Film-Tech Forum ARCHIVE: Film is Flickering

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Posted by Raymond Christie (Member # 4080) on 04-21-2007, 02:40 PM:

This just started today. We are running a print of Blades of Glory and it is flickering almost like a strobe. What do I do?

Posted by Mike Blakesley (Member # 26) on 04-21-2007, 03:41 PM:

If it's a steady flicker and the picture looks dim in general, you probably have a diode out in your lamphouse power supply (or in your console). What kind of lamphouse is it?

Posted by Chris Slycord (Member # 4239) on 04-21-2007, 03:44 PM:

It could be lots of stuff. Call your tech.

Posted by Monte L Fullmer (Member # 2797) on 04-22-2007, 02:21 AM:

chek this thread that someone else had with basically the same problem of light flickering problems.

And, you can do a search on the same topic as well, for this is one of the most common discussions that comes up from time to time.

Posted by Frank Dubrois (Member # 3042) on 04-22-2007, 02:46 AM:

Its usually one of two things. The projector needs to be retimed, or, as said before, its a diode. If its a very obvious stobe, kind of slow strobing, then its a diode. If its a very quick flickering type strobing, then its more likely a timing issue. What kind of projectors?

Posted by Monte L Fullmer (Member # 2797) on 04-22-2007, 09:18 PM:

quote: Frank Dubrois
If its a very quick flickering type strobing, then its more likely a timing issue

..which is commonly called 'ghosting' .. and he didn't mention anything on image streaking ...

About only way a picture would start 'ghosting' is if the shutter drive belt (being with a Christie P35GPS unit) has lost a few teeth and jumped time.

Posted by Mike Blakesley (Member # 26) on 04-22-2007, 10:40 PM:

I'd bet a year's worth of tickets that it's a diode.

' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' < some apostrophes for Frank.

Posted by Frank Dubrois (Member # 3042) on 04-22-2007, 11:48 PM:

quote:
' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' < some apostrophes for Frank.

Thanks but I dont use em all that much. If your gonna be watching my spelling too, then we have two people on this site that needs a hobby. As long as I dont mangle words and I am able to make my meaning clear, I consider any sentence structure, including spelling, a great success. Thanks for the apostrophes, I know right where to put em.

Posted by Aaron Sisemore (Member # 145) on 04-23-2007, 12:10 AM:

Before you tear into the power supply, check to make sure you are getting voltage on all three phases of the AC coming into the power supply... A missing phase will cause the exact same symptom as an open diode.

-Aaron

Posted by Michael Coate (Member # 757) on 04-23-2007, 12:41 AM:

quote: Frank Dubrois
As long as I dont mangle words and I am able to make my meaning clear, I consider any sentence structure, including spelling, a great success.

Your approach is why I have little respect for you. It's lazy...and disrespectful to everyone who uses their time to read your posts.

Posted by Frank Dubrois (Member # 3042) on 04-23-2007, 01:55 AM:

quote: Michael Coate
Your approach is why I have little respect for you. It's lazy...and disrespectful to everyone who uses their time to read your posts.

I really don't care what you think of me. So piss off.

quote: Aaron Sisemore
Before you tear into the power supply, check to make sure you are getting voltage on all three phases of the AC coming into the power supply... A missing phase will cause the exact same symptom as an open diode.

I might have to do that too. How? I've never checked that. The amount of flicker I get looks like a slightly mis-timed shutter or an old weak bulb. Is checking the phases posted somewhere in the manual (Christies)? Or can you easily explain the proceedure?

Posted by Phil Ranucci (Member # 3820) on 04-23-2007, 02:40 AM:

Use a meter and measure the input voltage to your rectifier where it comes in from the circuit breaker panel. You should have ~115 volts each hot to neutral and ~208 between any 2 hots if 3 phase or ~220 between the 2 hots in single phase.As you're poking into AC circuits be careful or get your tech to do it.

Posted by Kenneth Wuepper (Member # 1174) on 04-23-2007, 06:18 AM:

Most meters for incoming power to the building have either phase lamps, if they are the old analog type meters, or they have an LCD panel with the phases indicated on the face. You don't need to open any panels or make any meter readings to determine a missing phase if it is caused by the power company losing a connection in the net.

If it is within your building that the phase is lost, that is a service problem for your electrical maintenance person.

Do not remove panel covers from power sources unless you are qualified and authorized to do so. Do not work on power circuits without someone else present in case of an accident.

KEN

Posted by Monte L Fullmer (Member # 2797) on 04-24-2007, 03:42 AM:

Most common thing when a phase is lost is the triple pole 40amp breaker has one breaker that has gone bad and the breaker sometimes trips.

While the breaker is on, put your hand across the triple 40amp that are tied together with the common trip handle. If one of those breakers is HOT, you've got a weak breaker that needs replacing. For triples do go without tripping.

That is when you head to the main power room, find the panel that controls that subpanel in the booth, dump the power to that panel then you can swap out that bad breaker for the new one..

quote: Frank Dubrois
I know right where to put em.

(...forgot to put one of those apostrophes that Mike gave you before "em" .. "Tag, you're IT"..lol .. and don't leave yourself WIDE open with this comment of yours.. [Big Grin]

)