This is topic CP-750 power supply issues in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.
To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=16;t=002764
Posted by Stephan Shelley (Member # 8587) on 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.
Posted by Steve Guttag (Member # 268) on 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).
Posted by Adrian Avram (Member # 7931) on 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.
Posted by Steve Guttag (Member # 268) on 07-29-2016, 12:45 PM:
The DMA8 Plus uses the same supply too!
Posted by Mark Gulbrandsen (Member # 72) on 07-29-2016, 06:50 PM:
Chuckle! Every tech I know has been there...
Posted by Ken Lackner (Member # 1002) on 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.
Posted by Steve Guttag (Member # 268) on 08-12-2016, 12:41 PM:
It is 100% functional.
Posted by System Notices (Member # 2357) on 06-01-2018, 09:07 AM:
It has been 657 days since the last post.
Posted by Ken Lackner (Member # 1002) on 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.