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This topic comprises 2 pages: 1 2
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Author
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Topic: Problem with Dolby CP850 auto mute auto about 5-7 seconds
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Marcel Birgelen
Film God
Posts: 3357
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012
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posted 03-01-2019 03:09 AM
quote: Tony Bandiera Jr
Well that's gonna be kinda hard to do, running shows without sound to try to replicate an intermittent problem.
Why?
First off all, there is nothing in Nguyen's posts that indicates this is an intermittent or more importantly, hard to replicate problem, it might as well happen with each and every show or how likely it is that the problem occurs.
Secondly, if you're not sure what causes the problem, it's a good start to try to eliminate factors. If the problem still persists, even with the load of the amps disconnected, you know that you have to look elsewhere.
The CP850 does have log files, but they're pretty spammy. There is an on-line log-analyzer that's halfway useful located here.
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Tony Bandiera Jr
Film God
Posts: 3067
From: Moreland Idaho
Registered: Apr 2004
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posted 03-01-2019 07:30 PM
Why, Marcel?
Because he did not state that this is a consistent problem (even if it is, he also did not state that it is happening right at the start of a playlist, or say between trailers and the feature, or even at random points during the feature.)
Just because you had that instance of a bad amp affecting the CP650 does not mean that the same problem is happening in this case. (And you did not specify HOW it was affecting it...a simple shorted input won't do it, a shorted output definitely wouldn't do it..but an internal fault in the amp that either is feeding DC back up to the audio inputs or a fault causing the amp to draw too much power from (or generating noise spikes in) the incoming AC line COULD cause the CP650 to trigger odd formats or a mute command, happened to me once on a service call, it wasn't the AMP doing it, but an arcing connection in a rack receptacle.)
ANY microprocessor controlled unit is subject to odd behavior due to incoming power (which is why I had asked about a UPS), radiated noise (EMI or RF) getting into power, control, data or output lines. One theatre I serviced had problems with their two-way radios glitching the servers (first gen units) when they transmitted too close to the racks.
My point in saying what I said was two-fold: One, it is VERY unlikely, based on over 30 years experience, that what happened to you is the cause here (I have serviced well over a thousand screens in my career, many of them with Cp500, Cp650, Cp750 and the DTS processors) and have never had any issue with a failed or faulty amp causing the PROCESSOR to act up.
Two, you assume that he will have the downtime to test your theory, which he may well not have. And what if running with all of the amps off doesn't solve it? Now you have wasted all that time on something that has a very low probability of causing the issue. (Oh, and with ALL of the amps off, how do isolate the culprit? Do you guess, or do you then repeat the whole process turning on only one amp at a time and then waiting who knows how long to get a reaction?)
I am not saying in any way that what you suggest is IMPOSSIBLE, but I am saying that there are many other areas to be checked out FIRST, with a much higher probability of finding the cause. If and only if the other higher orders of possibility turn up nothing, then by all means I agree with giving your theory a try.
Stranger things have happened with audio and microprocessor-based gear...
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Marcel Birgelen
Film God
Posts: 3357
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012
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posted 03-04-2019 02:13 AM
All you do is give a rant, you're not helping to find a solution. You're just trying to prove your supposed superiority.
We actually own a CP850 and we know how flaky it can act, it's by far the least reliable audio processor Dolby has ever produced.
Now, without any more input from Nguyen Jack, we could guess for hours upon hours about what the potential problem could be. Is it an errant macro? A software bug? Or another external factor?
quote: Tony Bandiera Jr
Two, you assume that he will have the downtime to test your theory, which he may well not have.
Everybody has the downtime to do some simple tests, even if it's at night or early in the morning. But yes, he might run that one screen in the world that runs 24 hours, 365 days a week, no time to perform some tests for a few hours.
You act like you need to deconstruct the entire auditorium to run this test, while it's a simple thing to do. Simply switch off all the amps, which even in a fully featured ATMOS setup doesn't take more than a minute or two if you're really slow. But he might run this oddball auditorium, where the amps are behind the screen, in the basement and on the roof.
Getting back on the stability of the input power. The CP850 is essentially a Supermicro server with highly buffered PDUs. The thing keeps running for 5 seconds, even after you switch off the UPS it's connected to. There has to be quite some issue with your power supply, before it will affect this machine.
quote: Tony Bandiera Jr
Just because you had that instance of a bad amp affecting the CP650 does not mean that the same problem is happening in this case. (And you did not specify HOW it was affecting it...a simple shorted input won't do it, a shorted output definitely wouldn't do it..but an internal fault in the amp that either is feeding DC back up to the audio inputs or a fault causing the amp to draw too much power from (or generating noise spikes in) the incoming AC line COULD cause the CP650 to trigger odd formats or a mute command, happened to me once on a service call, it wasn't the AMP doing it, but an arcing connection in a rack receptacle.)
Yes, I had this particular problem happen, which caused something similar than his particular issue. So, that's why I bring it up as a possible source of his problem.
This particular amp had one of the two signal pins (don't know if it was + or -) of one of the inputs connected to the ground. Since it was a surround channel, it was not immediately clear.
quote: Tony Bandiera Jr
(Oh, and with ALL of the amps off, how do isolate the culprit? Do you guess, or do you then repeat the whole process turning on only one amp at a time and then waiting who knows how long to get a reaction?)
Besides just pissing around and yet again, trying to prove your superiority, I'm actually interested in what would be your, super-efficient solution to find the culprit in such a case?
quote: Tony Bandiera Jr
I am not saying in any way that what you suggest is IMPOSSIBLE, but I am saying that there are many other areas to be checked out FIRST, with a much higher probability of finding the cause. If and only if the other higher orders of possibility turn up nothing, then by all means I agree with giving your theory a try.
