Film-Tech Forum ARCHIVE: flaking reflector

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Posted by Darren Fox (Member # 1361) on 02-09-2003, 05:55 PM:

I think I know the answer to my problem aready, but I'm looking for further details. The reflector in one of our booths is flaking a fine silver material. It's a Simplex XL with a Xetron XHN lamphouse. This lamphouse has always burned hot, but after putting in a new bulb recently, the heat level has gone way up. To the point of shutting down the lamphouse last night. When installing the bulb I noticed that the person who installed the previous bulb had not put the cover back on the internal blower. So the bulb was not properly being cooled. This, I believe, explains the damage to the reflector. So a new one must be ordered. So I guess finaly to my questions:

1. What is the process for installing a new reflector?

2. Since I have never done this and this theater is lacking in most tools and adjustment equipment is it best to call in a professional?

3. Does anyone know of good technicians in the Lawrence, KS area?

I have only recently gained control of this theater from the previous owner and many problems exist. It seems every time I fix one, three more pop up because of poor maintainence in the past. We've got shaky pictures, oily lenses, and heat/exhaust issues to name a few. I have at least got the projectionists on their way to proper booth work. Break-down and build-up have improved immensely. I don't want want to wind up on the You suck! list. Any tips you might have on the reflector and for a new manager would be greatly appreciated.

Posted by Paul G. Thompson (Member # 655) on 02-09-2003, 06:54 PM:

I have always had bad luck with Xetron mirrors flaking, especially in the '80's. How they hold up today, I really don't know. By the way, how old is the mirror?

At that time, most were covered under warrenty. Does anyone know what the life expectancy might be of a coated mirror?

Posted by Mathew Molloy (Member # 666) on 02-09-2003, 07:31 PM:

Recently the day I replaced the reflector in our Xetron lamphouse, the silver already started flaking off by the end of the night. All the fans are working and blowing the right direction too.

Replacing the reflector is easy - I think it was just a screwdriver or an allen wrench.

Posted by Tim Reed (Member # 137) on 02-09-2003, 09:32 PM:

Whatever you do, don't inhale that coating!! It will stay in your lungs permanently. Treat it as hazardous material.

Take every precaution when handling it, to not make quick movements or create drafts which can cause the particles to become airborne.

Also watch your fingers because the flaked coating will stick to them very easily.

Posted by Rick Long (Member # 213) on 02-09-2003, 10:44 PM:

Do you have a heat filter in front of your lamphouse?

Posted by Darren Fox (Member # 1361) on 02-09-2003, 11:38 PM:

I have (finally) gotten ahold of our technician and he is coming out tomorrow. He thinks it may just be the outer coating that is coming off and he thinks it may be salvageable. Hopefully that is the case as these reflectors are not cheap. The lamphouse is only 4 years old, so I would think it shouldn't be failing yet. Concerning the heat problem: has anybody else had problems with the circuit boards burning out on these lamphouses? The one currently installed is supposed to display the hours and wattage but it displays nothing. We also still have the crispy old one that was pulled out a couple of years ago.

Posted by Gordon McLeod (Member # 33) on 02-10-2003, 12:07 AM:

Check out UltraFlat in LA they do excellent recoating and honning of reflectors for xetrons

Posted by John Pytlak (Member # 331) on 02-10-2003, 10:00 AM:

Sound like you do have some lamphouse cooling issues if you have a history of reflector heat damage and fried circuit boards. Probably getting less than optimum lamp life too. Have your theatre tech verify the airflow is correct and unobstructed.

Posted by Michael Rourke (Member # 1142) on 02-10-2003, 01:11 PM:

I had a similar problem with my SLC-20 and when I replaced the reflector I also added a stack booster fan to the exhaust. This will protect your new reflector and should add to your bulb life.

Posted by John Walsh (Member # 168) on 02-10-2003, 10:13 PM:

With a lamp only four years old, you *might* be able to get another. Recently, a reflector flaked on us and we were given another after the orginal was examined. The trick here though is you have to be without the reflector while it's being evaluated.

