Lamps burning out like crazy!
- Thread starterJoyce Thrift
- Start date
Colin Bishop
ValleyPoint Church AVL Tech
I thought I may have been wrong on that. Thanks for the info.
For the ellipsoidials I am looking at the 750W EHG lamp. How much would that hurt output (3/4ths of the FELs output?) and I assume due to its 2,000 hr estimated life it will last significantly longer which will be good for when people accidentally leave them on in the building. Also when the lamps currently die some turn black and bubble, I know I am handing them carefully, could dirty fixtures be part of the cause of this and thus a bigger reason to clean the fixtures? I read it may be...
More like half. 15,400/27,500 = 56%. Rather than the EHG, I'd consider the GLE. Better filament design, 2000 more lumen s, but 1500 hours vs. 2000, and slightly (~$3 per lamp?) more expensive.
It should be noted that almost ALL stage lamps will well exceed their rated life, as not many times do stage lamps run at 100% for long periods. Unless some idiot leaves them burning overnight, or as worklights for long periods, in which case they should be programmed to 90% max in the first place.
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@ship , @DELO72 , /others will correct me if I am wrong, but blackening (or graying/silvering) of T/H lamps is normal end of life, and may be indicative of the halogen cycle not working because the lamp's envelope doesn't get hot enough to prevent tungsten from the filament from being deposited on the on the envelope rather than back on the filament. Counter-intuitively, it may mean the lamp has not been burned bright enough for long enough.
Blackening (or graying/silvering) could also mean a pinch seal failure and oxygen has gotten where the halogen is supposed to be. Again, normal, unless one can prove it's happening prematurely.
Fixture cleaning is good for maintaining optical efficiency, but would have to be ridiculously bad to account for any significant change of lamp life.
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JChenault
Well-Known Member
If the bubble is small and sharply defined it is likely due to the fillament sagging and impacting the quartz glass envelope. If the bubble is big and more rounded it is likely that it was contaminated by someone touching the bul with their fingers. If contamination is what you are seeing get some alcohol whipes from the drugstore and wipe down the glass after you install it.
Ah' but used to brute force with less efficient filaments on this stage. Talking minds eye of needed output over the general intensity - and how did they ever manage to light the stage with 500w incandescent lamps way back when? How did the original Broadway production of West Side Story ever survive - hand out flashlights to the audience so they could see what's going on?
What brand and type of flashlight do you take up to the catwalks with you? Does the newest flashlight really let your job done better, or just light up more?
Why don't every car have HMI lamps in high color temperature and output to personally to see the road and blind the person driving down the road in the opposite direction?
Rated for a FEL lamp, and used to such a lamp, but I doubt you really need to continue to use such a lamp for any stage. Lamp them to say 750w high output, or long life and get the more efficient filaments partially making up for that. But yes,, you do drop in maximum output, in a theater where dimmers are normally used anyway... so the point is... if you need a special with more output, that light gets a FEL say, and it has more output in head room. The rest if perhaps go to GLD or GLE ANSI coded lamps.
Worried about voltage at the fixture, a EHG 750w lamp is still rated for 120v and 2,000 hour lamp life. This as opposed to 300 hours for the FEL. Loose some output on stage for general lighting - normally under dimmers, get some lamp life. GLD/GLC for maximum output and smaller filament better yet but 115v in following the above in seeing what's your actual running voltage.
Another note is perhaps if you need a single light to output X amount of foot candles, perhaps two lights at 575w will provide better blending, control and more output. GLA/GLC are much better in concept for base lighting lamps. Than you have the GLD/GLC for your specials in head room. Smaller filaments, less output, perhaps more fixtures you can hang per circuit in better overall end result.
What brand and type of flashlight do you take up to the catwalks with you? Does the newest flashlight really let your job done better, or just light up more?
Why don't every car have HMI lamps in high color temperature and output to personally to see the road and blind the person driving down the road in the opposite direction?
Rated for a FEL lamp, and used to such a lamp, but I doubt you really need to continue to use such a lamp for any stage. Lamp them to say 750w high output, or long life and get the more efficient filaments partially making up for that. But yes,, you do drop in maximum output, in a theater where dimmers are normally used anyway... so the point is... if you need a special with more output, that light gets a FEL say, and it has more output in head room. The rest if perhaps go to GLD or GLE ANSI coded lamps.
Worried about voltage at the fixture, a EHG 750w lamp is still rated for 120v and 2,000 hour lamp life. This as opposed to 300 hours for the FEL. Loose some output on stage for general lighting - normally under dimmers, get some lamp life. GLD/GLC for maximum output and smaller filament better yet but 115v in following the above in seeing what's your actual running voltage.
Another note is perhaps if you need a single light to output X amount of foot candles, perhaps two lights at 575w will provide better blending, control and more output. GLA/GLC are much better in concept for base lighting lamps. Than you have the GLD/GLC for your specials in head room. Smaller filaments, less output, perhaps more fixtures you can hang per circuit in better overall end result.
