my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » CP500 Output Distortion and Panel Meter Glitches (Page 1)

This topic comprises 2 pages: 1  2

Author Topic: CP500 Output Distortion and Panel Meter Glitches Tom Ostertag Film Handler Posts: 41 From: St. Louis, MO, USA Registered: Jun 2014 posted 09-03-2016 10:28 PM                     Hi all, My CP500 has developed an odd intermittent problem. Occasionally one channel of audio output will sound distorted after power-up. This sounds like it's happening in the digital domain, almost as if it's missing one or more bits of precision, very similar to a "bit crusher" effect. The issue is present with any input selected. The first time I heard the issue it was in my front left channel, and most recently it happened in the right surround. In both cases, power-cycling the processor solves the problem. To make matters worse, when I power-cycled the processor after the last occurrence of this issue, my front panel meters started showing periodic high level spikes on the Rs and SW channels (even with a silent source), while the outputs sounded fine with no clicks/pops/distortion. While passing audio, the meters also started frequently freezing for several seconds at a time before updating again. This processor has always had some sort of "phantom level" on the SW meter since I acquired it, but this is much worse. I'd have to verify, but I think I'm on the latest software revision. Also, the clock stability modification has already been performed from the factory. Has anyone else noticed instability in these areas? Should I start looking at capacitors, or any specific boards? Component-level troubleshooting and repairs are not foreign to me, but any ideas on where to start would be much appreciated! —Tom  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 09-05-2016 11:08 AM                     Hi Tom The vu meters freezing and the vu meters spiking with no sound is something I've seen before and AFAIK it's a known issue and you don't have to worry about that. Please make sure you are on the latest SW which is 1.65. Regarding the distortion, that is a known issue too but I am not sure whether it's ever been solved or not. The 500 had tons of known issues - some of those could be fixed by reworking, others by replacing components, others by replacing boards. I cannot honestly remember if the distortion issue was a fixable one, I'm sure others will be more helpful than me on this subject!  |  IP: Logged Sean McKinnon Phenomenal Film Handler Posts: 1712 From: Peabody Massachusetts Registered: Sep 2000 posted 09-05-2016 04:21 PM                        I'm just curious how long you've had this CP500 and if it was working without this distortion and display issues at one point?  |  IP: Logged Tom Ostertag Film Handler Posts: 41 From: St. Louis, MO, USA Registered: Jun 2014 posted 09-06-2016 12:50 AM                     Thanks for the info so far. I've had this processor for probably a little less than a year. I got it off eBay, so its history is unknown. I've added the Cat 885 6-channel ADC and 683 crossover cards to suit my application in my home screening room, and also replaced the 5V 1F "super capacitor" on the Cat 984, which was physically leaking a bit. Apart from that, the components and PCBs look pristine. There has always been some noise in the VU meter for the SW channel, with the meter randomly rising and falling without any signal I/O. I mentioned that to one of my friends, and he didn't seem at all surprised, so I figured it was a common and harmless issue. Since it got worse around the last occurence of audible distortion, I thought there might be some correlation. I've been a victim of troubleshooting coincidence enough times to know better though, so I realize they may not be related. Since I've had the processor, and I use it a few times a week at least, I've heard audible distortion as I described only twice. Probably a couple few apart, with the most recent one being last Tuesday. In both cases, a power cycle eliminated the symptoms. Signal flow would suggest the source of the distortion is either the Cat 675A DSP that's used for equalization, or the 684 that's telling it what to be and do. Of course the components look flawless, but I haven't tested any electrolytic capacitors yet. This may just be one of those little issues that has no reasonable explanation. I work in broadcast television, and we have broadcast-quality HD video monitors that occasionally crash and have to be rebooted. Monitors! The days of digital device problems surprising me are long gone. Well after all that, I just powered up my CP500 to check the software version, and I'm on 1.61. I thought for sure I was on 1.65. That's a real glaring issue right there! More to follow when I get the thing updated, hopefully later this week.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 09-06-2016 03:41 AM                     Hi, Get rid of 1.61 ASAP, that's evil The subwoofer VU meter spiking at random is definitely "normal", I'm confident it's not related to the distortion you have heard. I love the CP500 but it's not the best product made by Dolby. I'll see if I can find what was causing the distortion and see if there was supposed to be a solution.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 09-06-2016 02:41 PM                     Hahaha! I'll never forget the CP-500 firmware version that caused the 500 to factory default. I was told by reliable sources at Dolby that it was written in the code to do this after so many power cycles by a disgruntled Dolby Employee. I think it was 1.28 or 1.32, or 1.46 or something like that. Dolby really pissed off a lot of new customers with that issue. Mark  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 09-06-2016 03:12 PM                        What format is selected when you have this problem? We had a similar issue in a 6-plex, but only in SRD. Switching to an optical format (and leaving it there) or rebooting fixed it. We never actually resolved this one, but it stopped happening when we stopped moving the SRD cards around from processor to processor (they had six screens. SRD readers in every projector, and six CP500s, but only three sets of SRD cards). The theory at the time was that it may have been a backplane issue. They were also running version 1.61 firmware, as it happens. If I remember correctly, this only happened on the first show of the day (when it did happen, which was only occasionally).  