Sky box > new 65" TV : picture glitches

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matt17

92 posts

Master Geek

#306186 3-Jul-2023 15:45

Hi all

Have had a look around the forum but couldn't see an answer to this issue.

I have an old Sky box that is connected to a Samsung 50" FrameTV via HDMI cable : it works fine. I purchased a Samsung 75" FrameTV that is installed on the other side of the wall from the smaller TV, and I (sometimes) want to watch Sky on the bigger TV. So I routed an HDMI cable through the wall, thinking I'd simply connect the Sky box to the bigger TV using the HDMI cable. Not so simple : the picture glitches (ie appears, disappears for a few seconds, then reappears - then repeats this process over and over...). I figured it was the HDMI cable - so tested all manner of permutations (a different cable, the original cable that drove the 50" TV without an issue, even moved the Sky box into the room with the big TV - although this did involve using a different aerial plug) : still the same issue on the big TV - but the little TV displays without glitching.

The big TV was connected to a Denon amp - but I removed that from the setup too, thinking it could be the issue - but the glitching continued.

Any ideas why this is happening? Is the Sky box struggling to drive the bigger TV?

Matthew

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26 posts

Geek

#3099200 3-Jul-2023 19:34

It could be an HDMI timing / cable issue.

I found this on the Samsung website <https://www.samsung.com/us/support/troubleshooting/TSG01202002/> , especially if the TV concerned is a Samsung. Other makes may have a similar adjustment .

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matt17

92 posts

Master Geek

#3099378 3-Jul-2023 22:05

Hey

Thanks very much for posting - I'll give that a go tomorrow.

Matthew

matt17

92 posts

Master Geek

#3101328 8-Jul-2023 15:23

Well, I tried rprosser's suggestion (creating a small delay within the TV's HDMI settings) however the glitching still continues.

The Sky box is from 2017 (not sure how to tell which version it is) - could it be that it struggles to drive the larger TV? The Sky box has no issue driving a smaller (slightly older) Samsung Frame Tv...

rlevis

331 posts

Ultimate Geek

#3101410 8-Jul-2023 17:24

You may need an HDMI booster.

fe31nz

1085 posts

Uber Geek

#3101586 9-Jul-2023 01:30

matt17:

The Sky box is from 2017 (not sure how to tell which version it is) - could it be that it struggles to drive the larger TV? The Sky box has no issue driving a smaller (slightly older) Samsung Frame Tv...

You are completely misunderstanding how HDMI works if you think the size of the TV matters. HDMI is a digital signal, not a power source. It is not used to power the TV, with the small exception that it should provide a tiny amount of power to the TV's EDID circuits so that they work even when the TV is unplugged from the mains. The TV gets its power from the mains, and uses that power to run its circuits that interpret the incoming HDMI signal and turn it into a picture. Larger TVs generally use more mains power to produce a bigger picture. They do not need a larger HDMI signal, which would actually make the HDMI signal invalid as it has a maximum level in its specification.

The HDMI signal has to reach the TV intact. If it is degraded in the cable on the way to the TV, there can be bad data seen by the TV, causing glitches. The glitches will generally be one of two different sorts, either some corrupt data being displayed, or more usually, there being missing data so the TV has to either display nothing, or guess from the surrounding picture what it might display instead of the missing data. The HDMI specifications say that in order to be called an HDMI cable, the cable must be able to take an input HDMI signal at valid HDMI input specifications and output an HDMI signal at valid HDMI output specifications at the other end. There are a lot of "HDMI" cables around that do not actually meet the HDMI requirements and should not therefore be allowed to call themselves an HDMI cable. I suspect that you have one of these. Some TVs have HDMI inputs that exceed the HDMI input specifications, in that they can take a lower level signal and still read it properly. Your older TV was likely one of these. Your newer TV is likely not, and is therefore not receiving the same HDMI data that the Sky box is sending, unlike your older TV.

