Film-Tech Forum ARCHIVE: Christie Interlock error, lamp won't light (but no actual interlock open)

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Posted by Steve Guttag (Member # 268) on 06-26-2019, 09:35 PM:

So I'm seeing a trend here with Christie. TWICE on the same day but at different locations, I had systems go down with a mysterious "Interlock error, lamp turned off for safety"

There were no interlocks open (and none were specified). Power cycling the system brought it back up without further incident. One projector was a CP4220 and the other a CP4230. Both are running current software 4.8.1.

This is on top of a recent spat of "Unexpected Lamp Offs" where one can restrike but it may or may not stay lit (normally it stays lit). I only get unexpected lamp offs from Christie and Christie refuses to set up a mode where if the lamp was on prior to an unexpected off, it won't try to restrike on its own. Christie would rather people sit in the dark and miss the movie due to their own equipment error. With no interlock open there is no reason to not restrike. If after say 5 tries it won't restrike...okay...bad lamp but enough with ruining shows!

Posted by David Gibbons (Member # 10887) on 06-26-2019, 09:48 PM:

i have recently had something like this happen at one of my locations . lamp would shut off but not give me an error. turned out to be a belt on the exhaust system on the roof was loose and needed to be replaced

Posted by Stephan Shelley (Member # 8587) on 06-26-2019, 10:33 PM:

Did you check the fire alarm jumper or connection? It is considered an interlock as well.

Posted by Marco Giustini (Member # 4544) on 06-27-2019, 05:44 AM:

I'm sure you know this already - I see all the interlock lines are going through the Ballast - then back to the backplane. Reseating those connectors (both on the ballast and J9/P9 on the backplane) may help. Failing that, it could be a faulty switch, faulty ballast, faulty cable, faulty backplane, faulty PIB or just software bug!

IF the software highlighted WHICH ONE of the switch triggered the interlock alarm, it'd be easier! [Smile]

Posted by Steve Guttag (Member # 268) on 06-27-2019, 06:38 AM:

I think it is just bad design, period. Again, only Christie does this crap and this sort of thing messes up shows. The fact that it won't restrike on its own makes it all the worse. Once the interlock clears, restrike! For unexpected lampoffs, restrike up to five times (or three if your are more nervous).

As for an exhaust fan, then show an extractor fan interlock error in conjunction with the lamp off. And, in the case of an extractor fan, configure your software for a bobble delay...running the lamp an extra 5 seconds with low exhaust isn't going to change the safety outcome but will dramatically change the performance outcome. I can understand an immediate shutoff for a lamp door interlock. That really IS a safety thing but once that door closes and the switch is satisfied, it should go back on if that was the mode immediately prior to the interlock breach. Switches get noisy (especially without cadmium in them) but again, stop punishing the audience.

Posted by Carsten Kurz (Member # 5396) on 06-27-2019, 07:34 AM:

A colleague was suspecting that aging switches will become a problem with many projectors sooner or later. I think Harold also mentioned the issue of detection loops offering not enough wetting current for these contact materials.

- Carsten

Posted by Marco Giustini (Member # 4544) on 06-27-2019, 07:49 AM:

I agree with you, Steve, 100%. I believe - not totally sure - that the interlock switches are talking to the Ballast which in turns talks to the software. I reckon this is to switch the lamp off even though the software has crashed.

I guess this is why a delay is not an easy fix as it's not the main software's responsibility. But as you say, running the lamp with low extraction for 5-10 more seconds is not going to hurt anybody. In fact, you could show a "insufficient extract warning" before shutting off everything.

Posted by Stephan Shelley (Member # 8587) on 06-27-2019, 12:00 PM:

I have had to replace a few of the airflow switches. They do go bad. They are basically the same thing Christie used with their 35mm lamps and consoles.

Posted by Jim Cassedy (Member # 4115) on 06-27-2019, 12:31 PM:

I was about to mention the air flow switches when Stephen's message
popped and beat me to it. That being said, I too have run into several
flakey air flow switches on Christie DCP projectors in the past couple of
years, and on one of their film consoles I was working with too.

Posted by Mark Gulbrandsen (Member # 72) on 06-27-2019, 02:06 PM:

If Christie is still using that shit stack switch it should always be suspect first. Swithes today are absolute crap because there is no cadmium in the contacts. After checking that, check the exhaust system. I had a location in Wyoming that occasionally had such strong winds that it blew back down the stack just enough... against an 780 CFM blower and shut the stack switch off. Use a temp seonsor Christie like the rest of the world does.

Mark

Posted by Steve Guttag (Member # 268) on 06-27-2019, 02:13 PM:

Christie has a temp sensor on the exhaust too. They just don't bobble delay that stupid sail switch (or any of their interlocks but particularly the sail switch. They also don't seem to be capable of noting if a lamp goes out on its own to try and restrike it.

Posted by Stephan Shelley (Member # 8587) on 06-27-2019, 03:52 PM:

On a similar note has anyone else noticed that as these machines age it becomes more necessary to reseat boards and connectors. I have had intermittent ballast com errors and have had to reseat the Dsub connectors at the lamp ballast and the backplane connector. The reseating seems to polish the connections and the problems go away.

Posted by Carsten Kurz (Member # 5396) on 06-27-2019, 04:16 PM:

At least for the ICMP, Barco has a Techbulletin that recommends cleaning of edge contacts during C Maintenance. I guess not every machine suffers the same, but...

- Carsten

Posted by Marco Giustini (Member # 4544) on 06-27-2019, 04:23 PM:

I have used dry contact cleaner before on connectors but I was always concerned of removing some sort of oxidation protection as well - which may show up at a later stage.

I believe there is a recommended product from Barco though which costs an arm and a leg - probably for a reason.

Posted by Steve Guttag (Member # 268) on 06-27-2019, 09:11 PM:

Seriously, who has the time to try and reseat the dsubs on the CP2220/4220? They don't give enough room to fit a normal sized hand in there! One thing Barco really creamed the others on is the serviceability of their projectors. Everything is on the "outside" of the projector so you don't have to "dig in" or remove a bunch of stuff to get at what you need.

That said, Barco seems to have found the most unreliable connectors they could for the signal backplane on the signal backplanes. The reseat requirements are probably 10:1 of the other two OEMs. Signal Backplane failures (when reseats no longer last more than a week) are at least 10:1 and probably 100:1 of the other OEMs (I haven't had to change an NEC or Christie signal backplane but I'm up to at least a dozen Barco backplanes on their B and C series projectors). I don't doubt that the Middle-Atlantic area and our humidity have an effect on contact oxidation since we always had problems with tin plated connectors compared to gold plated.