisupply.com/ProductDetail/402003HPL

 

[flyweed]

NICE...I like that retrofit kit!!

I have full welding capabilities in my scene shop.... could we put a "spot" of weld onto the current "contact" in the base to enlarge it and tighten the gap up between lamp and base contact?? It seems like that would be pretty easy.

 

[Colin]

The mentioned HPL kit is very worth it in my opinion. I swapped a system's worth last year and might do more. Cleaned and painted the bodies at the same time, added strain reliefs. My 6" fresnels are a mix of various generations going back to some ancient Century fixtures and just a few Altmans. Maybe for that reason or maybe just due to the slightly wacky construction of the whole retrofit kit, it wasn't quite as smooth a swap as one might hope, but with a little tinkering they all went together. The spot/flood sled (is that an official term?) doesn't slide nearly as easily as the original equipment, and I think has less available travel than before, but since I usually keep them near center of travel anyway it doesn't bother me.

A cheaper solution, especially if you have a large stock of medium prefocus lamps to burn through before making the switch, is to get a Dremel and a couple different shaped grinding stones and clean up the surface of the contact in each cruddy lamp base. Several people on CB do this, including me, and you'll find a thread or two if you search. Also flood the spring area of the contact with contact cleaner and move it around until the spring works again, since those often start to stick too far down making the arcing worse too. You can clean up the "BB" on the bottom of a lamp with some fine sandpaper too, but if it is too far gone you're better off throwing it out because it will just make the freshly surfaced socket arc and heat up faster. The more you re-surface, the shorter they last before needing it again, and eventually you remove too much material to put them back in service, so it still isn't ideal. If you have the money now to retrofit full systems at once, and don't have lots of MPF lamps that would be wasted, jump right to the HPL kit.

I know I'm not the only one who has a deep resentment of PARNel inventories. Not ETC's finest achievement. The beam and gel life stinks in comparison to a true fresnel, and the focusing mechanisms are prone to failure. Stick with the real thing, or get S4 PARs if you want new fixtures.

 

[Scenemaster60]

I have been doing what Colin suggests on several inventories that I maintain here in the Twin Cities. It's a real PITA. I have played with the HPL kit and I personally don't like how the beam looks. The fact that the S4 lamp filaments are not in a tight plane like the BTL/BTN/... lamps causes the field to be splotchy, especially at flood.

Now, as I sit here typing this it occurs to me that one thing I might try is putting a late-generation med bipin lamp like a GLA into one of the kits. That filament design is much closer in geometry to a BTL/BTN filament and the height of the filament assembly is ALMOST identical. I realize that the bases of those lamps are smaller and that there would be a much greater risk of lamps working their way loose since it would be only the tension of the contact pins holding them in. Experiments will be performed and I will get back to you all!

 

[kicknargel]

Source Four does also make a traditional fresnel. I've never seen one in the wild.

I've heard ghost stories of someone adding a dab of solder to the BB on a fresnel lamp in a pinch. I'm sure it violates UL listings, and is bad for all sorts of reasons.

 

[BillConnerFASTC]

I never found the parnell to have the spot to focus range and nice soft edges that a 6" fresnels do. But YMMV.

 

[techieman33]

I never found the parnell to have the spot to focus range and nice soft edges that a 6" fresnels do. But YMMV.

Agreed, the parnels are ok, but the beam can be pretty uneven at the wider focus range. There is also usually a big dark spot in the middle.

 

[Les]

Sounds like a good time to invest in the Altman Pegasus!

...or buy the HPL retrofit kit. I would try either of those two options before dropping $300 each on Parnels or S4 Fresnels.

There is a bit of history with certain batches of med. prefocus sockets going bad. I have never seen it in any inventories I've ever maintained, but it has affected several people here. Sadly, it may have only started with a few bad sockets and fanned out from there. Your sockets are now damaged to the point where they will ruin any lamp you put in, and attempting to use that lamp in another fixture will spread the issue on and on... Which is why it is said to spread like a virus.

I would not weld, solder, or modify the sockets aside from maybe re-surfacing with an Emery cloth. I'd upgrade the socket assembly or upgrade the fixtures completely.

