Prism contamination

[Leo Enticknap]

I can't provide any more detail as to where and from whom I heard that there was a hardware revision in progress to the TI DMD chips used in the SP4K .98" light engines, as I don't have permission to do so: all I can say is that I have no reason to disbelieve or doubt it.

There definitely has been a hardware revision to the light engine. As we're all aware, the first ones were also susceptible to convergence drift, a situation that was exacerbated by the fact that when swapping them out, it was physically possible to route the hoses such that one of them applied pressure to the edge of one of the formatter boards, thereby making it impossible to converge (although even with the hoses routed correctly, the convergence would still drift, though in many cases an adjustment after around 200 hours from new was all that was needed: it would stay put after that). Cinionic provided a cheat sheet with photos showing the correct and incorrect hose routing. Around the back end of last year, I swapped out one (I can't remember if the issue was dead pixels, convergence drift, or both), and noticed that the replacement had thinner hoses than those on the original light engine (the difference was clearly visible when the hoses were attached to those on the other side of the quick release couplings), and that one of them was slightly shorter, making it physically impossible to route incorrectly, such that it pushes down on the edge of the board. Every SP4K .98" LE I've installed since has had this new coolant hose arrangement, and I haven't seen or been told of any convergence drift problem with a "new hose" LE after installation and initial adjustment.

[Steve Guttag]

Marcel, you again try to use a different DMD that used the same similar technology to somehow make a generalization on the the specific 4K TRP problem as witnessed in the industry. Nobody was disputing that the TRP DMD originated when you state. The 4K DMD, as used by digital cinema (which is the only variant that matters in this forum), uniquely has shown a problem to this industry. I'll tell you what; why don't you ask the projector manufacturers if you don't have a direct link to TI if TI is working on a redesign of the 4K TRP (in the .98" size, to be more specific) to address mirror stick and report back to us. Otherwise, what you present is speculation, with respect to this problem.

Onto the prism. Yes I pulled it to see if I could field-clean it. The liquid issue was quite evident since it wasn't just on the inside of the assembly. As one could imagine, before it got in, it was already on the outside too and migrating. I went as far as I was willing to go, given the conditions of the situation. I cleaned what I could but I didn't want to take that screen down by getting into a situation where I couldn't, at least, keep it was in (do no harm). I recommend to the client to proceed with an RX prism.

[Marcel Birgelen]

Marcel, so you offer speculation on the light engine design and if TI is or is not working on a re-design? How about I heard 1st hand and leave your speculations out of it. Have they really been making 4K TRP DMDs since 2013? I doubt it but that is speculation on my part. In speaking to multiple DLP manufacturers, the TRP chips indeed have a higher rate of stuck pixels though not as high as what has been experienced by the 4K ones used in cinema machines.

The first TRP DMDs hit the market around 2013 in the form of pico modules (for micro projectors). That was their first broad application. The redesign of the mirror allowed them to shrink the DMD so it made sense for micro-projection applications. That's no speculation, but something that's easy to look up. Also, you see that TRP made it slowly into the 4K designs, to allow for smaller DMD designs, yet achieving 4K resolution. That's also no speculation, but a trend that can be easily seen across the differerent cross-market DLP offerings.

And if you read my post correctly, I'm not saying that TI is not working on a redesign. I frankly don't know and don't offer any speculation on that part and if I did, it was probably covered by some NDA. I'm clearly stating: I'm not aware of TI shipping a redesigned version of their TRP-based TI DLP chips. So, if TI is working on a redesign, it looks like those DMDs didn't make it out yet, or I must have missed something.

And if anything else changed, that change must have been part of the light engine and AFAIK, nothing changed there either. And that part was more of a question than speculation.

And yes, I've have, 1st hand pulled a prism and was able to see the contamination though if one gets down to the DLP part, you better have a lot of time on your hands or a jig to get them in alignment because it gets to the bottom DMD, the one you can't adjust while the prism is in the machine. This is something that Strong, that does have the facilities, can pull/clean and realign. Plus, one can get a fully cleaned prism assembly rather than a hack job in the field. Again, with a enough time, I'm sure it can be done in the field but I've seen one of these being realigned it can get rough pretty quick.

Well, that's kind of the reason why I'm asking. I clearly don't have the facilities and aren't qualified to align a prism, yet you pulled it out. I guess the intentions were to put it back in? If you make the efforts to pull it out, you know you're going to have to realign it anyway. So that's why I asked if you considered to clean it and if it's even feasible to clean it in the field.

[Steve Guttag]

Marcel, so you offer speculation on the light engine design and if TI is or is not working on a re-design? How about I heard 1st hand and leave your speculations out of it. Have they really been making 4K TRP DMDs since 2013? I doubt it but that is speculation on my part. In speaking to multiple DLP manufacturers, the TRP chips indeed have a higher rate of stuck pixels though not as high as what has been experienced by the 4K ones used in cinema machines.

