Conventional Fixtures Shakespeares blowing lamps

[egilson1]

So My buddy in Chicago land (not a lighting person) had a pallet of some old Shakespeares. He swapped the connectors to edison, and is now having an issue with multiple lamps in multiple caps burning up after a few seconds. Lamps are ushio EHDs and are not new. voltage is running about 122-124 volts. I think its just aged lamps. anyone have any thoughts as to why they might have such a high failure rate? Is it the voltage? I wouldn't expect 124v to do that to a 120v rated lamp.

Thanks,
Ethan

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[Mac Hosehead]

Wow, does not look like just old lamps to me. The one pin visible on the lamp in the photo looks discolored/bad. The envelopes look similar to a gas leak. How were these tested? I'm always suspicious of over-heating.

 

[microstar]

It looks like all the shutters are still pushed in. If he operated them that way I imagine it wouldn't do the lamps (or the shutters) any good.

 

[RonHebbard]

So My buddy in Chicago land (not a lighting person) had a pallet of some old Shakespeares. He swapped the connectors to edison, and is now having an issue with multiple lamps in multiple caps burning up after a few seconds. Lamps are ushio EHDs and are not new. voltage is running about 122-124 volts. I think its just aged lamps. anyone have any thoughts as to why they might have such a high failure rate? Is it the voltage? I wouldn't expect 124v to do that to a 120v rated lamp.

Thanks,
Ethan

View attachment 20764h

Any vibration / rough handling involved during focusing?

Is it their standard practice to snap stone cold filaments to 100% to focus Vs. loosening the fixtures prior to lighting them?? (What? You mean I should know which fixture I want to focus BEFORE the board op' has lit it to full so I can find it in the dark???)

Too many times I've worked with folks who won't consider focusing at any thing less than 100%, neither would it cross their mind to loosen a fixture PRIOR to snapping its stone cold filament to full, THEN they muscle it lose once it's heated and SHAKE the poor little aging filaments to bits.
EDIT: Calling @DELO72 @ship
Toodleoo!
Ron Hebbard

 

[Amiers]

I agree with Ron.

Rhe only other way these could of fast blow was to wire the plug end wrong. But the plug would be fried to soooo.....

 

[TimMc]

I don't suppose anyone metered the voltage at the business end of the extension cord, eh?

 

[DrewE]

Are these being ramped up with a dimmer, or switched on cold to full power instantaneously?

 

[RonHebbard]

I don't suppose anyone metered the voltage at the business end of the extension cord, eh?

While the circuit is under load, most conveniently accomplished by inserting a two / fer with a typical fixture connected to one side of the two / fer leaving the other side available for convenient metering.
Toodleoo!
Ron Hebbard

 

[RonHebbard]

Are these being ramped up with a dimmer, or switched on cold to full power instantaneously?

You mean like I enquired back in post #4?
Toodleoo!
Ron Hebbard

 

[derekleffew]

Now I'm no expert like @DELO72 or @ship , but I say those dead lamps look like pinch-seal failure rather than over-voltage or thermal or mechanical shock.

Also, why use EHD when GLx is available and (if I'm not mistaken) what the Shakespeare was designed for?

 

[egilson1]

no dimmer. Just hot on. I mentioned that when HPLs first came on the market that since they were 115 volt we had to stop hit flashing fixtures to check them in.
122-124 volts at end of cord.
These have been sitting on a shelf in a warehouse for some time, with not specific intent on their use.

 

[DELO72]

Over-voltage will shorten the lifetime. Shouldn't make them pop after a few seconds. Especially if they were new(ish) lamps.

1) Check the lamp pins and the socket contacts. Are they charred/corroded at all? If so, you have an electrical resistance issue (and heat build-up) that will lead to early failure.

2) are the plugs wired correctly?

3) did the lamps possibly get unseated when the fixtures were moved (fallen slightly out of the socket, making a poor electrical contact?-- see #1 above)

4) does the building get power surges? A brown-out or surge will do that.

The lamps look End-of-life, but it's hard to determine what caused that effect without inspecting them and the fixture. The "Were the shutters all in?" was a good question to ask as that will overheat the lamps, and prematurely age them.