Since the previous person forgot the access cover, I'm sure that's the reason the reflector flaked. So you will need to buy a new one. But, after, why don't you send the old one back to Neumade/Xetron and let them evaluate it. I have found them to be very fair about stuff like that. If it looks like it was coated improperly at the beginning, they will tell you.

You should check the airflow (cfm) for the lamp. If it has always been hot, perhaps the fan on the roof is not larger enough.

I'm not sure of the exact type lamphouse you have, but on most of them there is small fuse on that PC board. It powers the digital volt/amp meter and unplugs from a socket. It is made by Littlefuse and is called a "Micro" fuse; part number 273.250. It does not look like a fuse, so often people overlook it.

Posted by Paul G. Thompson (Member # 655) on 02-10-2003, 10:27 PM:

John said:

quote:
Since the previous person forgot the access cover, I'm sure that's the reason the reflector flaked.

Indeed. It is surprising how many covers I have seen were not properly secured when I was in the field servicing.

Another thing that will kill the mirror is the way the power ladder is designed. To shut the lamp down, Xetron just simply dumped the blower motor power, and let the airflow switch shut down the power supply contactor. That's just like holding a blow torch about 2 inches away with little or hardly no air circulation between the bulb and the mirror until the anode cools. Furthermore, I have seen some "charred" lamphouses where the airflow switch stuck, and the lamp would stay lit and self distruct.

I would hope Xetron modified their power ladder to shut down the power supply and leave the blower running by now, but I don't know if they have.

Posted by Aaron Sisemore (Member # 145) on 02-11-2003, 02:02 AM:

quote:
I have seen some "charred" lamphouses where the airflow switch stuck, and the lamp would stay lit and self distruct.(sic)

This is exactly what happened to me back in 1986 after I had closed for the night and went home. about 5 hours later the janitors called the manager who in turn called me, saying that there was a burning small and smoke coming from the booth (I am suprised they didn't call the fire department) I came down at 5am to see what the hell they janitors were seeing, and sure enought i smelled burning plastic and saw wisps of smoke coming from the portglass. I entered the booth and the room was filled with acrid gray smoke, and the lamp [Xetron XH2000] was ON. I went in and started the exhaust fan to clear the smoke from the room and killed the 3-phase feed to the rectifier. After allowing about half an hour for things to cool down (the lamphouse was too hot to touch!) I opened the lamphouse to find that the heat had melted most of the plastic parts of the lamphouse down to almost nothing (amazingly nothing shorted out!), Actually I was quite suprised that the bulb hadn't exploded- It was black as night on the inside however. and the reflector was badly discolored, especially at the top.

By 8am I was able to get the manager to call in a tech [Dan Eiseman] to attempt to repair the damage, bypass the blower vane switch so that the lamp goes off when the power is shut off, and amazingly they managed to repair most of the innards of the lamp and got us back on screen that night!!! [Smile]

-Aaron

Posted by Scott Balko (Member # 438) on 02-11-2003, 09:31 AM:

That deal with the power ladder is where my bulb life was going also. When I took over here, the automation would shut the lamp down, but that meant it also killed the lamp blower. Needless to say, the bulbs were suffering severely. For now, I shut the lamps down manually and leave the fan inside the lamphouse as well as the roof fan run for at least 15 minutes. Voila!! No more trouble. (Except for the pain in the ass of having to shut down manually) [Frown]

Posted by Paul G. Thompson (Member # 655) on 02-11-2003, 01:55 PM:

Scott, the orginal ladder used 208 volts on those things if memory serves me correctly. So was the elapsed time meter. The meter was across the 208 volt ladder. One modification I made was to hotwire the blower and use a relay in-line with the ladder to extinguish the lamp with automation control because I was never very fond of putting the automation directly in line with the 208 volt interlock. Some unsuspecting tech that is not aware of the Xetron's automation loop operating at 208V could cause some safety issues.