So, what HDMI cable are you using? How long is it? Generally, if the cable is longer, the signal at the output will be lower than with a shorter cable. As the length increases, you get to a point where it is not possible to output a valid HDMI signal at other end without using active (powered) circuitry in the cable to regenerate the signal back to valid HDMI levels. So good long HDMI cables do this. They may at the input end boost the signal well above the valid HDMI levels, so that it is within the valid levels when it reaches the output end. Or they may at the output end have a more sensitive HDMI receiver that can validly read a very low level signal, well below the HDMI output specification levels, and regenerate from that a valid HDMI signal to put on the cable output. Or they may do both. But as the cable gets even longer, the signal will need to be regenerated in the middle of the cable as well, and that starts to become prohibitively expensive as you have to send power down the cable to the regeneration circuitry, as well as the data signal. So most of the really long HDMI cables have circuits at the input end that change the signal to an optical format and send it via laser down an optical fibre to circuits at the other end that read the laser signal and convert it back to HDMI format at optimal levels. With the right optical fibre and optical transceivers, it is possible to send a signal like that for many kilometres, but the normal case for HDMI is typically just tens of metres using cheaper optical equipment.

matt17

92 posts

Master Geek

#3101629 9-Jul-2023 11:00

Thanks so much for the very comprehensive explanation - I did have completely the wrong end of the stick with regards how HDMI signals work. It's sounding increasingly like the cable itself is the issue.

I didn't measure the HDMI cable that's running through the wall, although suspect it's around the 4-5m mark. I have another 5m HDMI cable here (brand new - although from Bunnings, so is probably crappy...). The odd things is, when I moved the Sky box right beside the big TV and used the shorter (2m) HDMI cable that operates the smaller TV without a hitch), the big TV still glitches. I even tried a 3rd HDMI cable (another short one) - that too glitched.

I admit I don't know the calibre of any of the HDMI cables that are part of the setup (other than the Bunnings one) - some are thin, some fat, some have fancy looking connectors - maybe I'll just play around with them all until I find one that can operate the big TV without glitching - which will then eliminate the TVs the amp & the Sky box as the sources of the issue.

Matthew

Bung

5444 posts

Uber Geek

Subscriber

#3101632 9-Jul-2023 11:21

Have you tried the bigger TV on any other source like a DVD player? So far the only thing consistent with glitching is the tv.

fe31nz

1085 posts

Uber Geek

#3101780 10-Jul-2023 01:03

Bung: Have you tried the bigger TV on any other source like a DVD player? So far the only thing consistent with glitching is the tv.

Yes, do try that TV with a different source. A lot of laptops will output HDMI also.

fe31nz

1085 posts

Uber Geek

#3101781 10-Jul-2023 01:21

matt17:

I didn't measure the HDMI cable that's running through the wall, although suspect it's around the 4-5m mark. I have another 5m HDMI cable here (brand new - although from Bunnings, so is probably crappy...). The odd things is, when I moved the Sky box right beside the big TV and used the shorter (2m) HDMI cable that operates the smaller TV without a hitch), the big TV still glitches. I even tried a 3rd HDMI cable (another short one) - that too glitched.

I admit I don't know the calibre of any of the HDMI cables that are part of the setup (other than the Bunnings one) - some are thin, some fat, some have fancy looking connectors - maybe I'll just play around with them all until I find one that can operate the big TV without glitching - which will then eliminate the TVs the amp & the Sky box as the sources of the issue.

Matthew

With really short HDMI cables, they should work even if fairly crappy quality. Once you get to 3 metres or more, then you are needing a better cable. At 5 metres, the crappy cables will give trouble. Somewhere between 5 metres and 10 metres you really need an active cable. Above 10 metres, you probably need an active optical cable.

Also you need to consider what HDMI specification is needed. If you are sending a 4K (2160p) signal, you need a higher specification cable. Older cables will be HDMI 1.4, which only does up to 2160p at 30 Hz. You really need 50 and 60 Hz support for 4K/2160p, which requires HDMI 2.0 or above. If your old TV only did 1920p, and the new one does 4k/2160p, then the sources may be negotiating a 2160p connection and the old cables may not do that properly. HDMI 2.1/2.1a is the latest version, but cables with that specification are more expensive.

matt17

92 posts

Master Geek

#3101809 10-Jul-2023 08:58

Thanks heaps for all you advice people! Am away from home for a week - will try upon return, and let you know how I get on.

Matthew

matt17

92 posts

Master Geek

#3115772 14-Aug-2023 16:51

Ok, an update here : bought what appears to be a fancy HDMI cable from JayCar - was about $60 for a 5m cable. It's a Concord WQ7904. It STILL causes the TV to glitch. I have an Apple TV 4K connected to the TV with a different, shorter HDMI cable (looks about 1m, not at all fancy) and that doesn't glitch.

