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SL issue

Discussion in 'Lighting and Electrics' started by dj_illusions, Dec 5, 2007.

  1. dj_illusions

    dj_illusions Active Member

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    hey,

    I have a troublesome Stand SL at the moment, to date it has blown 6 Lamps and I dont really want to try anymore.
    Basically within 5 minutes of putting a new bubble in the fixture it will blow, it is paired with another lamp so i know the fault is in this lamp.
    i have tried a different patch and dimmer to no avail, i have also put the lamp over a test and tag machine and it passed all tests. im at a loss and cant think of any more reasons as to why it would be doing this, can someone help shed some light on the situation???

    cheers
     
  2. zac850

    zac850 Well-Known Member

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    Open up the cap of the fixture, check for bad contacts. If it is getting just flashes of power, that could severely decrease lamp life (I mean like on and off every 1/10th second).

    I assume your not touching the glass of the lamp when you re-lamp it?
     
  3. avkid

    avkid Not a New User Fight Leukemia

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    To add to what Zach said, you aren't doing something silly like putting in cold lamps and cranking it up 100% are you?
     
  4. icewolf08

    icewolf08 CBMod CB Mods

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    Even cold starting the lamp should kill multiple in a row in a matter of seconds. If you bought all the lamps at the same time, you might try on in a different fixture to see if you got a bad batch of lamps. If you did, and you still have the bad ones, you might be able to get them replaced. After that, check the connections in the connector and in the lamp base. As was mentioned, a bad connection can do lots of damage. You might also check the connections in the leg of the 2fer you are using. If the lamp base is burned out or charred, that could be your issue, and it isn't that hard to replace those. And back to lamps before I go, check to make sure you have the right lamps. There could have been a mixup at the shop and they might have given you the wrong voltage lamps, which would leave you hosed.
     
  5. Lightingguy32

    Lightingguy32 Active Member

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    try running a preheat macro of some type before firing the lamp up all the way to full. Other wise check the dimmers trim (i don't know if this is necessary) some times the high side of the trim is a little over what it should be and can shorten lamp life and pop new lamps or cold lamps. What do the lamps look like after they blow (just a melted filament or is there a black char mark on the glass envelope)
     
  6. JD

    JD Well-Known Member

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    You know, I had a fixture like that once. Ate lamps for no real reason. Bulbs, contacts, electric, all good. I finally (think I) figured it out. It was just a quirky reflector alignment. (Altman fixture.) The light output looked fine, but my guess is it just found a bad spot where it was directing a lot of output back to the filament. On a hunch, I misaligned the socket by running the screws all the way out, then realigned it but with all the screws a bit further in. (had a center-point screw.) Worked great after that. Don't know if this will help, and can't remember all the details as it was in the 1970's, but who knows!
     
  7. dj_illusions

    dj_illusions Active Member

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    Hmmm.... The contacts are fine, I have not touched the glass although phillips make it hard now they dont give you the rice paper bags with the lamp...

    I can rule out any dimmer trim as the lamp is paired with another identicle SL on the same dimmer and patch, i have also swapped dimmer and patch and the problem was still present with this lamp only. It is not a faulty batch of lamps as I replaced another one of our 12 SL bubles with a lamp from the same batch.

    The reflector issue is interesting, I mgiht have a look at it and see if it is alinged correctly, short of that i might have to send it off to get serviced which i was trying to avoid as the company that service strand here charge like a wounded bull!!!
     
  8. MircleWorker

    MircleWorker Member

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    The best lamps I use in mine are Phillips Broadway. I tried using other brands and not having them last as long.
     
  9. ship

    ship Senior Team Emeritus Premium Member

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    I like this idea given the lamp base is good - (True RMS or Analog) multi meter the voltage for any spikes and voltage at full at the location the fixture is plugged into. (You will need to test this while the dimmer is under load by at least 75w.) And as said what does the blown lamp look like? Take a photo if possible there is certain things you can observe about the bad lamp that will tell you a lot. I also like JD's idea to check the bench focus. I also have blown a few lamps the same way in the past by way of in my case the lamp touching the reflector during bench focus or while screwing the lamp cap in and that pressure against the reflector breaking the pinch seal.
     
