Barco DP2K-20C: SPG prong fused to brass cup in lamphouse anode connector

[Leo Enticknap]

This is going to be a bit of a challenge:

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Went to do a planned maintenance call at a single screen independent yesterday, to include a lamp change. Problem: I could not pull the lamphouse module out after undoing the three screws. The cause turned out to be that the prong on the start pulse generator had fused totally and utterly solid to the brass cup in the anode connector on the lamphouse module. The owner told me that a few months ago, the projector was accidentally run for a day with the exhaust fan off. I also found the coolant level barely on the minimum mark and with a lot of goo deposited in the reservoir cap and neck, with says to me overheating and evaporation, and that the overheating also caused the two anode pieces to weld themselves together.

As you can see in the pic, I tried placing the blade of a large, flathead screwdriver where the two pieces meet and giving it a couple of moderate whacks with a hammer, with no luck. I didn't want to use more than minimal force, in case I accidentally caused damage that made the projector inoperable. There are around 60 hours left on the lamp warranty and it still works as of now, which gives me a little time to figure out how to fix this, along with awaiting the delivery of a replacement SPG and anode assembly.

The question is how to extract both the SPG and the lamphouse module from the projector, given that they are now a single unit, and an internal bulkhead prevents pulling them both out as one from either the card cage side or the light engine side. My thinking as of now is to remove the assembly containing the cold mirror and its fan. This should give me enough room to get in with a hacksaw or a Dremel, and cut through the fused piece.

I wondered if anyone has encountered this before, and if so, has figured out a somewhat less medieval way of liberating the stuck components?

[Steve Guttag]

And that's the one you CAN see. I have not had this happen to me (yet). My first thought is a cutoff wheel on a dremel...presuming that the cathode terminal isn't also fused. If you can take the back of the projector, i think you get a view of the side of the lamp house. If so, then you can remove the hardware on the anode terminal. With neither nut on it, the whole thing should pull through the nylon part.

[Miguel Moreno]

That happened to me with a 20C unit. What I had to do was unscrew the tip of the SPG because it was permanently stuck.
I took the tip from a broken SPG and had to buy the socket from Lamp House.

[Pete Naples]

I have used a long drift and a lump hammer before now.

Then replaced the offending DC connectors.

[Ryan Gallagher]

Not familiar with this procedure but just some machinist type thoughts throwing out there:

I don't know what your access looks like, but I'd be tempted to try some "freeze spray", and then maybe repeat your gentle whack method. Perhaps you could get the parts to shrink enough for the weld to become more brittle and crack?

Next up is Steve's suggestion of a precision tip on a dremmel, or a precision files perhaps attacking just the weld, gouge out a bit like you are doing a weld prep? But the cuttoff wheel could allow you to separate the two for sure (in a destructive way).

The exact model may vary, but this diagram of a similar barco SPG may be relevant.

SPG_example.png
via Strong: https://strong-tech.com/shop/project...ies-r7681046k/


Is it possible to get a wrench on the SPG prong hex flange to try turning the SPG prong itself, not the big nut, but the brass one integral to the prong itself relative to the cup? (Maybe they are not designed to turn in place, but the hex flange suggests maybe they do as part of their assembly procedure). That would seem to be where your leverage advantage is according to the diagram a similar barco SPG and it's prongs.

[Tj Hopland]

I have just gone the excessive force route and its always worked to get them apart. Its like something about the plating on the parts keeps from getting a clean weld. Its also possibly that I was just lucky and mine were further gone to the point where much of the material had burnt up.

Any way you go about it at this point you will need the SPG and socket set. IF you had a pile of parts you could maybe take the SPG pin off a failed for another reason SPG but when I have seen them get that stuck you can usually see that the SPG had got pretty hot internally so you know its life will likely be shorter. I believe all 3 (S,C & B) there is to some degree a cast metal bulkhead between the lamphouse module and the SPG so you really don't have a lot of access other than what Leo pictured.

Any of the xenon Barcos you can get it where someone doesn't get the anode cable of the lamp properly torqued so it heats up and expands which then increases the resistance which then increases the heat till something gives. I think what causes this on the C projectors is at some point someone slid the socket assembly into the internal heat shield instead of the outer case where its supposed to be.

The heat shield is further back plus not really well supported so you barely get any pin engagement. If you are running a 1200 you can kinda get away with it, 4000 not so much. If its a smaller lamp it will usually come apart fine because it really wasn't engaged but the tip of the pin will be all pitted. I think its when you then put it back together the proper way and jam that pitted pin into the socket the pitting damaged the surfaces in the socket so you get back to the whole resistance heat race happening. S and B's didn't have that shield.

