Projector connection randomly losing signal during lessons.

[jonnykewell1]

Good morning all,

 

I'm looking for some help/suggestions with regards to an issue we are having with the secondary output to the projector, which suddenly loses signal at random times during Lessons. We've recently had our AV breakouts and wiring updated to HDMI by an AV company and the output drops when using HDMI-HDMI connections and HDMI-DisplayPort via a display port adapter. When switching back to VGA and an audio cable everything starts to work again.

 

So far the team onsite has done the following troubleshooting steps but it still randomly stops working.

 

-Teacher computers are HP Pro One 440 G4 23.8-in AiO. BIOS to latest version, some machines work on HDMI-HDMI some don't

-Tested with different HDMI cables both at the machine side and with the one through the ceiling which is 10m

-Only seems just to work perfectly with VGA + audio cable

-Updated video card drivers with latest version

-A laptop works via HDMI but still intermittent

-Project Epson EB-X39 (currently awaiting the onsite team to update firmware on the unit)

 

Any other suggestion on things to try would be welcomed or experiences of something similiar as it's really starting to cause headaches.

 

Thanks,

 

Jonny

[Chaniel]

How random are we talking? Does it cut out mid-lesson when actively using the computer? Is it after freezing and unfreezing? After a period of not being used (e.g. powerpoint left displayed, but not frozen)?

 

How long are the HDMI cable runs?

 

Are the projectors running in any sort of eco mode?

 

Have you tried any sort of HDMI signal amplifier?

[jonnykewell1]

Hi @Chaniel,

 

I've gone back to the onsite team to ask them your first question with regards to just how random it is.

 

I believe that the cable run is about 10 meters from projector to wall socket and then a 1m cable from the wall directly into the PC.

 

That's a good shout with regards to eco mode, I suggested a firmware update but didn't consider some eco-mode settings, I'll pass that on.

 

I don't believe we have any sort of HDMI signal amplifier to be able to test currently but it might be worth investing in one just to see if it makes a difference.

 

I'm certainly leaning towards a signal issue with this one.

[Chris_Cook]

Do you know what sort of hdmi cable was installed? Was it active or fibre, or just a plain cable? 10m is the limit on hdmi if I remember right, unless you use an active cable of some sort.

 

Its possible some devices don't output as high a signal level as others. We used to get this with some of our really long vga installs.

 

CPC do some fibre hdmi cables at reasonable prices. I was surprised at how easily they went in. This is the 10m, they go up to 50m

https://cpc.farnell.com/pro-signal/psg3328-hdmi-10m/hdmi-active-fibre-optical-lead/dp/AV28912

[bknaggs]

We've had lots of issues with Powerpoint disabling digital secondary displays if a ppt is made full screen before the screen is switched on. When the slide show is exited it kills the output to the screen. It doesn't happen over a VGA connection and it doesn't happen if the screen is switched on before the ppt is made full screen.

 

Something to check perhaps before you start buying/changing bits of kit.

[thebatman]

Do you know what sort of hdmi cable was installed? Was it active or fibre, or just a plain cable? 10m is the limit on hdmi if I remember right, unless you use an active cable of some sort.

 

Its possible some devices don't output as high a signal level as others. We used to get this with some of our really long vga installs.

 

CPC do some fibre hdmi cables at reasonable prices. I was surprised at how easily they went in. This is the 10m, they go up to 50m

https://cpc.farnell.com/pro-signal/psg3328-hdmi-10m/hdmi-active-fibre-optical-lead/dp/AV28912

 

We have had issues if the cables are too long ( >5m ) and the data rate is too high (4k HD) where if they tryed to show videos in HD it would cut out. We have now started to replace the cables with fibre HDMI, yes they cost a more, but they are stable.

[Jaan]

Could simply be the heat with this weather!

 

just came down from the ceiling after messing with a projector....... no way it's within the thermal operating window up there!

Edited July 21, 2021 by Jaan

[psydii]

We've been having similar problems all year. For us it was mostly the use of USB-C in the mix. However in some cases it wasn't, and firmware / driver updates did improve reliability. The most reliable connections have been hdmi->vga +audio adapters (with USB power) over the legacy cabling.

 

It has been noted by one install team that metal connection plates are only about 90% reliable when HDMI/DisplayPort is in use.