And yes, I've have, 1st hand pulled a prism and was able to see the contamination though if one gets down to the DLP part, you better have a lot of time on your hands or a jig to get them in alignment because it gets to the bottom DMD, the one you can't adjust while the prism is in the machine. This is something that Strong, that does have the facilities, can pull/clean and realign. Plus, one can get a fully cleaned prism assembly rather than a hack job in the field. Again, with a enough time, I'm sure it can be done in the field but I've seen one of these being realigned it can get rough pretty quick.

[Marcel Birgelen]

Tilt-Rotate DLP chips have been around since 2013-ish, but have previously been used primarily in smaller, lower power assemblies. I'm not aware of TI having updated their design, but I may have missed that. The DCI DLP chips aren't available for the general market and as such, not all updates are published to the public by TI.

If nothing changed at the TI end, it has to be the light engine design itself. Since the increased pixel failure rate is probably due to cooling issues, that would indicate a redesign of the light engine, which, afaik, also didn't happen yet.

In general, I'd always go for the bigger chip size if given the choice, even if the costs are a more bulky light path and a more bulky machine. While there are lots of little differences between DLP chip designs, bigger mirror almost always means more contrast...

Mike's theater was previously able to fit at least one 35mm projector in the booth, so I doubt fitting this machine in there should be a problem. Only getting those things up there to those old theater booths often is quite a challenge. Those booths clearly weren't designed for regular large equipment swaps.

I will go out on a limb here and say it is definitely contamination as I have seen that exact same thing before and I pulled the prism and got down to where I could even see the liquid (seriously, it comes through the filter and that fan right above the prism is what is pumping the strained liquid contaminated air into the prism. The migration may seem like it is moving fast but remember, that prism is only .98" on the diagonal and we are being shown the 2.39 portion or the middle 3/4s or so. The magnification is so great, a little movement will seem like a lot. This also happened over a long time for it to make it this far but it is in there.

You've seen the contamination first hand, as you actually pulled the prism. There were no means to get the contamination off of the prism via any low-tech solution without damaging it beyond repair?

[Steve Guttag]

Darin, I cannot speak for Cinionic but I would suspect that they would not replace the light engine without a stuck pixels. For one, that would deprive those that have a stuck pixel from getting a replacement sooner. For singles (and really up to 5-plexes), definitely get the extended warranty. The money is just in your favor with the light engine, or ICP-D/ICMP...etc. Around 5-screens, the money starts to favor buying your own repair parts and getting light engines repaired.

Remember too, Cinionic includes standard overnight shipping (1-way) with their warranties.

I do not believe Leo's comments are correct on the state of the TRP chips, I do not believe that Barco (or anyone else) is shipping a redesign version yet.

The "C" and "B" series will continue to be a reference now that there are three overlapping versions. There Is an SP4K-15C and and SP4K-15B (likewise for the 20 and 25).

[Darin Steffl]

So if someone has an SP4K-12 built within the last 6 months with the original light engine, would Barco swap to the updated version for free before there's a problem? Or would they wait for stuck pixels and then replace for free if it's within warranty?

My other question is for a single screen theater, is it recommended to buy the extended warranty for this unit because of the high cost of replacement parts? Would the cost of the warranty be less than the cost of parts in a 10 year time period, for example?

[Leo Enticknap]

SP4K-40

SP4K-55

The full range of Series 4 models can be seen here. What might have been confusing you is that in all territories except China, the model number does not have the B, C, or S suffix: it's just SPXK-[integer; references output in lumens]. But many techs still tend to refer to them with the suffixes, to be clear in our minds what form factor we're dealing with.

From the SP4K-27HC up, the 4K machines have the 1.38" DMDs.

As for the .98" DMDs, I'm told that TI has redesigned them, and that Barco is now shipping light engines with the new design, that is nothing like as susceptible to pixels sticking as the old one. I would suggest that anyone contemplating buying an SP4K-C (i.e. an SP4K-XX where XX is 25 or below) writes in to the sales contract with their dealer/integrator that either it has the new light engine in it, or that one will be installed at no extra cost as soon as it becomes available.

[Darin Steffl]

Where can I find more info on the B series? Their website shows nothing about that nor does it reference C series. It's just the regular SP4K-x model numbers with the 0.98"

[Steve Guttag]

I will go out on a limb here and say it is definitely contamination as I have seen that exact same thing before and I pulled the prism and got down to where I could even see the liquid (seriously, it comes through the filter and that fan right above the prism is what is pumping the strained liquid contaminated air into the prism. The migration may seem like it is moving fast but remember, that prism is only .98" on the diagonal and we are being shown the 2.39 portion or the middle 3/4s or so. The magnification is so great, a little movement will seem like a lot. This also happened over a long time for it to make it this far but it is in there.

