Possible handshake issue?

[Snowfire]

Having a bit of a cable issue and wondered if anyone has any ideas of the possible cause.

I am running a 10m fibre optic cable. Cable is Ruipro which after reading reviews on here it should be up to the job with the below:

TV - LG OLED55CX5LB
SKY Q 2TB UHD box
Sonos Arc
HDMI Switch

Now the issue I am having is very odd... If I plug the cable directly into the Sky box I can't get 8 bit or 10 bit to work at all. 1080p etc will work fine no issues. In the other modes I just get a pure black screen no flicking or fuzziness.

If I plug the 10m fibre cable into my HDMI switch, then use the Sky Q cable provided then I can get 8 bit to work, but 10 bit will not work.

If I select 10 bit as above, then the screen will go black, if I press left and select on the controller then it will use 10 bit mode, but the screen stays black. Now oddly, if I unplug the sky cable out of the switch and I plug it back in, the picture will come on and 10 bit will work fine. It will stay working perfectly fine with no drop outs etc, so I believe the cable to be working perfectly okay. Problem is, as soon as I switch the tv off, or the sky box off, then when I turn it back on 10 bit will not work again and the only way to fix is to unplug the Sky cable and plug it back in. Sometimes however doing this audio will not work and obviously this is not a long term fix.

Now I know I can watch uhd in 8 bit for the time being, but would really like to get this sorted before hdr properly goes live for Sky.

For reference Ruipro sent me a new cable as well.

I believe it to be some form of handshake issue but not sure where to tie it down to. The Sky box is the black and silver one which I believe to be a V2.

Do you think it's worth trying a replacement Sky box ?

 

[Otto Pylot]

Try connecting the cable directly to the tv bypassing the switch. If that works as expected then it's probably the switch. Ruipro cables are active, meaning that they need to draw a bit of power from the sink end (the device that the cable is connected to). If the switch is not powered, or not delivering adequate power to the HDMI port, then you're going to have issues.

ARC usually requires the enabling of CEC as well. CEC is very problematic as it is not standardized so implementation of the CEC protocols can be haphazard which can affect ARC.

The most reliable connection for 4k HDR is a single cable, source to sink, with no wall plates, adapters, extenders, etc because 4k HDR can be very finicky with its connections. 10m is not really too long for an active hybrid fiber cable but everyone's equipment is different so you need to take into consideration the HDMI chipsets in the source and sink end because ultimately, it's the chipsets that determine what you can get send and receive, not the cable.

 

[Snowfire]

Hi Otto,

Thank's for the reply.

Maybe I didn't phrase it correctly. If I go straight from the TV into the Sky box then I cannot get UHD in 8 bit or 10 bit to even work. I just get no signal message displayed on the TV.

Through the switch 8 bit works fine, no problems what so ever.

Bit further testing today trying different methods, if I power the sky box on first and leave it for 10 seconds, then switch the TV on, then I can set it to 10 bit. It then works fine as tested HDR content and no drop outs etc. As soon as I switch either the TV off or the Sky Q box (tried both way round), upon turning back on the Sky Q box just resets the resolution back to 1080i and sometimes it will reset it to 1080i with no sound.

 

[Kaledii]

Old thread, but I've had the same issue.
If I connect Sky Q to my Panasonic OLED then I can get up to 4k 8bit, but 10bit is just black. However, if I connect through a Denon or Marantz AVR then all works fine. I don't normally connect directly to the tele, so it doesn't worry me too much, but I got a fright when I couldn't successfully test my newly installed cable!
Has anyone come to a conclusion on this issue?

 

[Snowfire]

Mine turned out to be the Sky box itself. I just logged a fault and they sent engineer out. Told him the box just keeps turning itself off just to make it easier (in case a new one didn't fix 10 bit). He swapped it out and since then it's been fine on 10 bit no issues at all.