 

A chat with VESA a couple of years ago lead me to the conclusion that DP-DP using RBR rated cable would provide the most consistent experience. i.e. generally 1080p as it's support for 4k is quite limited, so it wont try negotiating something fancy at marginal cable lengths.

 

To quote: "Limitations for DP? That is a broad question. If you are referring to cable length, optical solutions are available up to 100 meters. If bandwidth, many USB-C docks operate in a "2+2" configuration, where 2 of the high-speed lanes in the interface are used for DisplayPort and 2 are used for superspeed USB. In this config, if your source supports DP High Bit Rate 2, you can expect up to 4k @ 30Hz. But if using a 15m passive cable, the DisplayPort link will likely train to High Bit Rate and resulting resolution will be 1080p. The DisplayPort link will train to whatever condition works regardless the max supported data rate, often (incorrectly) referred to as DP 1.4, 1.2... DP is controlled by the graphics driver and results may vary with Intel, AMD, Nivida

(my emphasis)

[jonnykewell1]

Do you know what sort of hdmi cable was installed? Was it active or fibre, or just a plain cable? 10m is the limit on hdmi if I remember right, unless you use an active cable of some sort.

 

Its possible some devices don't output as high a signal level as others. We used to get this with some of our really long vga installs.

 

CPC do some fibre hdmi cables at reasonable prices. I was surprised at how easily they went in. This is the 10m, they go up to 50m

https://cpc.farnell.com/pro-signal/psg3328-hdmi-10m/hdmi-active-fibre-optical-lead/dp/AV28912

 

Thanks for this Chris, i'm not entirely sure on the type of cable but i'll certainly try and find out. The thing that's worrying me is that this is a gradual install across the whole site so is only going to become a bigger problem. The cost for replacing so many cables is going to be a fortune and I can't see the AV company coughing it up.

[jonnykewell1]

Could simply be the heat with this weather!

 

just came down from the ceiling after messing with a projector....... no way it's within the thermal operating window up there!

 

Thanks Jaan, sadly I don't think it's a heat issue. It's been happening for a few weeks now, even when we had the colder weather.

[jonnykewell1]

We have had issues if the cables are too long ( >5m ) and the data rate is too high (4k HD) where if they tryed to show videos in HD it would cut out. We have now started to replace the cables with fibre HDMI, yes they cost a more, but they are stable.

 

I must say I am leaning towards this being the problem.

[SamanthaD]

I would go as far to say any HDMI run to a projector should not be done on standard copper. Amplified copper cables are ok (we use the Van Damme 10 and 15m versions with no issues) but anything over that should either be fibre or twisted pair.

 

Also remember each break in the chain effectively adds a meter to your overall length. So you suggest the main cable may be 10m, with a wall socket to a 1m flylead. Most HDMI wallplates are actually very short F-F cables behind the plate, so add an extra 2m for the 2 connections, plus a bit extra for the cabling, and you're fast approaching 15m overall length on standard copper.

 

Yes it's expensive going to HDMI. Consider alternatives though - would SDI work better for you, or twisted pair? (Some projectors can accept HDBaseT straight in, and I've found the Sy range of transmitters aren't that bad). Perhaps worth halting work until you've revisited the proposed solution!

[Alis_Klar]

Why are most installers just ignoring the HDMI specs and putting in 15M copper non-active cable?!?!?!?

 

We have had so many intermittent issues with our HDMI cable runs. We can switch back to VGA but the quality really plummets and is very noticeable plus most new Touch screens have separate USB inputs for each video input so swapping between HDMI and VGA is a pain.

 

I always insist on twisted pair adapters now.

[jmak]

Any recommendations for cheap HDMI over twisted pair adaptors or do I need to spend a bit of money to get something that works properly? It's for home use and I have a 12m HDMI cable from the projector to a 4 way HDMI switch with a coax digital audio splitter. Even though it's within length limits, I think cable length might be the reason I'm getting intermittent signal loss.

 

Edit: changed HDMI over Ethernet to HDMI over twisted pair. Have didn't five minutes reading and now understand they're different things [emoji3]. I don't need it to run across my network and can easily run a separate cable.

Edited November 23, 2021 by jmak