Film-Tech Forum ARCHIVE: Problem with Dolby CP850 auto mute auto about 5-7 seconds

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Posted by Nguyen Jack (Member # 7530) on 02-24-2019, 10:50 PM:

Hi everyone,

I get problem with Dolby CP850, the Cp850 auto mute all channel about 5 - 7 seconds then unmute.
Everyone can help and let me know solution to check and fix it.
It is using with Christie IMB.
Version software: 2.1.0
Thanks.

Posted by Marco Giustini (Member # 4544) on 02-25-2019, 04:29 AM:

Hello,

How do you know it is thew 850 muting the channels and not something else on the chain? Do you see the MUTE button flashing red on the front panel?

Posted by Nguyen Jack (Member # 7530) on 02-25-2019, 04:38 AM:

Hi Marco,

Hello,

I see the MUTE button flashing red on the front panel.

Posted by Harold Hallikainen (Member # 5405) on 02-25-2019, 09:28 AM:

OK, that's strange! Is the CP850 just playing AES/EBU audio, or Atmos, or something else? Under what circumstances does it do this? Is the CP850 connected to Ethernet so it could get automation commands? I don't remember if the CP850 has logging, but if so, it would be interesting to know what the log says.

Good luck!

Harold

Posted by Tony Bandiera Jr (Member # 2365) on 02-25-2019, 10:13 AM:

Is the CP 850, AND IMS powered thru a UPS?

A momentary power glitch (even one not long enough to interrupt playback or make the projector lamp go out) could cause this problem.

If the equipment is on a UPS, when was the last time the battery was changed?

(Troubleshooting 101, start with the simple things first.)

Posted by Marco Giustini (Member # 4544) on 02-25-2019, 12:34 PM:

I think you should consider have the logs inspected. If the mute button engages, something will be logged in the logs.

Posted by Nguyen Jack (Member # 7530) on 02-25-2019, 08:51 PM:

Hi Tony,

All equipment on UPS. CP850 and Christie IMB installed on November 2016.

Posted by Marcel Birgelen (Member # 6801) on 02-26-2019, 08:01 AM:

Does this happen on all shows?

And how is the CP850 hooked up to the IMB?

How are you sending macros? Over IP or over serial?
Is there anything connected to the CP850 GPIO?

Posted by Nguyen Jack (Member # 7530) on 02-27-2019, 03:59 AM:

Hi Marcel,

CP850 connect with IMB over IP, use IP for send marco.
Don't using GPIO on CP850

Posted by Marcel Birgelen (Member # 6801) on 02-27-2019, 07:43 AM:

Did you check your server logs it's not inadvertently sending a MUTE cue to your audio processor?

I've seen something similar on a CP650, which would sometimes seemingly randomly switch into mute on all channels. In this case, it was caused by a bad amplifier, which apparently triggered some self-preservation mechanism in the audio processor.

Posted by Nguyen Jack (Member # 7530) on 02-27-2019, 10:30 PM:

Hi Marcel,

The logs file don't see mute cue, I upgraded new software 2.3.1 lastday.
Hope will be fix the problem.

Posted by Marco Giustini (Member # 4544) on 02-28-2019, 04:17 AM:

Did you find anything else in the logs? As the MUTE button engages, I'd expect to see something in the logs to be honest - such as something crashing or similar.

Posted by Marcel Birgelen (Member # 6801) on 02-28-2019, 04:37 AM:

Well, if the update doesn't fix the problem, try to run it with all amplifiers switched off. Just to make sure it's not the same issue I've once encountered with a CP650.

Posted by Harold Hallikainen (Member # 5405) on 02-28-2019, 10:14 AM:

Does the CP850 have a log? If so, it would be interesting to see what's there. Also, is this a new problem on an existing installation, or is it a new installation? Finally, I had a problem with some JSD-100 units muting on loud audio near Las Vegas NV. Looking at Google Maps, I found the problem was worst in the auditoriums that were closest to a cell tower. Going to the site, I tried disconnecting various connections from the JSD-100. It turned out that the problem went away when I disconnected the HI/VI audio cable. At that time, the JSD-100 HI/VI audio went to some ADC inputs on the microcontroller to measure the HI/VI audio output levels. When there was loud audio (including on HI), the RF combined with the audio to force ESD protection diodes in the microcontroller into conduction. This "scrambled" I/O making it look like the mute button was being pushed. In the field, I added series resistor in each of these audio lines at the JSD. Since the input impedance of the IR panel is high, this did not affect the audio. It did, however, drop the RF voltage conducted into the JSD. We then made a hardware and software change in the JSD. We improved the EMI filtering on the HI/VI outputs. We also removed the link back to the microcontroller ADC inputs and, instead, measure the HI/VI levels in the DSP. The JSD-100 measures audio levels (for the front panel bar graph) on the analog audio outputs on the rear panel. The JSD-60, designed later, reduced cost by measuring all audio levels in the DSP.

So, long story short, is it possible an RF signal is getting into the CP850? Is the problem reproducilbe? Can stuff be disconnected and make the problem go away?

Good luck!

Harold

Posted by Tony Bandiera Jr (Member # 2365) on 03-01-2019, 01:57 AM:

quote: Marcel Birgelen
Well, if the update doesn't fix the problem, try to run it with all amplifiers switched off. Just to make sure it's not the same issue I've once encountered with a CP650.

Well that's gonna be kinda hard to do, running shows without sound to try to replicate an intermittent problem. [Roll Eyes]

Posted by Marcel Birgelen (Member # 6801) on 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.

Posted by Tony Bandiera Jr (Member # 2365) on 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...

Posted by Marcel Birgelen (Member # 6801) on 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

Posted by Nguyen Jack (Member # 7530) on 03-04-2019, 04:02 AM:

Thanks for all support,

After update newest software 2.3.1 , i don't see problem.
I still follow it a few days.

Posted by Tony Bandiera Jr (Member # 2365) on 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.

Posted by Marcel Birgelen (Member # 6801) on 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?

Posted by Sam D. Chavez (Member # 1841) on 03-04-2019, 02:45 PM:

Tony, please give it a rest. You are starting to sound like Gulbrandsen on a bad day.

Posted by Jarod Reddig (Member # 6363) on 03-04-2019, 09:02 PM:

Yikes .

Nguyen hopefully the problem stays away now after the update.

Posted by Tony Bandiera Jr (Member # 2365) on 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?

Posted by Gordon McLeod (Member # 33) on 03-09-2019, 03:58 PM:

I was always taught when troubleshooting break the problem in half and you can reduce the number of places to look by then breaking the half the fault was in in half again
outside of the usual is it on and the fuse good [Smile]

Posted by Sam D. Chavez (Member # 1841) on 03-09-2019, 05:28 PM:

quote: Tony Bandiera Jr
I am disappointed that this was all you wished to contribute to this discussion.

If the topic is moving along and I have nothing specific to add, I follow along. There are many fine technicians working with todays projectors so I don't feel I have some sort of edge.

You on the other hand feel a need to draw attention to yourself even when you are in over your head. When you get called on it you respond with belligerence. As I advised, give it a rest.

Posted by Marcel Birgelen (Member # 6801) on 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.