Source Four Leko for Filmmaking - lamp burned out immediately

Benjamin Handler

Member
Hello all,

As title suggests, I bought a Source Four Leko 750 to use for indie filmmaking. I have some experience with these lights from working as a volunteer stagehand and periodically on film sets, but am by no means an electrician and feel like I'm in over my head. Saw lots of good info on this forum, figured some of you all could advise me how to move forward.

Within 15 minutes of getting the source four built in my living room, the lamp burned out. I had the light plugged into a 1000w impact dimmer, and was testing the dimming level when a flicker happened and the lamp died. To note, the dimmer added a noticeable hum to the light. The more I dimmed, the louder the hum.

Specs:
Source four leko 750 (purchased from usedlighting.com)
Ushio HPL Lamp (750w/120v)
Impact D-1000 AC Dimmer Control 15-Amps
Edison Plug (15amp/125v - I replaced the bates plug with this Edison from a local hardware store)

I have not checked the voltage of my apartment's outlets. Is that something I should have done? Will I need to do this with every outlet I use? (planning to use in residential houses for an evening sun effect).

I did not touch the bulb prior to placing in the S4, so oils should not have been the issue. Was this probably just bad luck, or am I doing something wrong? Do any of the parts I am using bring up red flags? I used the lamp for about 10 minutes without the dimmer and was not having any issues, my hunch says the dimmer might've had something to do with it.

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FMEng

Well-Known Member
Fight Leukemia
Severe vibration from an unfiltered dimmer could certainly be a factor. Stage dimmers have inductors to smooth the waveform and reduce filament sing. Inductors are too big to fit in something made to fit in a standard electrical box.

It seems to me that an S4 for close range video is way, way overkill, and not well suited for video. If you dim it, the color temperature is going to shift drastically yellow, affecting the color of your results. Most video folks prefer, big, diffused light sources, with a stable color temperature. Fluorescent and LED are widely used for video.

Nic

Member
Like you, I’m not an electrician but here’s what I can tell you.
I agree with your assessment of the likely cause here. To expand on what FMEng said, the dimmer you have is a phase control dimmer. Basically, it switches the power on and off very quickly to “dim” the light. These are known to cause lamp sing and I’m not surprised it would cause filament damage.
What you really want is a sine wave dimmer which reduces voltage while still outputting constant power.
If you don’t want to buy a new dimmer, you might try a 575w lamp so that you’re dimming the instrument by a lower percentage (I don’t actually know if this will work, it’s only an idea). You could also use light modifiers like scrims instead of dimming.

theatricalmatt

Well-Known Member
As an aside, Source Fours (and most other theatrical and film lighting fixtures) are marked "Not For Residential Use."

Benjamin Handler

Member
Thank you all for getting back to me on this so quickly.

Regarding dimmers, could a simple solution be simply switching to a sine wave dimmer? There seems to be some cheap pre-made options online. Could something like this be a good alternative to the impact dimmer I have?: https://www.fullcompass.com/prod/15...taW_8P4lM-YipQSG92vwDhxJS8ranQrsaAqGsEALw_wcB