 

[MikeJ]

I never found the parnell to have the spot to focus range and nice soft edges that a 6" fresnels do. But YMMV.

Yeah, the parnel is a big flop. I have never seen the S4 fresnel though.

I am actually thinking of throwing the damn things away...and purchasing a few dozen ETC Parnels.

If you are considering replacing fixtures, look at the Ovation LED Fresnel from Chauvet.

 

[techieman33]

Yeah, the parnel is a big flop. I have never seen the S4 fresnel though.

If you are considering replacing fixtures, look at the Ovation LED Fresnel from Chauvet.

I haven't seen one of the Chauvet units in person, but I'm leery of any white only LED fixture for a theatrical application. Weird things tend to happen when you put a piece of gel in front of them.

 

[MikeJ]

I haven't seen one of the Chauvet units in person, but I'm leery of any white only LED fixture for a theatrical application. Weird things tend to happen when you put a piece of gel in front of them.

I have used them in person, and actually, I have not ever put a deep color in from of them,. I was mostly concerned with using them for corporate, and video lighting. So pretty much white light, maybe with CTB.
When I get some next time I'll try to find time to test them with a variety of colors.

I hope to see the new color changing Leko from Chauvet soon, so I have a suspicion that a color changing Fresnel is not too far away. If I find time Maybe Ill do a quick comparison of various fixtures; LED and conventional from different brands.

 

[JonathanHarpur]

To bring it back to bad sockets... Short of replacing your sockets, you can try removing any carbon buildup (from previous lamps' arcing) in the old sockets with a bit of abrasive - emery cloth might work for you - and you might also consider trying a conductive paste (make sure it's temperature-appropriate!) to aid in minimizing future lamp/socket arcing as well.

If the socket is difficult or impossible to replace because it's not made any more (I'm looking at you, Strand), and you're out of other options, tip tinner does an okay-but-far-from-ideal job at repairing some of the damage.

Don't forget to factor in your time in the effort/cost/value evaluation process. It's possible it's better overall to write off bad fixtures than to keep throwing money at your lamp supplier. My home venue recently did just that (well, likely except for the "factoring in my time" bit), and I got some much nicer 7" Selecon Ramas to replace the relatively young Strand Fresnelites I used to have. Still have BTRs in them, though, but these seem to be better sockets - for now.

 

[derekleffew]

Now, as I sit here typing this it occurs to me that one thing I might try is putting a late-generation med bipin lamp like a GLA into one of the kits. That filament design is much closer in geometry to a BTL/BTN filament and the height of the filament assembly is ALMOST identical.

At first I didn't believe you, but after investigating, it just might work. My skepticism may have come from poor results with EHG/EHD lamped Fresnels. If the socket can support a GLC, and if the retrofit relector is not tailored specifically to the unique HPL filament layout, it's a great idea. Let us know how/if it works.

 

[Scenemaster60]

Derek, the reflectors in the retrofit kit at exactly the same as the standard Altman reflector. It would appear that whomever is the third-party manufacturer is for these kits buys the reflector assemblies from Altman or their supplier and then installs their machined "thing-a-ma-jig" which contains a standard HPL socket. I think that is why the light from the retrofits with an HPL lamp is not as even. I suspect it would be possible to design a reflector that was able to produce an even field from an HPL lamp in a fresnel. I have not had the opportunity to work with a genuine ETC fresnel. I would suspect, however, that they created a reflector designed specifically for the HPL lamp and that the field it more even.

The trick to usin

 

[JonathanHarpur]

...If the socket can support a GLC, and if the retrofit relector is not tailored specifically to the unique HPL filament layout, it's a great idea...
View attachment 12706

You may also want to try out the FLK [300hrs] (or FLK/X [2000hrs]) lamp - it's almost a half-step from both the HPL and FEL lamps - simple, central single coil filament, but no heatsink base. 575W, with similar output to HPL 575s. If you need a bit more punch, look at the 750W EHF. Depending on your supplier, these can be cheaper to equip than the HPLs, although from what I can tell that small margin is shrinking.