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Author Topic: CP650 sound "wow" on changeovers running Dolby Digital... Jim Henk Master Film Handler Posts: 364 From: San Diego, CA Registered: Feb 2006 posted 10-27-2011 04:23 AM                     Just curious... what's going on at a UCI screening room that downtime is so hard to come by?  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 10-27-2011 05:30 AM                    Here's another test that you could try during your downtime which might give interesting results... With projector #1 running and projector #2 threaded with a blank leader, or loop, or whatever, start the motor on projector #2 while you're in the middle of the reel on #1. Then after #2 ramps up to speed and the wow stops (assuming the wow also happens while you're in the middle of the reel), shut down #2. What happens?  |  IP: Logged Ian Parfrey Phenomenal Film Handler Posts: 1049 From: Imbil Australia 26 deg 27' 42.66" S 152 deg 42' 23.40" E Registered: Feb 2009 posted 10-27-2011 06:03 AM                     Why does this sound like really badly regulated mains going to the projector motor? What does a cro show when hanging off the motor supply on the incoming machine?  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 10-27-2011 09:19 AM                        Tony: can you swap the 773s? You would then have an iron-clad idea of exactly what is wrong. Working on room; how about after midnight. That is my way out at the local Univerisyt. Louis  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 10-27-2011 02:56 PM                     Jim: Both rooms are used for classes during the day. BTW, if you are available I can use a second set of eyes for the process. Mark: That is one of my planned tests. Ian: My tach display shows no speed variations during these events. Note that the problem is happening on the machine that is already running at speed when the incoming machine is ramping up. And what the heck is a "CRO"? (These are also inverter drive motors that are pretty immune to mains issues unless the voltage becomes extremely low.) Louis: The plan is to swap the 773's first, the 774's second and if that doesn't work I will have to have Dolby swap the entire processor. Midnight access is harder to get than weekend for some odd reason...University policies are very odd sometimes. And I don't fancy staying up all night for this. Thanks for all the tips and advice guys..I'll let you know how it all shakes out.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 10-27-2011 03:11 PM                       Is the Davis loop on the outgoing projector's reader doing anything strange like jumping up and down during this event? What is upstream of the reader, just an upper reel spindle with a passive clutch for hold back tension?  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 10-27-2011 03:48 PM                        I like Sam's first idea on his first post. Sometimes the most unreasonable thing is it, even though it is still unreasonable. Louis  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 10-27-2011 07:36 PM                     Sam: To your questions, no and yes. I can see the possibility for the reel spindles to be a cause, if it it wasn't happening with such consistency on both machines, and if it weren't for the fact that the last reel can play all the way to the end with no issues. (And this isn't an irregular variation, it is a smooth ramp-up to speed kind of thing.) (For the thread title, "wow" was the best thing I could think of that would fit the title line limits.) I'll know late Saturday afternoon what's up for sure. However, it is something that will be looked at during my test.  |  IP: Logged Ian Parfrey Phenomenal Film Handler Posts: 1049 From: Imbil Australia 26 deg 27' 42.66" S 152 deg 42' 23.40" E Registered: Feb 2009 posted 10-27-2011 08:06 PM                     Tony. CRO = Cathode Ray Oscilloscope or 'scope for short. I feel very old all of a sudden.  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 11-01-2011 02:33 PM                     Ian: No need to feel old mate..I think it was just a difference in Anglo-Aussie terminology. Ok gang, here's the outcome of the testing on Saturday: Problem persisted at the startup of a reel, but was consistent ONLY when starting at the very beginning of a reel. If I ran partway into a reel, stopped, then did a "changeover" running up from a point other than the leader, the problem would happen.... sometimes. Doing a changeover into the start of a reel with the Digital reader's LED off, no variation of the outgoing reels speed. All relays for Motor Start and P1/P2 select were working normally. No speed issues with either projector. The other room was in use so I could not swap cards. Dolby is sending me a CAT 773 and CAT 774 to swap out to see if it solves the problem. I did find that my power supply voltages were a bit low (big surprise..not) but Norm says that the values I came up with should not be an issue. Both room's PS read about the same. I will be picking up a CP-650 for my own room here shortly, configured the same way, so I will not only have a reference point but also have service spares. (And no, I will not be selling my CP-65 unless someone makes an offer I can't refuse.) So I will be doing another test this coming Saturday, if I can get the room again and hopefully the problem will be fixed.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 11-01-2011 07:14 PM                       Tony, What kind of leader did you have on the incoming reel? Did it have SR.D info on the perfs? That might explain why no variations in speed when making a changeover in mid reel as there is most likely SR.D info unless you are using film from the stone age.  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 11-01-2011 10:43 PM                     Sam, all reels leaders are print originals and have the data starting at the usual location. My hunch is that the start of a reel has no data, then the data starts being read before the actual changeover and that is why the clock picks up on it. During a mid-reel run up data is present immediately and I think the processor's clock ignores it (treating it like a dropout and reversion perhaps?) The other interesting thing is that forcing reversions on either machine while running behaved perfectly normally. Isn't modern electronics fun?  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 11-02-2011 05:10 PM                     Tony, have you been using the same print for this? Do you observe this problem with other prints? Could the condition of the print be an issue? The heads/tails of repertory prints are so often trashed. What are the error rates at the head, midway and tails? In all honesty, I wouldn't guess that could cause "wow" but who knows? You seem to have stumbled into uncharted territory with this one. To quote General Beringer from "WarGames": quote: "Hell! I'd piss on a sparkplug if I thought it'd do any good." Do I understand correctly that you have tried starting with BOTH reels at a midway point (that is not "wow-ing") and executing a changeover from there? In other words, what happens when you perform a changeover with "known-working" data blocks incoming/outgoing?  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 11-02-2011 05:38 PM                     Manny: This has happened with several prints, some of which are brand new and have error rates of 3 or lower. So print condition is not a factor. My test print runs at 4-5 and it does the same thing. Yes I tried mid reel changeovers from my test print and as I posted, sometimes it would act up and sometimes it won't. I got the replacement cards from Dolby today and have the room for testing again on Saturday so once I isolate which card I'll report back.  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 11-02-2011 06:13 PM                     Make sure you rip out all of those little blue bits. They only get in the way! Sorry. Couldn't resist. Old Film-Tech humor. Disregard.  |  IP: Logged

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