Since you know so well, tell us, what areas should be checked, which weren't already covered?
- Input power -> check
- Errant macros -> check
- Software update -> check
- EMI/RF interference -> mentioned at least twice now
- Log files -> mentioned at least 3 times
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Tony Bandiera Jr
Film God
Posts: 3067
From: Moreland Idaho
Registered: Apr 2004
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posted 03-04-2019 12:12 PM
quote: Nguyen Jack
Thanks for all support,
After update newest software 2.3.1 , i don't see problem.
I still follow it a few days.
You're welcome Nguyen. Hopefully the update solves the problem.
Marcel, the ONLY ONE ranting on here is YOU sir. You really need to rethink how you talk to people.
How many years of experience do YOU have servicing and building cinemas and sound systems? I started my career actually building projectors as well.
How many screens do you (or have you) serviced as a technician?
Have you ever done component level repairs on amplifiers, processors and other equipment?
I took the time to calmly state why I felt that the approach you suggested was least likely to be the root of the problem, you waste our time with a butthurt rant. Let me repost the last part of what I said to you so hopefully you can see how ridiculous your rant was: (to make it more clear I will bold the key points for you)
quote: me
I am not saying in any way that what you suggest is IMPOSSIBLE, but I am saying that there are many other areas to be checked out FIRST, with a much higher probability of finding the cause. If and only if the other higher orders of possibility turn up nothing, then by all means I agree with giving your theory a try.
Stranger things have happened with audio and microprocessor-based gear...
Now I never once tried to be "superior", this is not a contest of whose willy is bigger...I am stating some FACTS based on the long term experience I have in dealing with cinema sound, processing and control equipment.
So next time, don't take something so personally when it was very clear it was not a personal attack.
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Marcel Birgelen
Film God
Posts: 3357
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012
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posted 03-04-2019 02:04 PM
See, now you're ranting again. Yes, I was ranting in my post, but only after you had to show your proverbial penis length to me. And you can go all kinds of lengths to claim you didn't, but you even repeated it in your last post.
I'm not going to prove myself to you. Don't need to, don't want to. I've done sufficient digging in the dirt to know my routine. And yes, I've soldered a few things in my past, both repaired existing stuff and built new stuff from scratch... have programmed quite some stuff, so I know a bit about the inner workings of electronics. Still, I don't feel like a king now.
quote: Tony Bandiera Jr
I took the time to calmly state why I felt that the approach you suggested was least likely to be the root of the problem, you waste our time with a butthurt rant.
Again... I've never claimed it to be the likely the root of the problem. I've clearly stated: I've encountered a SIMILAR problem once before, which might be worth pursuing if the obvious (which was largely already covered) fails...
Also, you didn't answer my questions. Like:
quote: Tony Bandiera Jr
(Oh, and with ALL of the amps off, how do isolate the culprit? Do you guess, or do you then repeat the whole process turning on only one amp at a time and then waiting who knows how long to get a reaction?)
So, what is your magic solution in this case?
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Tony Bandiera Jr
Film God
Posts: 3067
From: Moreland Idaho
Registered: Apr 2004
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posted 03-09-2019 01:02 PM
quote: Sam D. Chavez
Tony, please give it a rest. You are starting to sound like Gulbrandsen on a bad day.
I am disappointed that this was all you wished to contribute to this discussion.
As the man who is most knowledgeable about all things Dolby, I would hope that you could elaborate on what YOU think might have caused the OP's problem.
For one thing, with your inside knowledge of Dolby equipment, can you explain WHY the bad amplifier in Marcel's case caused the CP-650 to behave as it did? And have you ever encountered the same situation? (Or another situation of any kind where a bad amp caused a PROCESSOR to malfunction?)
Marcel explained that "This particular amp had one of the two signal pins (don't know if it was + or -) of one of the inputs connected to the ground." I have had that happen on many occasions, both in cinema and in live sound, and the only thing that happened is I lost sound on that particular channel, never the entire processor (or mixer.)
You of all people Sam should know that flies in the face of good troubleshooting practices. For example, if your car starts misfiring, would you say "Oh, let's disconnect the drivetrain" (amps in this case) to see if that's why the engine (processor in this case) is misfiring?
I can't speak for anyone else, but I was always taught when troubleshooting you go from input to outputs, exhausting all possibilities at EACH stage before moving on to the next.
Again I repeat that I did not ever question that Marcel experienced that problem, nor was it an impossibility. But the method he explained of "shutting ALL of the amps down" makes no sense, as how do you isolate the culprit when you do something like that?
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Marcel Birgelen
Film God
Posts: 3357
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012
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posted 03-09-2019 05:48 PM
quote: Tony Bandiera Jr
Again I repeat that I did not ever question that Marcel experienced that problem, nor was it an impossibility. But the method he explained of "shutting ALL of the amps down" makes no sense, as how do you isolate the culprit when you do something like that?
Tony, in the end, efficient troubleshooting follows simple statistical logic...
While troubleshooting a problem, you first obviously apply your collective knowledge on it. If it's a known and/or obvious problem, well, you can get that one off your list easily...
Harder to debug issues are best tackled by elimination than doing a linear search through the entire possible "problem space" (which might be close to infinite), it speeds up stuff quadraticaly, if not more... Try to "halve" the problem, like Gordon called it. In my case, simply turning off the B-Chain would be such a step. Problem still there? Then it's not your B-Chain. Problem seems to be gone? Then you should investigate your B-Chain...
Depending on the complexity of the issue, you may iterate the "halving" multiple times, obviously.
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