An advantage of the "B" series of the SP4K-15 is that it is on the 1.38" DMDs so the stuck pixel issue of the TRP DMDs won't be there (they can still stick but at "traditional" amounts). Be forewarned, the "B" Barcos in the SP4K are HUGE...so plan accordingly (seriously, with the lesn, it will be over 5-feet long). In the drawing below, I'm also depicting the optional exhaust adapters/dust covers. I use them as dust/spill covers. If one has exhaust, you can vent to the outdoors. However, they ship with the 8" (200mm) flange plugged so they can be used as dust/spill protectors. the top of the projectors have a rather porus grill for ventilation right above laser drivers and other heat producers. It is all too easy for something to come into the top of the unit. Installation of the adapters/covers does not interfere with the speed at which one can get into the unit for service. The feet location match up with their legacy DPxK-B series projectors:

SP4K-B.jpg

[Marcel Birgelen]

I think that picture wise, the SP4K-15B would be a great upgrade. The only downside is that you can't keep your Dolby 3D setup. Still, there are active shutter glasses now that are both dishwasher safe and pretty comfortable to wear and imho, they do give the best 3D out there, especially if you have a sufficiently bright picture.

The machine also comes also with "double marquee value": Laser AND 4K. (Although like stated earlier, the marquee value of 4K may be limited.)
So, I hope you can make it work somehow, without breaking the bank.

Such a progression of that issue in just 8 days... I am wondering if that is actually contamination or something else - a failed DMD I guess. I struggle to believe that contaminants can affect the picture so quickly.

Like I indicated before, I've seen something similar once before. It was in a Christie machine that was brand new. It also had a faulty prism: in this case, the prism itself was disintegrating. The prism in your average DCI projector isn't a single piece of glass, but a composition of multiple pieces of coated glass that are bonded together. I don't know how they bond them together, but I suspect it will be some kind of epoxy. In this case, there was a production flaw that allowed those pieces to slowly separate. This caused a reddish hue all over the image, much like what Mike is currently experiencing. It progressed pretty fast, from just a small corner up to the entire image in a matter of a month or so. After that, the prism was replaced and everything was fine again.

This is all speculation on my part, but I could imagine that if they use some kind of epoxy or "glue", that prolonged exposure to heat, UV light, etc. could cause it to let loose over time. That's why this is an interesting case and it's a fairly old machine by DCI standards. With a sample rate of just one, it's certainly premature to raise any panic, but it could be a sign of things to come for projectors of similar vintage, if this is what I think it is.

[Marco Giustini]

Such a progression of that issue in just 8 days... I am wondering if that is actually contamination or something else - a failed DMD I guess. I struggle to believe that contaminants can affect the picture so quickly.

[Mike Blakesley]

One thing you have to keep in mind if you're going to switch over to laser or any new machine is the lead times on new equipment. You really need to check this with your local integrator.

Our tech is keeping track of a few models. We are looking at the Barco SP4K-15B at the moment. Apparently they are actually in stock. But replacing the light engine is also on the table, if the grant thing proves to take too long. I just hate to spend that kind of money on a 13 year old unit that might have something else go wrong in the short term.

[Marcel Birgelen]

Yeah, it's really bummer if something like this happens. But when does equipment fail exactly at the right time?

If it's progressing this fast, I do think it's more a case of prism disintegration than a case of prism surface contamination. Not that this diagnosis is in anyway helpful to get rid of the problem, but it may be a sign of things to come to other projectors with the same prism assembly and of equal vintage.

As for the color calibration emergency hack Leo is suggesting: I think the problem here is the unequal way this issue presents itself over the frame. If you fix it for one spot, it will be completely off in another.

One thing you have to keep in mind if you're going to switch over to laser or any new machine is the lead times on new equipment. You really need to check this with your local integrator. Unless they have to happen exactly your model and lens on stock, it's not like you order today and have it tomorrow, especially in the current state of the world, were the supply chain seems to be constantly broken somewhere.

As for rental options: It's hard to compare prices between here and your place, but judging on the DCI equipment rental prices that are common around here, it's probably cheaper to get a repair of your current unit than paying for a rental unit for months on end, depending on how long you have to wait for the paperwork to be finished and having the new machine delivered and installed.

[Leo Enticknap]

The gotcha there is that the cost of shipping and installation (plus the same in reverse at the end of the rental) to a relatively remote location in rural Montana would be likely, I would guess, to at least double the price of the rental. If Mike feels comfortable installing it himself, that would reduce the overheads significantly, though. I'm wondering if it would be possible to tweak the color calibration to offset the prism discoloration a bit, as an emergency short-term measure. You'd need a photoradiometer, though.