  10. dj_illusions

    dj_illusions Active Member

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    Ship, the blown bubbles out of the lamp look perfect, clear glass just broken filament, there is no other visable damage to the lamp. 1 had a slight black bit on the glass right where the filament had blown.

    Someone else suggested it may be a thermal short not a dry short that is only occuring once the lamp has reached a certain temperature. I am currently working on getting the back off the lamp to see the wiring under the lamp base but the screws seem to have seized up due to heat or strand have a thing with doing screws up too tight...
     
  11. JD

    JD Well-Known Member

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    Interesting. Unusual for the filament on a new lamp to just break unless vibration is involved. Anything around that fixture that might be a source of vibration like a bad air handler? Maybe it's mounted in just the right way were the lamp is catching the shake or vibration.
     
  12. Lightingguy32

    Lightingguy32 Active Member

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    Could be a run of bad lamps by coincedence that they all landed under the same end user in one shipment. Except that is highly unlikely
     
  13. dj_illusions

    dj_illusions Active Member

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    The SL in question actually hangs right next to the one it is paired with which is on a catwalk FOH, so if it was a vibration issue this lamp would also be affected along with a number of other higher wattage FOH fixtures. Nice guess though, I can see the logic behind the suggestion, and your right it is very much like a vibration break in the filament, or similar to that of a cold strike to full and the filament has just snapped.

    it could just be a really bad run of lamps, they came from our supplier, direct from philips the supplier had not even opened the box there was 8 or 10 lamps however many come in those boxes, 1 of the lamps is in another SL with no issues though...
     
  14. JD

    JD Well-Known Member

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    Sounding like bad lamps. Might have had a lot of vibration stress before the box even made it to you! Generally, when lamps "blow" there is some form of beading at the very ends of the filament where the break arced. If it is a real clean break, the fracture could have been there before the lamp was ever turned on. It may have made contact and the lamp lit, and even fallen apart as it cooled and the tungsten cooled. Strange.
     
  15. Lightingguy32

    Lightingguy32 Active Member

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    It would be very rare for almost an entire box of lamps to exhibit the same problem(s) that caused their failures though. But it is still likely considering that he has probably checked all other parts of the system related to this issue and he found nothing out of whack (good dimmers, no vibration, good lamp base etc.). So I am sticking with the bad box of lamps theory.
     
  16. JD

    JD Well-Known Member

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    I remember a case of lamps I got in once. Two or three failed real soon. I got a new replacement out and right out of the box I noticed a part of the filament rolling around in the bulb! There were 8 more in the case and when I looked at them, two had cracked filaments! Those two actually did light, but I did not use them. Whole thing led to a big argument with the distributor I got them from.

    Bottom line is I'll never know what was up with them. Could have been real rough shipping, or may have been a brittle batch of filaments. I learned one surprising thing about bulbs during the whole ordeal; Not all manufacturers wind their own filaments! (....wait for it to sink in...) Apparently, filament winding is very tricky business, and not all manufacturers do it! Weird world..
     
  17. Lightingguy32

    Lightingguy32 Active Member

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    Were you able to get a box of replacements at no extra charge? If you lose a box like that it only seems reasonable to get a new box at no charge
     
  18. JD

    JD Well-Known Member

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    Yea, there were 24 in a case, so I raised quite a stink!

    Now, I guess I have to clean my desk out, because that was 15 years ago, and I remembered I still had one rolling around in my desk! I looked, and there it was, so I snapped a picture. You can see the clean break at the third filament wrap. (lamp never used.)
     

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  19. dj_illusions

    dj_illusions Active Member

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    i dont know what is more amazing, the fact that the filament has such a clean break brand new or the fact you had that lamp in your draw for 15 years... nice

    im going to ring my contact at phillips tomorrow and sound them out. unfortunately i dont have all the lamps but have all the tags off the tops of the boxes.
     
  20. Lightingguy32

    Lightingguy32 Active Member

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    You had that lamp stored away how long?! Did you keep it as a souvenier to remind you not to buy from that company again or did it mistakenly role into the desk drawer and stay there for 15 years?
     

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