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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » CP-750 power supply issues

   
Author Topic: CP-750 power supply issues
Stephan Shelley
Jedi Master Film Handler

Posts: 675
From: castro valley, CA, usa
Registered: Nov 2014


 - posted 07-27-2016 07:48 PM      Profile for Stephan Shelley   Email Stephan Shelley   Send New Private Message       Edit/Delete Post 
There has been much written here about the 750 having power supply issues but I haven't seen discussion of what the issues are other than they have them. My question is do they just fail all at once or do they stumble around causing the sound to cut in and out? Trying to find a possible cause of sound cutting in and out on a screen. Was fine the next day and today when I was there checking things out.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12134
From: Annapolis, MD
Registered: Dec 1999


 - posted 07-28-2016 06:51 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
I recall talking to someone at Dolby about it and they "claimed" it was merely a bad run of power supplies. The run was large so many, many units were affected. There was something about a component out of tolerance that allowed it to fail. One thing we put in our specs is, at least, one back up supply per complex (since it is plug-in anyway).

I have not experienced the cut in/out thing (yet).

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Adrian Avram
Film Handler

Posts: 37
From: Iasi, Romania
Registered: Oct 2013


 - posted 07-29-2016 11:36 AM      Profile for Adrian Avram   Email Adrian Avram   Send New Private Message       Edit/Delete Post 
I had many CP750 power supplies that went bad, but I was able to fix them all. Every single one had a blown varistor on the mains input area, failed open, so the affected processor looks dead. The quick fix was to disconnect the mains cable and use the external supply. Replacing the affected part has "resurrect" them all, some are more than three years now in service.
Just a quick tip, the CP750 and the DFC100 3D filter controller use the same PS.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12134
From: Annapolis, MD
Registered: Dec 1999


 - posted 07-29-2016 12:45 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
The DMA8 Plus uses the same supply too!

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16151
From: Bountiful, Utah
Registered: Jun 99


 - posted 07-29-2016 06:50 PM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
Chuckle! Every tech I know has been there...

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Ken Lackner
Phenomenal Film Handler

Posts: 1876
From: Atlanta, GA, USA
Registered: Sep 2001


 - posted 08-12-2016 10:51 AM      Profile for Ken Lackner   Email Ken Lackner   Send New Private Message       Edit/Delete Post 
What functionality does the processor have when running on backup power? Is it a limited "bypass" function like USL's JSD line of processors? In searching through the CP-750 installation manual, I can only find information stating that a backup supply exists, but no mention of processor functionality.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12134
From: Annapolis, MD
Registered: Dec 1999


 - posted 08-12-2016 12:41 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
It is 100% functional.

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System Notices
Forum Watchdog / Soup Nazi

Posts: 215

Registered: Apr 2004


 - posted 06-01-2018 09:07 AM      Profile for System Notices         Edit/Delete Post 

It has been 657 days since the last post.


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Ken Lackner
Phenomenal Film Handler

Posts: 1876
From: Atlanta, GA, USA
Registered: Sep 2001


 - posted 06-01-2018 09:07 AM      Profile for Ken Lackner   Email Ken Lackner   Send New Private Message       Edit/Delete Post 
I had a CP-750 die yesterday. Replaced the main power supply with one pulled from a DFC100. All good.

quote: Adrian Avram
I had many CP750 power supplies that went bad, but I was able to fix them all. Every single one had a blown varistor on the mains input area, failed open, so the affected processor looks dead.
How can I identify which component is the culprit, and do you have a vendor and part number for the replacement?

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Adrian Avram
Film Handler

Posts: 37
From: Iasi, Romania
Registered: Oct 2013


 - posted 06-01-2018 02:50 PM      Profile for Adrian Avram   Email Adrian Avram   Send New Private Message       Edit/Delete Post 
Hi,
You can search for Dolby Field Bulletin 262 which describes the problem in details.

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