VI-N tracks not working

[Bryce Warren]

We are having issues with getting our VI-N tracks working, and thought I would see if any of you had some insight!

We have five screens, one of which has 7.1.
HI/VI-N both are working here, and we have the workaround for the CP750 (using digital 2) to get the tracks running at the same time. Captions are working.

The other four screens with 5.1 won't output the VI-N tracks, but HI is working. Captions work just fine as well.

One screen is running a DSS220, the other three are running IMS3000's. All are using CP750s, along with an IRC-28C to transmit to the headsets. Wiring on all of them is identical.

On the 750...
- Channel A is running from the HI OUT
- Channel B is hooked to AUX OUT (8). I did try 7 as well for this.
- Main output config is set to 5.1
- Decode mode is set to discrete


I initially tried adjusting the pots on the 28C, in case the power was just too low, but didn't find any luck there.
Since HI is working on all of them, I tried temp swapping the cables around at the 750 to see if I could get HI to work over channel B, which it did no problem.


With channel A/B both working on the emitter, I am trying to figure out where the issue lies. Have I simply overlooked a setting on the CP750?


Thanks so much for any help!

[Steve Guttag]

I believe you have to "Mute" BSL and BSR on input 1. Before you do that, and without an audience, run content that has HI/VI and put the processor into 7.1 mode using the middle option...see if the BSL/BSR meters bounce. It is possible that pair 4 is not wired to the CP750 (depending on your installation). If you don't get meter bounce, the signals are not getting to the CP750. If they do, then put it back to 5.1 mode and mute the BSL/BSR.

[Bryce Warren]

Thanks, Steve! Will give that a try tomorrow morning at the latest

[Leo Enticknap]

This is what Steve refers to:

CP750_mutebacksurrounds.png

It is possible that pair 4 is not wired to the CP750 (depending on your installation).

That sounds right. If I understand the CP750 correctly, the HI out jack delivers a mixdown of the stage channels, whereas Aux Out 7-8 pass through the HI and VI channels on the DCP. If 7 and 8 are simply not getting as far as the D to A conversion stage, that would explain why the mixdown HI channel is OK, but nothing is coming out of Aux 8. It is therefore important to check that the pins for pair 4 (channels 7 and 8) are actually hooked up on line A of your DB25 to RJ45 adapters on the back of the 750s.

The other thing to check is the channel routing coming out of the IMS3000s (Configuration > Cinema audio > Channel mapping); specifically, that 7 and 8 are the HI and VI outs. The ISDCF template will work for this

IMS3000_audio_config.png

You can't change these settings in the DSS220 - the channel number on the DCP is the AES output channel, period.

[Bryce Warren]

Thanks to you too, Leo! That's the exact box I planned to tick tomorrow, I will confirm that pair 4 is making it to the 750 in the first place, then check the mapping for the IMS as well.


Ill report back with any news!

[Harold Hallikainen]

As I recall, the CP750 manual says the CH8 output is a D/A conversion of AES channel 8. It says nothing about muting main output pins. I SUSPECT the AES3 audio is not getting there (cable issue). Is it possible that this auditorium is wired the same as the 7.1 auditorium with the HI/VI AES3 pair going to digital2, or perhaps nowhere at all? For the 7.1, as I recall, 7/8 is wired to DIGITAL2 and 11/12 goes to the pair 4 (channels 7/8) AES input of the CP750. If the same cable is being used in a 5.1 room, and you play a 5.1 CPL, silence goes to the 7/8 input of the CP750.

So, it seems like a couple choices here:

1. If using the same cable and wiring as the 7.1 room, configure the CP750 to pull CH7/CH8 from digital 2

2. If using a 1:1 cable, DON"T configure the CP750 to pull CH7/CH8 from digital 2 but, instead, from AES pair 4 (channels 7/8).

Good luck!

Harold

[Leo Enticknap]

Good point. We (Moving Image Technologies) supply a DB25 to RJ45 adapter with a breakout cable to BNC coming out of it that carries pair 4 / channels 7 and 8, for precisely this purpose - getting channels 7 and 8 into Digital 2 in a 7.1 configuration. This is what Bryce needs for the 7.1 house. If he is using these (or something similar from another vendor, e.g. Odyssey) in the 5.1 houses, then if the CP750s there are set to 5.1 configuration, channels 7 and 8 will be going into thin air (or more accurately, into the BNC jack for Digital 2, and thence nowhere). For those houses, he would ideally need a straight DB25 to RJ45 adapter, wired for the pre-Tascam Dolby DB25 pinout.

[Bryce Warren]

I think I have mostly found the root of the problem.

All 5 screens are using a straight RJ45-DB25 adapter. I pulled them off this morning to compare the pins, and what do ya know, 3 of the screens are using a different pin out. (attaching images of both, for anyone's future reference)

Theater 1 (with 7.1), does have a box breaking the channels out to run them into digital 2, and HI/VI-N is working in both 5.1/7.1 mode

Theater 2, 4, & 5 - I borrowed the DB25 from T1 to test here, and as soon as I plugged it in, VI-N started working on these screens.

Theater 3 - I completely messed up my details on this one.
It is also a 7.1 theater, but when they installed it (well before my time here), they didn't do the digital 2/pair 4 breakout, so even in 5.1 mode, those channels are vanishing and VI-N is not working in any capacity. The DB25 pins match T1 at least.


I'll be reaching out to our cinema supplier today to get new DB25 adapters ordered, as well as a proper breakout solution for T3.

Thanks again to all of you for the advice!

[Leo Enticknap]

Shamless sales pitch: if your usual supplier can't help, we can: feel free to reach out to sales [at] movingimagetech.com, or call 714 751-7998.

[Bryce Warren]

Thanks Leo!

[Ioannis Syrogiannis]

I can't tell for sure, but it seems like those adapters are those "silver" ones provided by Dolby.
If that is the case, those extra two pins should be still in there, but not pushed through pin 6 (7/8+ Brown) and 19 (7/8- White).
If I were you, Bryce, I would have a look and finish the work myself. At least for 5.1.
If you choose to go that way and all above is correct, you need to twist that pair of cables (Brown and White). Each pair is meant to be twisted, like the ones on Ethernet cables, between the RJ-45 and the DB25. If the rest of the pairs are not, don't try to remove the pins. If you don't have that tool to do it, you will probably damage them (search for crimp pin tool to see what I am talking about).
image.png

[Bryce Warren]

Amazing tip! Yes indeed, both pins are just hanging out inside the connector.

Got them pushed through and working right away in one theater! Now just to do the other two