HDMI issues

[sherbertdab127]

The venue I am working in over the summer is having an issue - I haven't been able to figure out what the actual issue is and I would love to know.

Basic set up - we have two spots from which a device with a HDMI output (or suitable adapter) can be plugged in. These are on stage and from the projector box - the on stage HDMI is run under the floor and along the wall. Both cables run into a Denon receiver.

An external let has come in and handed me their device with has a mini digital port out, an adapter was found and the set up was tested and functioned fine.

They have since not been able to get any signal through the HDMI to the projector. When nothing is plugged in, the Denon logo is projected. When I plug in the mini dp, the screen goes blank.

In response to this, I tested with a laptop we have backstage and it sends signal perfectly.

My assumption here was that their device was malfunctioning or the mini dp out or adapter was not working.

I switched out the adapter, no change. I have checked the settings, the device is giving no indication another screen is being picked up.

I suggested they see if there is another device they can use. They brought in a laptop, which had the exact same issues, which makes no sense! My logic is, either the HDMI isn't working and no device should be able to broadcast through it - which isn't the issue as the backstage laptop we have has sent signal fine - or their original device has a dodgy port, which isn't the issue as two devices are now not sending signal.

At this point, I gave up on the stage side HDMI (which on reflection, I should have done sooner but I was so sure their initial device was faulty I just hadn't thought it through) and moved up to the projector box HDMI which worked perfectly - with ALL devices! Both of their devices broadcast properly over the HDMI in the projector room.

I've done some research into HDMI leads and different types but from what I can tell, they're all backwards compatible and both of their devices are older than our test laptop. All three devices are running on Windows 10.

Is there something here that I am missing? 

[Andrew C]

You've tried re-booting EVERYTHING?  Then try again starting in a different order.

I've had similar weirdness with our Aten kit.

[timsabre]

How long are the hdmi runs? In my experience anything over 10m becomes a lottery, not all hdmi outputs are created equal and some will go further than others. I would suspect this is what you're seeing here.  You can get various types of extenders but the same variability applies. 

Edited July 12 by timsabre

[Robin D]

We had a similar problem in our village hall connecting devices to the projector 4.5m up in the air. Bought one of these frim CPC and put it in circuit at the device end if we have a problem and it solves it every time. Odd behaviour abound everywhere though. We had two presenters in from the local authority with apparently identical MS Surface Pro's issued by the council, and HDMI adaptors. One worked without the amp the other wouldn't. Swapped the adaptors over but the one device worked and the other didn't. Put the amp in circuit and it was no problem. Not that the device takes phantom power over HDMI so does not need the psu.      

[Stuart91]

It might be an HDCP problem. If a copy-protected source can't see a "compliant" display at the other end of the HDMI line, it simply displays a blank screen. No warning message, so can be hard to detect. 

I'd try running their content on your laptop and see if that works...

[TomHoward]

HDCP can often be 'solved' with a Chinese Aliexpress/Amazon HDMI splitter just after the laptop - using just one output - if you have one to hand

[ferretwrangler]

The fact that the Denon logo disappears suggests that a valid signal is being received, as others propose this is undoubtedly HDCP. Perhaps the Denon unit has an analogue output for audio or video which means it is non-compliant? A non compliant image often appears as dark grey but given its not garbage and the logo disappears it certainly feels like the signal is valid.

The amazon 1>2 HDMI splitter route would seem a very sensible test - they are tremendously cheap and will probably solve the issue.

[ninjadingle]

Given that everything works in the projection booth I'd suggest this isn't HDCP related.

Is the stage side cable an active one? Some devices don't have enough power on the HDMI port to power an active amplifier, so although the Denon unit is seeing a connection on the line the laptop doesn't have enough ooomph to get the signal to it. Yours probably does.