The lamphouses are Xetrons (XH, I believe. The blue ones.) The rectifiers are IREMs. We are burning 2000 watt bulbs, mostly Christie but our warehouse people have been sending us these ones from LTI. (Strong?) We should be getting 1500+ hours out of a bulb but it's rare that we get one to last 500 hours. Some are even failing at 100 hours.

When a bulb fails, it usually turns all black inside and the metal ends turn black and blue. Once in a while it will degass itself and fail all at once. Other times it will work well for a while but then gradually blacken until it's useless. To me, these are classic signs of the bulb overheating, right?

All the the blower and exhaust fans have been checked and they are all working. As a matter of fact, one of the things we did was clean out all the dust bunnies in the fans and ducts. I don't think there's a problem with air flow, anyway.

I was at the theatre myself just a week ago and I personally checked all the current and voltage readings. They are all burning at anywhere between 70 and 75 amps. All the voltages are reading 25 to 26 volts. This was one of the first things I checked when I got there.

Another thing I have been thinking is that the bulbs aren't focused/aligned properly in the lamphouse. I understand Xetrons are picky about this due to the reflector design. The way I hear it, the aspherical reflector will bounce a hot spot back onto the bulb if it's not set correctly. I just had them double check for focus and they tell me that it's right. Is there any truth to this? If so, what's the secret?

Finally, I have heard that these lamphouses may be picky about the brand of xenon bulb they use. From experience, I know that CFS consoles don't like ORC bulbs but work well with Christies. I don't see why this wouldn't be true. I have also spoken to people who have managed that theatre in the past and they all seem to agree that Osram bulbs work well in these lamphouses. What's your experience with this?

I just went through the manual to this lamphouse and there isn't anything specific about this. At this point I'm just about out of ideas. What else can you tell me?
Any help is greatly appreciated.

Is this a new problem? If so, what changed recently? Someone bang the lamp house real hard running through the booth and knock something loose inside?

I've only been at this for a year now so I don't know the entire history of this booth, but from what I hear this has been a problem that crops up from time to time. It just seems to have gotten worse since the beginning of the summer.

I was thinking about an exhaust blower right on top of the lamphouse, too. Kind of used as a booster, right? The way I figure it, you can (almost) never have too much air, eh? I'm beginning to thing that I'm going to have to go back there and climb up on the roof and inspect the exhaust systems myself.

 |  IP: Logged

Steve

 |  IP: Logged

 |  IP: Logged

On the other hand, the blower on top of the reflector housing doesn't seem to be too healthy. It runs but doesn't seem to be drawing well. Just enough to trip the paddle. (There isn't a paddle in the roof exhaust duct.)

I'm hoping it's just a case of dust bunnies, still. I plan to take the whole blower apart and clean the heck out of it and give it a little bit of oil. (Which I'm sure it hasn't had in a long time.)

One other thing. There is a half circle shaped cutout in the rear flange of the reflector. Does that have to be facing in a certain direction? I imagine it's supposed to be facing up so as to capture the air stream from the blower and allow it to go down the length of the lamp, for cooling. Is this right? If so, the cutout is facing to the side. If this isn't right, I'll just rotate the reflector and reposition it.

Yes, Paul, the metal ends are discoloring. My first instinct was too much heat but they convinved me that all the blowers were working... which they APPEARED to be at first look but now it seems to me that it realy IS the problem.

Paul

 |  IP: Logged

 |  IP: Logged

 |  IP: Logged

The basic design is a squirrel-cage blower mounted in the rear where the XYZ adjustments are. The airflow blows down into a plenum to cool the rear; turns right at the bottom of the bulb holder assembly. The air then is supposed to blow up, out of a hole (next to the front bulb support) in the front to cool the bulb. A tube (actually square-shaped) channels the air to the bulb connection in front.

Some models had the safety vane switch mounted on the blower intake; some in the plenum. Some drew in air from the nonoperating side of the lamp; some from the back. Some had one fan (on the plenum); some had two (plenum and stack) some had three fans (plenum, stack and bulb front.) Some had a heat filter in front (which restricted air into the lamphouse) some did not.

Did the problem just start, or has it always had this problem? Perhaps the Dayton blower(s) are shutting down when no one notices (the thermal-safety cutoff switch inside the blower.)

Are the correct bulb adapters being used? Perhaps a wrong adapter is installed, positioning the bulb too far forward (or back)?

I don't think the half-circle cutout is related to cooling; IIRC, it's to allow the assembly person to remove the fixture that positions the reflector inside the similarly shaped holder. Also, on some reflectors, there are only three mounting screws, so it can't be rotated to some 90' positions.

And the CFM should be measured; can't go by feel.

It's just started happening worse in the last three months or so, but they tell me that these lamphouses have always been hard on bulbs.

It has the cooling intake on the rear of the unit, just above the control switches. The proof paddle is inside the duct, just behind the grating. There are heat filters inside the snoot.

We were up on the roof, yesterday and we took the covers off the exhaust fans. They are all working and the belts have just been recently replaced.

I don't have an air flow meter but I used the standard measuring device that I always use... I pull the pipe off the top of the lamphouse and push it aside. Then I hold something that makes smoke... (light a match and then blow it out or some cigarette smoke or whatever)... about 2 feet away from the end of the tube, at an angle. The smoke will be immediately sucked up the tube, in a straight line. It passes the test with power to spare, actually.

I just think the blower on top of the plenum is getting tired. It's probably got dust down in the bearings. They did a cleanout of the pipe in the back, recently and I imagine that some of the dust got knocked loose and went down in. I'm sure they weren't running too healthy before that, though.