Barco DP2K-20C light pipe temp high

[Marcel Birgelen]

Did they try to flush the light engine with a syringe and failed at doing so? If so, the clog might be too severe to flush out. I'm not sure if those heatsinks are serviceable or if they're welded shut, as I've never opened one up. Barco usually doesn't sell them separately either, but you can find some of them from salvaged light engines.

[Mark Gulbrandsen]

Nope, they don't leave the filters out (I've had ICP fan failures too). NEC's perscribed fan replacement interval is 20,000 hours. You have posted that you change them all. Okay...fair enough. And, on the NC1200/2000 we are not talking about a huge number though the current cost of the fans is getting near the cooling pump price but you'll change those fans out a couple of times before the cooling pump...if you go at NEC's recommended times. On our NEC systems, we power all of the way down to shut off the AC-On fan too so it does not prematurely age.

Nope, I don't change them all. Just the Power On, AC On and ICP fans... at 5 year intervals. Those are thee three critical fans in the 1200 and 2000 projectors. I have had no reason to change any of the other fans. And as I mentioned before, another Tech I know in the Northwest had an exhaust blower fail in an NC-2000. Had only two ICP failures, one in a Drive in that was struck by lightening and one in a very early NC-2000 when I was changing the battery. NEC was pretty sure the super capacitor in that one was defective. Otherwise, they just chug right along. In the broadcast industry we generally also never just changed out fans unless one died or became noisy. And I would follow suit with the rest of the fans in any NEC.. The transmitter got serviced once a week during the 6 hours of down time on Sunday night. But every Sunday we serviced a different part of the transmitter.

[Leo Enticknap]

I don't know what is meant by "tear the cooling system apart," but if the reservoir > pump > radiator section of the cooling circuit flushes without any resistance, there is no blockage there and it can be left alone. Next step would be to take the light engine out of the projector, then isolate each of the three DMD heatsinks in turn, and try to push coolant through them using a syringe. Even if the blockage creates too much resistance to push coolant through the entire light engine in one go, I'd be very surprised if the coagulated coolant is bad enough to prevent any at all from going through just one of the DMDs. But if it is, take a large sewing needle (or a recessed reset button poker, if you have one), and try to poke it through the barb coupling entrance at either end. I have had to do this once, and managed to unblock the light engine to the point at which I could flush the rest of the crud out with the syringe.

If this is what's happened, I'd be willing to bet that someone has used green or red automotive coolant in the projector at some point, and/or fully concentrated coolant without diluting it, or they diluted it with tap water rather than distilled.

[Marcel Birgelen]

If you're using the green/blue coolant specially made for IT cooling systems instead of the "Barco approved" stuff, you should be fine, as the same stuff is also used in high-end servers, gaming rigs and other IT applications and the modern iterations of those coolants/additives are mostly fine, as in, if properly mixed, they leave little to no residue. Mixing the orange/red stuff with the blue stuff is asking for lots of troubles, it almost works like a gelling agent...

Using non-distilled water can be a problem, mostly due to the calcium contents in the water. Calcium tends to settle in hotter regions, creating lime deposits that also tend to attract other gunk. I'm not sure about the general availability of distilled water around the globe, but around here it can be had for under a Euro a liter, so there is no real need to skimp on that one.

[Andrew Thomas]

From what I've been told, these units were serviced by Film-Tech (most recently in January of 2020), so I'm doubting they were cheaping out on the coolant.

As far as what the MIT tech said, I believe they indeed were able to push coolant through the radiator but couldn't get anything pushed through the output side of the DMD heatsinks.

[Randy Stankey]

...Using non-distilled water can be a problem, mostly due to the calcium contents in the water...

Reverse osmosis filtered and deionized water.

At the plating shop where I worked, DI was used for virtually everything. Most of the plating baths (hundreds or even thousands of gallons) used DI water to make them up. All of our lab tests used DI, exclusively.

At the electronics shop where I work, any time a part is cleaned, it is done with DI water then followed with 99.9% isopropyl alcohol to absorb and evaporate the water. Then, the parts are baked at 125 deg. C for 30-60 minutes in order to get all the moisture out.

Sure, there might be differences but, for technical and laboratory purposes, RO/DI is the thing to use.

Getting it might be a problem. To make DI water, you need to have a water purification system. That would be expensive unless you use a lot of it.

In such a case, it might be easier and cheaper to buy steam distilled water from the store.

