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Author Topic: CP-750 power supply issues Stephan Shelley Jedi Master Film Handler Posts: 854 From: castro valley, CA, usa Registered: Nov 2014 posted 07-27-2016 07:48 PM                     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.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 07-28-2016 06:51 AM                     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).  |  IP: Logged Adrian Avram Film Handler Posts: 45 From: Iasi, Romania Registered: Oct 2013 posted 07-29-2016 11:36 AM                     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.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 07-29-2016 12:45 PM                     The DMA8 Plus uses the same supply too!  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 07-29-2016 06:50 PM                     Chuckle! Every tech I know has been there...  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 08-12-2016 10:51 AM                     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.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 08-12-2016 12:41 PM                     It is 100% functional.  |  IP: Logged System Notices Forum Watchdog / Soup Nazi Posts: 215 Registered: Apr 2004 posted 06-01-2018 09:07 AM                 It has been 657 days since the last post.  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 06-01-2018 09:07 AM                     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?  |  IP: Logged Adrian Avram Film Handler Posts: 45 From: Iasi, Romania Registered: Oct 2013 posted 06-01-2018 02:50 PM                     Hi, You can search for Dolby Field Bulletin 262 which describes the problem in details.  |  IP: Logged

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