Am wondering what else it could be : the amp?? It's a new Denon AVC-3200X - the TV's 'black box" (it's a Samsung Frame TV, so has one of those 'black boxes' that sits separate from the TV. All the HDMI cables get plugged into that - which is then connected to the amp via an HDMI cable. The 'black box' connects to the TV via Samsung's proprietary cable.

Currently there is an Xbox and the aforementioned AppleTV plugged into the 'black box' - neither of which are glitching.

Tearing my hair out over this!!

Matthew

fe31nz

1085 posts

Uber Geek

#3115911 15-Aug-2023 00:34

Fancy and expensive does not mean it is actually a good cable, I am afraid. There are people who sell cables for thousands of dollars that are no better than the cheap ones. When the advertising starts going on about "oxygen free copper" then you should immediately be suspicious, as that is one of the snake oil phrases used to sell "premium" audio cables. HDMI cables are digital signals, so mentioning things that might vaguely apply to analogue signals is just stupid. Mentioning that the gold plating is "24k" is also a bad sign. The use of gold plating is good - the reason for it is that gold does not oxidise so a layer of oxides can not build up on the connectors and interfere with the connection. 24 carat gold is completely pure gold, and is the gold used for almost all electronic plating work - there is no need to mention the purity in the advertising unless you are trying to actively deceive people that your product is better than others (which will all be using the same gold). Gold is plated on in a thin layer and it being soft and ductile actually helps prevent wear on the connector. I am not sure whether "heavily" plating the connectors is actually a good idea or not - I suspect that they are actually plated to the same standard normally used and works well. But having snake oil advertising does not actually mean a cable is bad either - it is just used to justify a higher price.

The best cables are ones that have been tested and reviewed by someone who actually knows how they work. Failing that, if you can find the product somewhere like Amazon and it has user reviews, that can help weeding out the bad ones. I could not find any tests or reviews of the Concord WQ7904 cable, so I have no idea whether it is actually good or not. For HDMI 2.0, at 5 metres long, it needs to be properly designed.

The problem could be in the amp. Diagnosing things like this is a difficult business, but one of the common ways to do it is to swap things around and see what works and what does not. If the Xbox or Apple TV do 4k 2160p, then try swapping their shorter cables with the new long one and see what happens. If you have a laptop or a PC you can move to the TV that can do 4k 2160p and has an HDMI output, try running them using the various cables to the TV. Then if they work using the cable directly to the TV, try using them as a known good source, but now routed through the Denon amp.

If you know anyone who has a 5 metre HDMI 2.0 cable, see if you can swap cables and see if yours works where theirs does, and vice versus. Also, if they have similar equipment to you but use a shorter cable, see if you can put your 5 metre cable in their system and see if it works properly there.

toejam316

1298 posts

Uber Geek

Trusted

Lifetime subscriber

#3115913 15-Aug-2023 03:28

Also probably pays not to rule out the actual ports on all of the devices in the chain of the issue, too. Swap stuff around and observe where the fault lies based on what has changed and what remains the same. Rule out every element possible until only one remains.

Anything I say is the ramblings of an ill informed, opinionated so-and-so, and not representative of any of my past, present or future employers, and is also probably best disregarded.

matt17

92 posts

Master Geek

#3115924 15-Aug-2023 06:56

Ok, thanks guys. Looks like a round of testing coming up for me!

jay63

65 posts

Master Geek

ID Verified

#3116030 15-Aug-2023 09:47

I had much this same Sky TV issue pop up randomly, earlier this year, after several years of working with a 65” Sony OLED TV via a Yamaha Receiver for surround sound. I thought it was a cable fault but even with high-end cables had no joy - about a 5m length too. After talking with a Sky technician, this appears to be somewhat of a known issue with the Sky Box and possibly a somewhat recent firmware update. I even tried multiple Sky Boxes I ended up hooking the SkyBox directly to its own hdmi port on my TV and passing sound back through the ARC connection for surround sound. It has been working since just an extra cable to the TV now. The root cause issue was somehow the receiver pass through noting no issue with my Apple TV or a Fire TV either with the identical set-up

Hope that helps.

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