[Frank Cox]

the projector was accidentally run for a day with the exhaust fan off. I also found the coolant level barely on the minimum mark and with a lot of goo deposited in the reservoir cap and neck, with says to me overheating and evaporation,

Barcos don't have overheat sensors?

[Ryan Gallagher]

Barcos don't have overheat sensors?

Or airflow sensors? I know my christie will refuse to strike if my exhaust is not on... though never tried turning the exhaust off while running.

[Steve Guttag]

Barco has plenty of temp sensors and if they go out of range, the lamp won't stay lit or be allowed to light. The B series has air flow sensors but they are warning type only. Christie's air flow sensors are part of their downfall. They false trip far more than they help anyone. This was true in the film days too. It is nuts that they continued them into the digital era in that they used industrial switches designed to switch 120V with some current behind them. Their contact material is not designed for the low-current circuits of a Cinema projector. On top of that, they didn't protect them, at first (and then charged one for the UV kits). When they do false trip, they won't re-strike the lamp. "Unexpected Lamp Off" errors drive me absolutely nuts with Christie projectors. With the new Cine-Life + RGB laser projectors, hopefully, that is in the past.

[Tj Hopland]

edit: Steve beat me to it, I basically said the same thing......

The B's have a 'sail switch' and they all have temp sensors but they are fairly forgiving and will give you a yellow tail light warning. It takes quite a bit to get to the red possible shut off level. If you have the bigger model in the family running a smaller lamp I have seen them not even trip the yellow warning. If you are running the max lamp size they will go yellow fairly quick but may not go past that depending on what the rest of the setup is. A short vertical run with no dampers may just keep going but a long horizontal setup and gravity or motor dampers that close its going to back things up worse.

Those keep going characteristics can be both good and bad. It can be a good thing that they will just keep running compared to some of the other brands where any temp or fan speed falls out of normal you are looking at a minimum a reboot or possibly even off screen till parts are replaced. Some machines a fan speed is 1 rpm below normal you are done even if temps are fine so there is no turning down the booth AC and pointing a external fan at it. Bad part is if no one notices the warnings in person or remotely things could just cook for days to years.

[Frank Cox]

Barco has plenty of temp sensors and if they go out of range, the lamp won't stay lit or be allowed to light.

Based on this thread, the sensors they do have don't actually work.

There's always a trade-off between a false alarm and no alarm but it seems like they've pushed the balance too far in the wrong direction. At least in the case of this individual projector.

"Sorry your house burned down; your sleep wasn't disturbed by a false smoke alarm and that's a good thing, right?"

[Leo Enticknap]

Thanks everyone.

We're going to need to wait for the SPG and receiving cup assembly to be ordered and shipped, so the next update on this won't be a while, but I will post one when the time comes. The site is also quite remote and a few hours' drive to get to, so I think, taking Steve's point, that I'm going to bring another cathode adapter, too, just in case the overheating fused that one as well. This is the first time I've had to deal with a stuck anode, but I have encountered a stuck cathode adapter before.

With the cold mirror fan assembly out of the way, I think my first line of attack will be to try to get a wrench onto the SPG pin and unscrew it, as Miguel suggests. If that doesn't work, the next step will be the hacksaw or Dremel, depending on what there is room for.

Agreed with all points on the way Barco manages overheating. Christie goes to one extreme (shuts the lamp off at the first sign of vane switch trouble, and makes you wait 10 minutes before letting you start it again), NEC is kinda in the middle (nasty bleep that forces you to take action, but gives you the ability to take that action before show interruptions), and Barco is at the other extreme (won't shut the lamp off until the lamphouse gets to 95% Celsius, by which time the projector has likely melted into a blob of plastic and aluminum).

[Oleg Batiaiev]

There was such a situation. It was solved by completely removing the cold mirror assembly together with the cooler, this gave full access to the UF glass mount of the lamphouse, it can be removed after these manipulations. Then bite off the anode cable of the lamp and you can pull it out so as not to break it. Then unscrew the anode contact from the SPG and dismantle the SPG itself. I think you will figure it out further.

[Dave Macaulay]

Had this a few times, from the site staff changing a lamp and putting the anode DC connector on the inside lamphouse sheet metal rather than on the outside where it belongs That gives a poor connection as the pin just enters the socket. The connector welds itself together. Can't remove the lamphouse, can't do much anything except curse.
I think we had to buy a new connector kit for the lamphouse (including several parts not needed but that's the Barco way) and a new SPG (the pin part not available separately). Now after some laser conversions, we have a few spare connectors and SPGs at least.
Some disassembly required to get a hacksaw blade at the pin.
I have taken pliers to the inside sheet metal on many lamphouses, bending it in so the connector can't be slid onto it.

[Leo Enticknap]

Thanks everyone. Parts are ordered, but the SPG is on back order from Belgium, and so there likely won't be an update very soon.