NC2000 prism cleaning

[Dave Macaulay]

OK, I have an NC2000 with its red imager (probably all three but red is really bad) gummed up with popcorn grease and dirt, red's lower right corner is badly occluded. This is about as remote a spot as they come, 195 miles south of the arctic circle - shipping back to repair is possible but not exactly easy or fast and that would close the cinema for quite a while..
Can I clean it? The crud is either on the prism face or the DMD face, don't know. I plan to pull the prism tomorrow and see if I think it's possible to get at those. Any tips greatly appreciated.
I have isopropyl but can "probably" find acetone. The grease will be cooked on pretty solidly.

[Steve Guttag]

The only field cleaning that I am aware of is the space between the two prisms...you can get a tongue depressor with an appropriate swab in there to wipe it. There are companies like Strong that can to advance replacements so you can make it a single trip. You would have to float a lot of money though until everything is checked out. Overall, it is a good investment as you'd be amazed at how much more light one gets after a cleaned prism assy.

[Mark Gulbrandsen]

What Steve said. Its not cheap either... with ANY digital projector its imperative to exhaust the Popper outside the building, and or to use the original NEC heppa type filters. I also reccomend thin foam tape around the face of the filter so oily air can't get past the filter.

[Stefan Scholz]

Environmental conditions for projection systems are stated in advance to a potential buyer, and the clearly state "cat 9 clean air " (to some ISO specs). It also states the surrounding air to be free of dust, soot, oil and grease fumes. If a window can be opened, a proper HEPA filter grade insert must be used instead of the glass pane.
So why does no customer listen to these given rules?
I still find enough setups, which use the 8" blower on the top and ventilate directly to the outside air, to save a little on A/C cost for a circulating indoor A/C system. Thereby drawing tremendous amounts of greasy and dusty air from the building through the projector. As we know NEC casings are not airtight, and enough air creeps through all slits into the machine, bypassing the filters, and leaving a residue of grease and fibers on all surfaces. Once burnt in, the glass surfaces are ruined, after cleaning it will never be reconditioned to the original condition.

[Mark Gulbrandsen]

Environmental conditions for projection systems are stated in advance to a potential buyer, and the clearly state "cat 9 clean air " (to some ISO specs). It also states the surrounding air to be free of dust, soot, oil and grease fumes. If a window can be opened, a proper HEPA filter grade insert must be used instead of the glass pane.
So why does no customer listen to these given rules?
I still find enough setups, which use the 8" blower on the top and ventilate directly to the outside air, to save a little on A/C cost for a circulating indoor A/C system. Thereby drawing tremendous amounts of greasy and dusty air from the building through the projector. As we know NEC casings are not airtight, and enough air creeps through all slits into the machine, bypassing the filters, and leaving a residue of grease and fibers on all surfaces. Once burnt in, the glass surfaces are ruined, after cleaning it will never be reconditioned to the original condition.

Actually, when they are dismantled at Strong for cleaning, the glass parts are evaluated and if found to be bad then the owner of the projector has to buy a new light engine. That being said, I can't stress how important it is to use the NEC filters which themselves are actual Heppa filters. And further seal those filters to the openings by placing thin foam tape on the faces that seal against the cabinet. I have had NEC's in for going on 12 years in some locations and the prisms are still ok.

[Marco Giustini]

I still find enough setups, which use the 8" blower on the top and ventilate directly to the outside air, to save a little on A/C cost for a circulating indoor A/C system. Thereby drawing tremendous amounts of greasy and dusty air from the building through the projector. As we know NEC casings are not airtight, and enough air creeps through all slits into the machine, bypassing the filters, and leaving a residue of grease and fibers on all surfaces. Once burnt in, the glass surfaces are ruined, after cleaning it will never be reconditioned to the original condition.

What you said.

It is so sad to see the vast majority of installs extracting air from the projectors and then replacing the air with untreated air from outside.
I've done some maintenance in a few cinemas where the air was being recirculated in the booth - with an AC system in place of course - and the guts of the projectors were just spotless.

Indeed the disadvantage is that if the AC fails, the room would overheat soon. But at that point one could add an emergency extractor so fresh untreated air is pulled in until the AC is fixed.

The bottom line is that this is seldom accounted for. Or just dismissed. But the long term consequences are dear.

[Mark Gulbrandsen]

What you said.

It is so sad to see the vast majority of installs extracting air from the projectors and then replacing the air with untreated air from outside.
I've done some maintenance in a few cinemas where the air was being recirculated in the booth - with an AC system in place of course - and the guts of the projectors were just spotless.

Indeed the disadvantage is that if the AC fails, the room would overheat soon. But at that point one could add an emergency extractor so fresh untreated air is pulled in until the AC is fixed.