Regarding S4 lekos for video: I'm basing this mostly off David Mullen's work (Marvelous Mrs. Mazel being his best-known). He uses source-fours to create hard slashes of light. Easy to use indoors without a ton of spill on walls. Lots of other practical uses, too. If curious, see some examples here: https://cinegleaner.postach.io/page/day-int . For the price, I figured it was worth a try, as a joker 400/800 (commonly used) of similar power in a Leko attachment is around $5000. Good point, Matt. Most of the time David has the leisure of a generator and isn't on house-power. I typically don't have a generator. would household electrical outlets be an issue here? Most of my other fixtures run off battery, so the S4 would be one of few fixtures I'd be plugging into a household outlet. I will also pick up a 575w bulb. Scrims also a good call. I will usually not need full power, anyway. Thanks! theatricalmatt Well-Known Member Hi Ben -- I believe the restriction on residential use has more to do with heat than electrical power, the same reason small halogen lamps in torchieres, so very popular when I was growing up, were removed from the marketplace. Between the heat off the lamp cap, and the heat from the beam of light -- at a much, much shorter throw than its intended use in a theater or soundstage -- it's very easy to start a fire. Houses also tend to have a lot more fabric (curtains, sofas, rugs, etc) than in a theatrical or architectural installation. Power *is* a bit on an issue, as many household outlets may be rated at 15A, but the service shared between multiple locations in the same house. Or backed with only a 10A breaker, or run with only 18ga wire.... the problems are numerous, and household and apartment buildings get inspected much less frequently than commercial or industrial spaces. So please, please be careful. BillConnerFASTC Well-Known Member I don't consider your use in a residence to be residential. Now, start using it for long periods to read a newspaper or prepare meaks, and that's probably a bad idea. The back end of an S4 against drapery would be not good. Les Well-Known Member Honestly, I think you got a defective lamp. As a side note, these lamps can be very susceptible to mechanical shock (bumping). Last edited: microstar Well-Known Member Thank you all for getting back to me on this so quickly. Regarding dimmers, could a simple solution be simply switching to a sine wave dimmer? There seems to be some cheap pre-made options online. Could something like this be a good alternative to the impact dimmer I have?: https://www.fullcompass.com/prod/15...taW_8P4lM-YipQSG92vwDhxJS8ranQrsaAqGsEALw_wcB Regarding S4 lekos for video: I'm basing this mostly off David Mullen's work (Marvelous Mrs. Mazel being his best-known). He uses source-fours to create hard slashes of light. Easy to use indoors without a ton of spill on walls. Lots of other practical uses, too. If curious, see some examples here: https://cinegleaner.postach.io/page/day-int . For the price, I figured it was worth a try, as a joker 400/800 (commonly used) of similar power in a Leko attachment is around$5000.

Good point, Matt. Most of the time David has the leisure of a generator and isn't on house-power. I typically don't have a generator. would household electrical outlets be an issue here? Most of my other fixtures run off battery, so the S4 would be one of few fixtures I'd be plugging into a household outlet.

I will also pick up a 575w bulb. Scrims also a good call. I will usually not need full power, anyway.

Thanks!
From the few specifications available, there is no mention of the TecNec 43060-0VGA being a sine wave dimmer. I doubt it could be, considering its price.

DrewE

Well-Known Member
Most theatrical dimmers are not sine wave dimmers, though they may (i.e. probably do) have better filtering than most residential dimmers. I'd also be inclined to suspect a bad lamp if nothing else obvious comes up to explain the problem (such as a bad socket or mechanical stresses/bumping), albeit without a ton of experience to base that inclination on.

One appropriate option for a sine wave dimmer is a variac, naturally taking care to get one with a suitably sufficient power rating. I would be very surprised if the TecNec unit is anything other than a typical phase control circuit, basically a beefy household dimmer or power drill speed control switch in a slightly different box.

RonHebbard

DELO72

Well-Known Member
First up, the dimmer likely had nothing to do with it. You can easily use (and I have many, many times) a standard Lowes/Home Deport rotary resistance dimmer and it'll work fine (if rated for the right wattage).

Also- your home outlet provides plenty of power. Home outlets are 15A, 110-120V. (That's 1650-1800W max draw before you trip a circuit breaker). mind you- that's total draw from all outlets for that room, that are on the same breaker.

It's most likely you had a lamp with a weak filament that had taken rough shipment and was prone to failing as a result. Take a look at the contacts in the fixture's socket, and make sure those look good (brass looking vs. black or corroded.) so you can rule that out as a factor.

Senior Team

Lynnchesque

Well-Known Member
It should be noted: It is common practice to adjust the pan/tilt, focus, and shutters with the light hot and on. It shouldn't be so fragile that those movements cause a failure.

derekleffew

Resident Curmudgeon
Senior Team
It shouldn't be so fragile that those movements cause a failure.
Agree, but I bet you've never used an FLK lamp, have you?