Loud buzzing from LDR Canto 1200 Spotlight

[petercav17]

Hey all,

We just got 2 new LDR Canto 1200 spotlights a couple of days ago. Due to a shipping/packing error we only received one lamp, so I was only able to test the one. I assembled it and fired it up and it works great, but there is a really loud buzzing sound coming from the lamp. We can hear it all the way across the theater, and the Artistic director has complained about it. I've been close to HID spotlights and movers many times but I've never heard a buzz this loud before. Granted, it is 1200 watt lamp, but is this normal? I had assumed that it was okay since it works fine, but I just want to double check that isn't something wrong with it.

Thanks!

 

[Les]

I'm not sure if the ballast is built-in to the lamphouse or not (and I'm too lazy to look it up), but have you checked that? I've never heard an actual lamp buzz very loudly - a large metal halide might 'ring' a bit. But buzzing usually resonates from the ballast. Check that it is tight.

 

[BeastDK]

Well, we have one of those, some years old, and as Les says, there should not be any noise coming from the lamp itself. Have had noise from the external ballast, solved with tightening and silicone.

Sincerely
BeastDK

 

[petercav17]

I'm not sure if the ballast is built-in to the lamphouse or not (and I'm too lazy to look it up), but have you checked that? I've never heard an actual lamp buzz very loudly - a large metal halide 'ring' a bit. But buzzing usually resonates from the ballast. Check that it is tight.

Yeah it has an external ballast, but the buzzing is very clearly coming from the lamp. I reseated the lamp but that didn't seem to help.

 

[WayfarerAM]

Have you tried the lamp in both lights? If the buzzing follows the lamp it may be a lamp issue. If it's specific to one light I would try checking the wire lamp leads and ensure they are tight. Also a fan might be the problem since sometimes they only kick on with the lamp. A ballast issue is also possible but unlikely. Won't hurt to try swapping those if its not terribly difficult. They might als have meter test ports. Try checking the voltage AFTER the lamp is struck and compare it to the spec.

I haven't personally used the light so I'm just thinking out loud.

 

[JD]

Don't have the paperwork but on HMI's with an external ballast the ignitor module (which is a transformer) is still usually in the lamphouse and may be the source of the noise.

 

[RickR]

On a brand new fixture I would look for a loose part, starting near the fan.

 

[petercav17]

I just got new lamps in and was able to get the other unit up and running and the sound was consistent, so I guess it is normal after all. Thanks for all the help!

 

[PeteEngel]

Sorry you have to deal with a noisy followspot. Also, do not close the Iris on the Canto for longer than 10 minutes. You will Void the warranty (page 4 of User Manual).

 

[JohnD]

What do the vendor these were purchased from and Canto tech support have to say? Is this noise usual?

 

[JD]

Sorry you have to deal with a noisy followspot. Also, do not close the Iris on the Canto for longer than 10 minutes. You will Void the warranty (page 4 of User Manual).

Good rule of thumb on all followspots. All that output hitting the thin blades of the iris will wreck it. Depending on the sequence in the lens train, always use the blade douser during blackouts. Some spots have a forward fader for smooth blackouts (Lycian comes to mind) and you can end up with that closed, no output, but your Iris and Gels cooking. (Not the case on the Canto)

 

[dijaseedat]

ballasts are transformers, and they are built with laminated steal core plates, when the plates get loose they hum very loud, they still work but annoying , you could put a bead of epoxy across them and secure them, the electromagnetic force induced by the circuit cause the plates to vibrate and over a long time come loose and buzz. That's my two cents.

 

[PeteEngel]

Good rule of thumb on all followspots. All that output hitting the thin blades of the iris will wreck it. Depending on the sequence in the lens train, always use the blade douser during blackouts. Some spots have a forward fader for smooth blackouts (Lycian comes to mind) and you can end up with that closed, no output, but your Iris and Gels cooking. (Not the case on the Canto)

Yeah, except that isn't the case with any Robert Juliat followspots. Quiet and iris able to handle being completely closed (standard RJ feature). All followspots are not created equally. I'm a bit biased though.

 

[jwh78]

We have the exact same spot. Only sound it makes is fan noise.

 

[dijaseedat]

I have a halide bulb, it has an anode or plate wire that goes to end of bulb and a dimple in glass envelope I shook it and it rattles or rings, your talking about ballast vibrations that could radiate to bulb. Solution off the top of my head, remote the ballast out of the light fixture, or what I think is way easier is put or tie with none magnetic wire, a neodyanamium magnet the most powerfufl magnet in the world, at tip of light, use gloves to not leave any heat spots on glass envelope. The magnet should secure the anode or plate wire so it wont rattle against the glass envelope.

 

[PeteEngel]

I have a halide bulb, it has an anode or plate wire that goes to end of bulb and a dimple in glass envelope I shook it and it rattles or rings, your talking about ballast vibrations that could radiate to bulb. Solution off the top of my head, remote the ballast out of the light fixture, or what I think is way easier is put or tie with none magnetic wire, a neodyanamium magnet the most powerfufl magnet in the world, at tip of light, use gloves to not leave any heat spots on glass envelope. The magnet should secure the anode or plate wire so it wont rattle against the glass envelope.

Wow... I can't even think of how to start counting the ways doing something to the lamp is a bad idea.

One thing you might want to do is find out what your voltage is under load. If your voltage is low it may be giving your fixture fits.

 

[dijaseedat]

well I dont want to talk in a condiicending manner here, I have a friend he worked at general dynamics where they built the f16 fighter aircraft, all the engineers couldnt figure out a problem but he saw it as plane as day, sometimes the easiest fix doesnt make sense, sometimes its just common sense. you can look for all the engineering stuff on the internet to the endth degree, but what about physic that you learned in high school!. Im not trying to make enemies here, just trying to help, get a magnet and a file file a v grove to hold wire, get some copper wire tie wrap it on end of bulb, Its simple, Im old, and alot of stuff these days is fading away, you dont always need an engineering degree to fix stuff. Just some common sense......

 

[MNicolai]

Really bad advice. Those lamps are pressurized substantially underneath room temperature. At operating temp, they're explosive. You don't want to do a single thing to degrade the structure of the lamp. At best, you'll blow the lamp up in your Canto and ruin your reflector, lamp housing, and socket. At worst, you'll expose yourself to a dangerous scenario where the lamp explodes while you are in close proximity to the fixture.

 

[PeteEngel]

well I dont want to talk in a condiicending manner here, I have a friend he worked at general dynamics where they built the f16 fighter aircraft, all the engineers couldnt figure out a problem but he saw it as plane as day, sometimes the easiest fix doesnt make sense, sometimes its just common sense. you can look for all the engineering stuff on the internet to the endth degree, but what about physic that you learned in high school!. Im not trying to make enemies here, just trying to help, get a magnet and a file file a v grove to hold wire, get some copper wire tie wrap it on end of bulb, Its simple, Im old, and alot of stuff these days is fading away, you dont always need an engineering degree to fix stuff. Just some common sense......

HAHAHAHAHAHA....errr... Sigh. Yeah, don't do that. For many MANY reasons. Not the least of which is that it isn't the issue in the first place.