quote: Fernando Caldeira

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Only the center channel goes, and it is inactive on main display. All the other channels keep working normaly on the display.

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So, the little bar graph of the Center channel drops to zero bars and stays there? Any other messages on the display?

I'm just wondering here... what would be the expected behavior if the connection between the analog out of the CP650 and the amplifier behind it on the Center channel would be shorted?
 

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Posted by Fernando Caldeira (Member # 5680) on 02-15-2015, 06:03 PM:
 
Marcel so you´r saying switch the amps, say L with C, and see if L goes?
 

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Posted by Marcel Birgelen (Member # 6801) on 02-16-2015, 01:03 AM:
 
I guess switching the Center amp with e.g. the Left amp wouldn't be a bad idea. Because by process of elimination you can at least get a problem in your B-chain off your list if the problem remains the same.
 

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Posted by Fernando Caldeira (Member # 5680) on 02-16-2015, 05:11 AM:
 
Brad,

here are the pictures.

It´s a bit of a mess a I know but...




 

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Posted by Carsten Kurz (Member # 5396) on 02-16-2015, 06:07 AM:
 
This main audio out Y-Cable/adaptor looks a bit suspicious to me. However, if the signal goes away on the CP650 display already...

- Carsten
 

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Posted by Brad Miller (Member # 2) on 02-16-2015, 12:26 PM:
 
I think you are actually losing subwoofer too and you just don't realize it. In looking at that pic the DB25 used in the option input is the same type that has given me issues in the past. Once I replaced them, the problem went away forever. That's why I wanted to see it.
 

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Posted by Carsten Kurz (Member # 5396) on 02-16-2015, 02:35 PM:
 
It's probably easy to overhear a missing LFE, but if the center signal disappears from the display signal indicator while the LFE signals stays visible there...? It's hard to imagine what goes on there. The 790 has such a pile of issues, but losing a single channel from an AES/SP-DIF pair...

In theory one could assume a very weird channel mapping on the IMB, but who would do that ?

There have been some reports of lost channels or swapped channels in certain Doremi firmware versions.

- Carsten
 

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Posted by Marco Giustini (Member # 4544) on 02-16-2015, 05:22 PM:
 
if you are 100% positive the LFE is there, I'd think of a CP650 issue or a Media Block issue.

As it has been said, make sure you are on the latest version on your IMB.

Make sure your ethernet cables from the Doremi IMB is as short as possible, that IMB does not like them - among many other things.

Make sure your CP650 is running the latest sw - you may want to ask Dolby for the latest beta version (it won't be further developed) which drastically improves the 790 reliability.

Finally, does the sound come back if you reboot the 650? I know it takes ages and you have patrons in the auditorium.

I am not sure a bad connector could cause the issue you noted, if Brad is right and you are also losing the LFE, by all means your problem is likely to be the connector or a cold joint in it or the IMB adaptor.
 

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Posted by Fernando Caldeira (Member # 5680) on 02-18-2015, 05:26 AM:
 
Brad,

I´ll try to have the instaler change de DB25.

Marco,

I´m 99% shure. Has It happened during a show and the stress lvls were high but I had that question on the back of my mind so i was paying atention to that detail.

I will check the Ethernet cables and probably make new ones.

As for the softwere I´ll have de instaler do it.

A cold joint is like a bad welding?

Thanks for all the help.
I´ll keep you guys posted.

Cheers
Fernando
 

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Posted by Marco Giustini (Member # 4544) on 02-18-2015, 03:40 PM:
 
a cold joint is a a solder joint which is giving intermittent contact.
 

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Posted by Fernando Caldeira (Member # 5680) on 02-19-2015, 04:53 AM:
 
Thanks Marco thats what I thought.

Yesterday we changed the DB25 conector and all 4 ohm converters.

We will be spending the next 2 weeks trying to force the problem, testing all movies for the upcoming festivals.

Lets see what happens

Cheers
Fernando
 

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Posted by Fernando Caldeira (Member # 5680) on 03-03-2015, 02:27 PM:
 
I think we finaly got it. Marco was right. The ethernet cable that conects the server to the IMB had the plug loose so it was going in and out just enough to loose the C channel. Made it happen a couple of times to make shure that was the problem and replaced the cable.

Thanks for all the help.

Cheers
Fernando
 

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Posted by Carsten Kurz (Member # 5396) on 03-03-2015, 02:38 PM:
 
That cable uses 4 AES pairs, each one carrying TWO channels at the same time. You can not lose ONLY the center channel (except if you are using a very weird server side channel mapping). So, it is impossible to lose the Center channel without losing the Subwoofer/LFE at the same time. If you say the center channel goes away on the Display, but not the LFE, there must be something wrong with your diagnosis.

As I wrote earlier, it is easy not to notice a missing LFE by ear, but not on a signal
display.

Edit: You don't really mean the cable from the Server to the IMB? That is a PCIe connection, i'd say it is impossible to lose just a center channel on that one.
You sure mean the audio CAT5 cable from the IMB to Dolby processor/Neutrik impedance converter?

- Carsten
 

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Posted by Sam D. Chavez (Member # 1841) on 03-03-2015, 02:55 PM:
 
Some 650's display phantom noise on the sub channel display so this might explain both your points.
 

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Posted by Fernando Caldeira (Member # 5680) on 03-04-2015, 05:54 AM:
 
Carsten, my mistake, you are absolutely right.

I have a video I did on my phone of the problem has it happened. Is the a way to post it here?

I´ll get some pictures up of the cable that was giving me the problems. Perhaps that will answer some of the doubts.

I don´t want to be misleading anyone.


 

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Posted by Carsten Kurz (Member # 5396) on 03-04-2015, 08:21 AM:
 
Oops, all in all, a lot of adaptors used on that installation. You really have to keep an eye on them. And most installers seem to buy only the cheapest CAT5 cables around...

- Carsten
 

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