The bottom line is that this is seldom accounted for. Or just dismissed. But the long term consequences are dear.

It's very common in this country. I think they figure that the expense of a light engine now and then is a lot less than installing a system that cleans the air for the entire booth. But because of the pandemic, many chains have at least put in better filtering in the auditoriums. The problem I saw all the time was the popcorn popper not being exhausted out doors. Thus the hot air from the popper travels upwards and heads right up the booth stairs. Then the projector living at the top of the stair way gets contaminated with oil and grease. I have actually had Christie projectors dripping popcorn oil from the negative lamp support and the rear inside of the lamp house covered in popper oil.

[Frank Cox]

Maybe it's just the location and design of my building, but I have an exhaust fan that blows air outside from the projector and when the techs come to do the regular maintenance they usually tell me that the filters are still so clean that they barely need changing. (But they change them anyway, of course.)

[Dave Macaulay]

Yes the booth should have clean air. I don't have any authority to dictate to owners though. I told them the problem and showed them the filth inside the thing. There is an exhaust near the popcorn chimney: advised them to duct that into the exhaust. I think when laser systems with no exhaust go in the problem will be much reduced.
At minimum they have the 3k+ prism cleaning bill, or a 10k replacement prism, to get an acceptable image. Might get a message through.
i see super clean booths and nasty ones. If I can smell popcorn popping - in the booth - as soon as they start prepping for showtime I know the filters and fans will be greasy regardless of projector or server type. I have convinced some to vent the smoke and/or weatherstrip the booth door and keep it closed. Small town sites with the owner operating will usually listen to reason. If the operator rents the place and just runs it... the booth isn't the only thing neglected. The big chains are usually pretty good but weird things happen. The ex-AMC multis here (Canada) use the booth as the supply or return air duct for the 10 or so rooms in a wing. Not too greasy but lots of dust. New builds are nasty for months after opening with concrete dust, sealing the booth floors seems to be deleted when the schedule gets tight before opening ... the contractor feigns surprise when we show up a few weeks before openIng with truckloads of equipment to put up there - they have the move-in schedule FFS. Not unknown to have booth walls being painted and sprinklers hung with racks and projectors in place.

And to clarify: this is a very remote site. Right now one could walk or snowmobile south 750 miles to the closest mainland town with a road to civilization assuming the ocean is fully frozen over (probably not?). But no food or gas stations on the trip. Not super cold here now (it is spring after all) but above freezing ... maybe in mid May.

[Marco Giustini]

Mark, sometimes it doesn’t need any additional expenditure - or very little, just a beefier AC unit.

the AC is often installed anyways so it’s just a matter to make sure it can remove the heat generated by the equipment and the system is going to live on recirculated air.

what I found is that most people just fail to understand this basic concept. They feel that if the hot air is not extracted outdoor, the system is going to overheat regardless.

and also most people I met feel the AC ‘split’ units are injecting fresh air from outside - no they’re just treating the existing air. (It may work differently in the US of course)

[Randy Stankey]

Why wouldn't forced air exhaust with fans blowing on the hottest components, followed by a larger blower, extracting out of the room be better than fans just blowing hot air around in the room?

Do you need exhaust ducts in every installation? Not really but you should consider this in your plans.

I still think you should use exhaust ducts if you can.

[Mark Gulbrandsen]

At minimum they have the 3k+ prism cleaning bill, or a 10k replacement to buy.

Last time I needed a prism, we priced new and it was closer to 28k USD. We were lucky and got one from a brand new shipping damaged projector from MIT for around 15k. In my case it wasn't grease or oil, but damage from some building demolition right next door to the theater. When you have 100+ stuck or dead pixels it becomes obvious.

[Tony Bandiera Jr]

Last time I needed a prism, we priced new and it was closer to 28k USD. We were lucky and got one from a brand new shipping damaged projector from MIT for around 15k. In my case it wasn't grease or oil, but damage from some building demolition right next door to the theater. When you have 100+ stuck or dead pixels it becomes obvious.

Mark, I recall that thread and you replaced the light engine, not just a prism. And a prism won't have any stuck pixels. right?

LOL you crack me up when you shoot from the hip without thinking first.

[Mark Gulbrandsen]

Mark, I recall that thread and you replaced the light engine, not just a prism. And a prism won't have any stuck pixels. right?

LOL you crack me up when you shoot from the hip without thinking first.

Now where did I say the prism had stuck pixels??? "When you have 100+ stuck or dead pixels it becomes obvious."

[Marcel Birgelen]

Once the pixels start to get stuck to the prism, I'd call the Ghostbusters and call it a day.