Have to go back to the books in a while to study the clear indicators of failure causes. Silver different than dark gray in a filament/globe failure cause. Osram Sylvania has the recognized manual in the industry about halogen lamps. All you need to do is go to the website, pull up say EHG in the search and it will pull up their version of the lamp. Go to documents section below and it will offer a PDF of a free industry recognized and cited manual on all halogen lamps. It's written at a level almost anyone can understand it. Read it a few times but been a few years. At the moment have a few projects in the way before I can re-read.
Used to have a file titled "Backstage Handbook Notes", but it got corrupted with another saved different file. Have to re-send it to home computer from work computer, remember I had a note in it so as to add to a future backstage handbook about fuses which would be by look of the fuse appropriate also in cause of lamp failure.
Lightguy5
Member
I've still got old Lekolites that I use as work/aisle fixtures and have switched all of them to FLK/LL (the 600w replacement for the EHG or FEL, with the lower color temp for longer life).
My last theatre got the same conversion (360Qs), but I had to re-trim all the sockets as I weeded the EHGs out (just a dab of paint showing it had been re-benched for the new filament).
My last theatre got the same conversion (360Qs), but I had to re-trim all the sockets as I weeded the EHGs out (just a dab of paint showing it had been re-benched for the new filament).
rustystuff
Member
To the OP: Have you seen this? http://www.iar.unicamp.br/lab/luz/ld/L%E2mpadas/The%20Great%20Internet%20Light%20Bulb%20Book.pdf
Or, here's some pictures: http://www.donsbulbs.com/cgi-bin/r/t.pl/failures.html
Enter "Halogen Lamp Failure Mode" in ye olde Google search box..... plenty more to be found than the two I listed.
Or, here's some pictures: http://www.donsbulbs.com/cgi-bin/r/t.pl/failures.html
Enter "Halogen Lamp Failure Mode" in ye olde Google search box..... plenty more to be found than the two I listed.
DELO72
Well-Known Member
123 Volts is very much PART of why they are failing early. Can you profile the control board or dimmer racks to "Full at 97%"? This way you'll be compensating for the over-voltage by never running lamps to full voltage, even when the board says it's at "full". It sounds like the sockets are old and need replacing (the fact you need pliers to remove the lamps). That's easily one of the cheaper solutions and should be done anyway with old fixtures. Are the fixtures rated for 1000W? I agree with Les that you'll likely get longer life and be happier if you lamp them with GLE's instead. A combination of things should help:
1) Replace the sockets on your fixtures with the latest TP20XL sockets.
2) Change lamps to 750W 115V/X (long life) GLE lamps
3) Profile your dimmers or lighting console to limit the max output to ~97 percent so when the Board Operator brings a dimmer to full, it is actually only providing ~97% power to it. This will take you down to below 120V, and closer to 115ish so they last longer.
1) Replace the sockets on your fixtures with the latest TP20XL sockets.
2) Change lamps to 750W 115V/X (long life) GLE lamps
3) Profile your dimmers or lighting console to limit the max output to ~97 percent so when the Board Operator brings a dimmer to full, it is actually only providing ~97% power to it. This will take you down to below 120V, and closer to 115ish so they last longer.
steve550
Member
This might seem like a stupid question, and I don't think anyone has asked yet, but are you sure the lamp bases are pointing in the correct direction? Most incandescent filaments are designed to sag primarily in one direction. Any other direction snaps the filament prematurely, causing early failure... I once walked into a brand new high school auditorium back in 1980 where the construction crew or maintenance staff had hung every single fresnel upside down. (No gel frames yet.) Luckily, I caught it before they were used for anything more than a test run.
No stupid questions ever asked! No advice or posting not worth when you think you have something of value to add - this especially but not only when from experience. See Dummy Loadings when it comes to LED lights on stage dimmers. That's a early stage ighting concept - like really early. Read a Ushio mailing today... LED normal lamps are coming out finally without the need for a special dimmer or dummy load.
In the case of Fresnels in the 1980's, assuming incandescent lamps still in use, it would be bad to hang such a light upside down as they were base down to horizontal rated. Normal Halogen lamps are universal angle burn, but would also let the gel frames fall out if hung up-side down. And good catch on your part - maintenance staffs often need checking up on and inspiration so as to become involved instead of 9:5 hindering. Working with one myself now as a friend once the "expert" concept became friend.
In the case of Fresnels in the 1980's, assuming incandescent lamps still in use, it would be bad to hang such a light upside down as they were base down to horizontal rated. Normal Halogen lamps are universal angle burn, but would also let the gel frames fall out if hung up-side down. And good catch on your part - maintenance staffs often need checking up on and inspiration so as to become involved instead of 9:5 hindering. Working with one myself now as a friend once the "expert" concept became friend.
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