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 09-06-2016 04:10 PM                     I experienced that too and my 500's were running 1.61 too. Mark:  |  IP: Logged Tom Ostertag Film Handler Posts: 41 From: St. Louis, MO, USA Registered: Jun 2014 posted 09-07-2016 01:53 AM                     quote: Scott Norwood What format is selected when you have this problem? We had a similar issue in a 6-plex, but only in SRD. Switching to an optical format (and leaving it there) or rebooting fixed it. When it does happen, it's on that output/speaker channel, no matter what the input is. You can switch around between external 6-channel, nonsync, SR, etc, and it's there. I don't have a Dolby Digital penthouse yet, so I don't know about SRD. Interesting that you had distortion somewhere else, and reboots fixed it. Well, I finished the upgrade to 1.65 tonight. Super easy with Load500 v2. The hardest part was lugging the XP desktop with the real serial ports upstairs! So far so good! I rebooted the CP500 a couple times, and haven't seen bad meter readings yet. No distortion yet either. Only time will tell if that was all it needed! I was skimming through my last post, and realized I called the Cat 685 an 885, and the 684 a 984. That's what I get for late-night typing. Oh well, I'm sure y'all knew what I meant. I'll be doing some more screenings soon, so I'll keep an eye and ear on things closely and report my findings!  |  IP: Logged Frank Bolkovac Film Handler Posts: 27 From: Monroeville, Pa. USA Registered: Mar 2011 posted 09-07-2016 11:48 AM                     Mine did the same with no effect on the sound. Some spiked, some didn't. Four different multi-plexes. All 500 processors. If your getting distortion from time to time, it might be coming from someplace else. Lots to check after or before the processor.  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 09-07-2016 12:50 PM                     quote: Well, I finished the upgrade to 1.65 tonight. Super easy with Load500 v2. The hardest part was lugging the XP desktop with the real serial ports upstairs! A Keyspan USB-to-RS232 adapter has never given me the slightest bit of trouble. I've used them on multiple laptops running both XP and Windows 7. https://www.amazon.com/s/?ie=UTF8&keywords=tripp-lite+keyspan+usa-19hs&tag=googhydr-20&index=aps&hvadid=78443082048&hvpos=1t2&hvnetw=g&hvrand=14416756660006450799&hvpone=&hvptwo=&hvqmt=b&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1013962&hvtargid=kwd-75246 206808&ref=pd_sl_5vdlri4ehb_b  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 09-07-2016 04:17 PM                     Frank, The noise coming from some of the speakers was a known issue with the 500's. Probably your processors were not affected (it may be that there was something that could be done to remove the issue) but if someone reports of distorted sound which fixes itself with a reboot, it's most likely the 500 itself! I have found a reference to an EFB 188 regarding improper noise and tones but unfortunately my notes do not specify what the EFB 188 is!  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 09-07-2016 04:51 PM                        Don't forget the small jumper wire from case ground to low side of an output. Kinda not in all manuals.  |  IP: Logged Tom Ostertag Film Handler Posts: 41 From: St. Louis, MO, USA Registered: Jun 2014 posted 09-08-2016 12:32 AM                     quote: if someone reports of distorted sound which fixes itself with a reboot, it's most likely the 500 itself! Agreed! I've most certainly narrowed it down to the processor. I have some audio distribution amps in another frame, and a patch panel, but the reboots and my booth monitor rule out those things. The distortion was verified to be present immediately after the CP500, and not before. And the CP500 was the only device I rebooted to clear the issue. Well, the amps were powered down too for safety, but the booth monitor shows the distortion before the amps. quote: Louis Bornwasser Don't forget the small jumper wire from case ground to low side of an output. Kinda not in all manuals. Indeed, the chassis–signal ground jumper is in place on the CP500, and the CP500 is used as the central ground for all line-level devices. Not a ground loop in sight! I ran a movie through it tonight (via external 6-channel in this case), and I didn't have any audio issues. Also tried some non-sync sources with the same result. However, the phantom meter levels came back, so that looks like a minor annoyance I'll be stuck with. I expected that, after all the reports of that being normal for others. As long as it's nothing in the audio! More monitoring to come.  |  IP: Logged Tom Ostertag Film Handler Posts: 41 From: St. Louis, MO, USA Registered: Jun 2014 posted 09-23-2016 07:46 PM                     The audio distortion problem just happened again, this time in the center channel. So updating the software version wasn't the cause, though I am happy to be on 1.65 now. Since the issue happens on power up, I'm going to try turning on and off the CP500 with its power/bypass button, rather than the rack power distribution. Maybe the electrical noise from starting the other line-level equipment at the same time was causing problems. I always turn the power amps on after the Dolby/DTS/booth monitoring gear, so there shouldn't be any major power ripple from those. We'll see!  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 2 pages: 1  2

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.