 

[DELO72]

Also, why use EHD when GLx is available and (if I'm not mistaken) what the Shakespeare was designed for?

Because GLC/GLA, etc. are all 115V. They'll die fast if you put them on 123V power. Better off in this situation with a 120V lamp. Still not perfect, but better chance of getting any life out of them.

 

[TimMc]

no dimmer. Just hot on. I mentioned that when HPLs first came on the market that since they were 115 volt we had to stop hit flashing fixtures to check them in.
122-124 volts at end of cord.
These have been sitting on a shelf in a warehouse for some time, with not specific intent on their use.

I had to ask because a decade or so ago we supplied a tungsten followspot for a hotel ballroom gig. Client plugs it in, hits the switch.. and POOF. Okay, that happens. We had sent a spare lamp, client replaced it and.... POOF. Aside from trying to find a lamp in a small city on Saturday morning... it turns out the hotel had a 120V Edison outlet wired for a piece of food service equipment - 240V. Not labeled, not marked in any way as "warmers only" or such.

When I went to the venue and found out what was going on, I removed the outlet, cut the neutral all the way back to the conduit, and put a wire nut on the hot line..... and piece of tape over the hole in the cover plate. Screw 'em.

 

[derekleffew]

122-124 volts at end of cord.

The most accurate method I've found of measuring (almost) socket voltage:
Plug a two-fer inline just ahead of the fixture, into the cable/jumper/pigtail/plugbox.
Run the dimmer to 100%.
Using a true-RMS VOM, measure the voltage at the unused female of the two-fer.

In this case, hope that you can get a reading before the lamp blows.

 

[FMEng]

If the concern is over voltage, you don't really need to measure with a load. The voltage can only stay the same or decrease from the no-load reading, depending on wire size and distance from the panel. The need for true RMS comes into play when measuring the output of a dimmer or an inverter.

 

[derekleffew]

If the concern is over voltage, you don't really need to measure with a load. The voltage can only stay the same or decrease from the no-load reading, depending on wire size and distance from the panel.

While you are technically 100% correct, I feel your approach yields an incomplete answer. Personally, I'd much rather know that "the socket voltage of a fixture on my third catwalk is xxx.x," rather than "the voltage in my venue is something less than yyy."

 

[ship]

First lamp in hand shows a finger Fu@&. (Dirty hand or something impure on the outer globe - the tungsten silver particals collecting up on the outer globe). Other lamps if not all during transport might have been bench focused badly in lamp touching reflector. Big bounce on a used lamp could also do this. Shock in as mentioned transport to crack a seal. Osram has the best free PDF manual on lamps, which includes reasons for failure. Though one addition I would add more in depth on, is in the was the dirt on the quartz globe reflecting or absorbing the heat. Big difference and should be tell tale in what specific Fu@& was the cause of the failure. Laid out what causes the reflect or absorbsion or the filament during the "halogen effect" can help diagnose problems in the theater space where the fixtures were or in theater management training problems.

Details for later once the scientists are re-hired. (I have not inspected a bad lamp in six months now.)

Changing plugs should not result in what is seen in the bad lamps. A closeup of the pins (Same style photo but about the lamp pins) could reveal a bad lamp socket base. Just a thing, but also doubtful it would cause an envelope gas failure as evidenced by the lamps in general. Closeup of the lamps can reveal the cause of this in looking for a crack or black spot. Where did the gas get out?

 

[Radio]

no dimmer. Just hot on. I mentioned that when HPLs first came on the market that since they were 115 volt we had to stop hit flashing fixtures to check them in.
122-124 volts at end of cord.
These have been sitting on a shelf in a warehouse for some time, with not specific intent on their use.

Recommend you switch to GLC , FLK, or HX601 lamps. HX601 rated for 130v.

 

[DELO72]

Recommend you switch to GLC , FLK, or HX601 lamps. HX601 rated for 130v.

GLC, FLK and HX601 (another name for the FLK) are all rated at 115V, not 130V. They will die VERY early on if they are getting 122 - 124V. The OP does NOT want to go this route if they want to stop replacing lamps.