[Leo Enticknap]

We have a five-stage under-the-kitchen-sink water filter system at home, that includes a RO filter stage. It can't deionize, obviously. The water that comes out of it tastes a darn sight better than unprocessed from the faucet, but the filter system doesn't get all the crud out - it still leaves a little residue, e.g. on the cats' water bowls, or in the bottom of the dehumidifier. For applications where totally clean is needed (e.g. in a liquid cooling system, or for my record cleaning machine), distilled is the only option. As it only costs around $2.50 for a (US) gallon (a little under four liters) and can be bought at any supermarket, it's no big deal, given the amount of it I go through. It was more of an issue when I lived in England though: there, I could only find it at hardware/DIY stores, and it cost 2-3 times as much as it does here.

[Mark Gulbrandsen]

When I worked in Broadcast back in the late 70's, we made deionized water for the transmitter cooling loop, which in itself was quite large for a 100KW transmitter. The crew before me put in a special 2 stage still that made the deionized water... it always ran and never broke down... drained into a large 55 gallon plastic drum. We never had any clogs or problems other than the crappy solder job on the joints in the piping that was originally done by RCA when the transmitter was installed. Since there was never enough down time, being on the air almost 24/7, and only having 6 hours early Monday am to do maintenance, we could not re-do all the joints in one fell swoop. We had to wait and fix each joint as they sprung a leak. In this transmitter you put water in and got steam back out of each of the three klystrons. A condenser up on the roof turned the steam back to water again.

[Marcel Birgelen]

I guess for a plate shop, using anything other than DI water will end up in misery, like contaminated end products and possibly some nasty gasses too...

I still have a professional, small scale DI rig, but no longer use it. We used it to make distilled water for the skincare my wife used to make, but eventually it was cheaper and less of a hassle to buy it in bulk than to make it yourself, considering the time and efforts you need to put into it. I don't know what the deal is with England and distilled water... It's no longer part of the EU, but maybe I should start a DI-water export business.

Regarding those RO home filter systems: I guess you really want those minerals to be left in there, at least to some extend. You won't die from drinking a few glasses of distilled water, but if you don't replenish those minerals with the rest of your diet, you end up with a lack of electrolytes in your body, which can have quite severe consequences. I guess most Western diets include sufficient sodium and other minerals though, that drinking DI water doesn't really matter, but if you're on a diet, stuff may look differently.

As for using residue heat from cooling systems to distill water: Not a bad thing and green thinking all the way back in the late 70s.
I guess the problem is that you need to find a heat source that's hot enough to actually boil the water or else you still need to put extra energy into the system to get there, but if you get steam out of it, then I guess you've found your perfect source. I don't know how efficient a 1970s era 100 kW transmitter was, but since transmitters are usually rated by their output and not their electrical input, I can imagine there was quite a bunch of heat coming off that cooling system to work with.

[Randy Stankey]

To build a plating bath, you clean and strip the tank with DI and acid, scrub it and rinse it with clear DI. You put in new filters then fill the tank 1/3 with DI and technical grade acid. Usually 96% sulfuric, except when the bath contains cyanide. Instead, you use Rochelle Salt. Mixing acid and cyanide would be bad.

Then you add metal salts, depending on the metal you are plating. Copper sulfate for copper plating, nickel or tin sulfate respectively, etc. If you are plating gold or silver, it’s gold or silver cyanide.

Then you have to give it time (minutes to hours) for the metals to complex. After that, you add the secret sauce…brightening agents or restrainers to control the quality of the final result. Top it off with more DI then dummy plate for up to 12 hrs. in order to build up free metal ions.

This is where the DI comes in. If there are stray ions of iron, calcium or other things, THEY will plate instead and really ruin your day. If that happens, you’ll have to scrap the bath, strip the tank and start all over again. If you scrap 200 gallons of liquid gold cyanide, you’ll find yourself standing in the boss’s office within the hour.

To make DI, there was a large reverse osmosis filter, about the size of a refrigerator which fed into a pair of ion exchange resin cylinders. The processed water is then stored in a 1000 gal. tank for distribution through the plant.

That’s a lot of time, trouble and expense that only makes sense in an environment like a plating shop. If you only need a gallon or two, it would be stupid to do all that. Even in the electronics shop, they only use a small DI machine, about the size of a 55 gal. drum, which would still be too much.

Probably better to buy distilled from the store.

Occasionally, I “borrowed” some RO/DI from work to use in my darkroom at home.

Still, even with that job perk, I still found it easier to buy water fro Walmart.

[Gordon McLeod]

Do not used deionised distilled water as the water will activily attack the metals of of the unit
Every Imax person knows about pump rebuilds

[Randy Stankey]

Are you saying that, because of the lack of dissolved substances in the water, it will tend to leach metal in its surroundings?

That's counter intuitive but I guess it makes sense. I'll have to read up on this.