Film-Tech Forum ARCHIVE: Random Sound Outage...Again

This is topic Random Sound Outage...Again in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Martin McCaffery (Member # 37) on 03-06-2011, 01:19 PM:

I don't think this is related to the previous random sound outages from last Fall. Those were channel outages, this is complete fail on one projector. I suspect the pre-amp power for machine is going bad. Looking for confirmation or other tests

Dolby CP-650, Kelmar power supply and red readers, 2 projector, hour reels. New LEDs (installed in October).

Feature is analog SR

Friday night first show ran fine.

Second show the analog policy strips at the end of the trailer reel on Proj 2 fail. No one noticed at the time as they are only two strips with music.

First half of the show on Proj 1 runs fine. About 30 mins into the reel on Proj 2, complete sound drop out (I was already gone, projectionist called when it was back running). By the time the projectionist hit buttons etc, sound was back. No further problem.

Sat afternoon I come in and run loops for awhile while working on other things. Cannot force a fail.

Saturday evening, first show trailers and policy strips run fine. Proj 1 is fine. 3mins into Proj 2 sound fails. Does not come back within a minute or two so we switch to other machine. Runs fine.

Second show, policy trailers fail. Proj 1 fine. Proj 2 fails about 3 mins in again. Swith machines.

Sunday morning, I come in to test Proj 2. Trailers and policy strips run fine. Feature reel has sound for about 3mins then fails. I let it run and try hitting the changeover, clicking throug formats etc. Did not try by-pass mode or check the signal present lights in front panel. The pre-amp light on the power supply was noticeably dimmer than the others though it was the same as the others when it started. I turn off the machine and let it alone for ten minutes. I start it again and the sound is fine and runs for the next 50 mins without problem. Tried running a loop for a few minutes after the reel and still could not force a fail.

Anything I should test before ordering a new power supply for the analog? I've not had any problems with the digital sound, though, of course, the only digital we're running this week is the trailers.

Posted by Louis Bornwasser (Member # 3063) on 03-06-2011, 07:55 PM:

If you are there when sound is lost, look to see if the "preamp" led on the side of the power supply is dim or out. If not on, SMACK IT. You will probably restore sound. (bad board inside box,) Louis

Posted by Martin McCaffery (Member # 37) on 03-06-2011, 09:24 PM:

That worked.