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Problems using HDMI over Cat5 Extender

G

geoffd

Member
I am using an HDMI over Cat5 Extender to get the output from my Hummy (an HDR-FOX T2) in the front room to an LG TV in the back room using under-the-floor Cat5 solid cables and wall sockets. The Cat5 cables are about 12m so well within the 30m limit of Cat5. I had a lot of frustration trying to get the Cat5 Extender to work but I have finally narrowed down the problems to just two.

The first problem is that whenever the Hummy has been powered down, on powering back up the picture on the LG TV in the back room is grey snow with occasional flashes of picture or sound. I have tried every combination of power up sequence but once the Hummy has been powered down then the picture remains broken. The only way I have found to fix the picture is using an old Toshiba TV. I plug an HDMI lead from the extender in the back room into the Tosh (the Tosh needs to be plugged in but doesn't need to be switched on). I then reconnect the extender to the LG TV and it then works perfectly.

I have tried using a different make of Cat5 Extender and a different TV (a Panasonic) and all combinations give a broken picture whenever the Hummy is powered down.

This certainly points to a problem with the Hummy so I have also tried using a different HDMI source, a DVD player (also an LG). With this I always get a perfect picture no matter what I power up or down.

If the Hummy is directly connected to the LG TV there is of course no problem so it is only when connected through the Extender. I understand that the problem is probably related to HDMI handshake so when in a broken state I have tried running a long HDMI cable directly from the Hummy to the LG TV and that works fine but if I then reconnect using the extender (without powering anything on or off) and the picture is still broken. This suggests to me that the HDMI handshake is not just between the devices at the two ends of the link, i.e. the Hummy and the TV, but that the Extender is also involved in the negotiation otherwise why would the picture stay fixed after the Tosh has been connected via the extender but not after it has been fixed by directly connecting the LG TV to the Hummy.

I could live with this problem (provided my old Tosh TV continues to work) as I don't often power off the Hummy except there is then problem number two!

Problem two is that almost every time I switch my garage light on or off, the picture on the LG goes off momentarily. I had thought this might be because it was a fluorescent tube but I tried replacing it with a tungsten light fitting and also tried changing the switch but it was no different. At first I thought it was just the garage light but I have since noticed the problem occasionally when other things switch on or off such as the central heating boiler. Again, I could live with this except that sometimes the picture comes back broken, just like when the Hummy has been powered down, and I have to resort to using the Tosh to fix it. I have tried the other Cat5 extender and that is just the same. I have also tried my other HDMI source, the DVD player, and the picture from that doesn't even blink no matter how much I switch the garage light on or off. I have seen that HDMI over Cat5 (and Cat6) can have interference problems from electrical noise but why is it only with the Hummy?

I would appreciate any explanations or suggestions as I don't know what to try next. Is anyone out there successfully using a Cat5 Extender with a Hummy or experienced similar problems? Any theories as to why the Tosh might fix the picture? Is it the make or because it is an older non-HD TV whereas my others are HD? Why are these problems confined to the Hummy and not the DVD player?
 
There is somebody else on here who uses or has used HDMI over Cat5, but not many.

I can do nothing other than point out the bleedin' obvious: none of this is within specification for an HDMI interface, so is not guaranteed to work at all.
 
I have an HDMI over CAT5e extender between my HDR-Fox T2 units and a 'portable' 21" Samsung TV. It works perfectly.

However, my setup is not as yours.

Firstly I have two HDRs plus a Chromecast, ROKU3 and a Sony BluRay player. The HDMI outputs on each device are connected to an input on an 6X2 HDMI matrix. This matrix has two outputs, one of which goes to my regular TV (Samsung 39" LED) which is directly above the said AV equipment. The other is connected via the HDMI over CAT5 extender to our morning room some 20' away. The HDMI extender transmitter and receiver BALUNs are directly connected with CAT5e cable.

This allows us to watch the output from any of our AV equipment in either room. We can even watch output from a different source on each TV so no family squabbles!

I am not saying this is right for you, but the HDMI matrix works a treat for us. I had a 4X1 matrix to start with but my needs grew over time. I would recommend going for the 6X2 unit off the bat as a much more responsive unit than the 4X1 one ever was.

You might find that adding the active HDMI matrix improves/eliminates the HDMI 'handshake' issue that you think you have. Certainly, I do not have any handshake problems, but then again, I have a different make of TV.

This is the unit I have but looks like it's not available at the moment:

http://www.amazon.co.uk/gp/product/B00HM874WU?psc=1&redirect=true&ref_=oh_aui_detailpage_o05_s00

HTH
 
You state that the cat5 is routed under the floor. Have you checked that it does not pass over or run near power cables. It might explain why switching lights on and off affect things.

EDIT: in fact, I suspect, even turning the humax on could cause a power surge/blip in circuits ...
 
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Wallace said:
You might find that adding the active HDMI matrix improves/eliminates the HDMI 'handshake' issue that you think you have.
Click to expand...

That's a very good thought. I had originally intended using a simple HDMI splitter but the one I bought stopped working after a few weeks (before I got the Cat5 extender) and a second one I bought didn't work at all. Not even with the DVD player so I can't blame the Hummy.
 
HarveyB said:
Have you checked that it does not pass over or run near power cables. It might explain why switching lights on and off affect things.
Click to expand...

It does pass over one power cable but that is unavoidable. However it is only a spur to a 13 amp socket so I could disconnect it as a trial.
 
From what you have told us, I think you need to have your house wiring checked by an electrician.
 
HarveyB said:
Yes! Do you want me or my dad?
Click to expand...
Neither, until you've got a clue. What do you even mean by "power surge" anyway? How can turning on something so small cause a surge or a blip or whatever other meaningless term you care to invent? Really, people bandy these terms about like they know what they are talking about when in actual fact they haven't a clue. So, please free to enlighten us all with your engineering knowledge of such things.
 
Turning it on at the mains switch at the rear could, possibly, generate some interference which could propagate along the mains wiring (conducted emission), but waking it up from standby almost certainly wouldn't. Having achieved conducted emission (despite the measures they would have taken in order to pass the CE EMI requirements), the interference would be no greater (and a lot less) than the interference from other environmental factors.

The reason for not routing telephone cables in parallel with mains conductors over a distance is to avoid 50Hz hum being audible on the line. That ain't going to interfere with an HDMI signal, or be at a voltage level comparable with the signal. The usual problem with HDMI and interference is emission from the HDMI link swamping the UHF TV signal (which is in-band, and at microvolts).

The problem with this extended HDMI set-up is almost certainly going to be the handshaking between the source and the receiver. The Humax HDMI interface shuts down if it cannot get HDCP authentication from the display device, whereas other sources might just downgrade to standard definition. HDMI matrix switches re-authenticate the interface so the source only has to negotiate with the switch and not over the full length of the link to the ultimate destination.
 
Black Hole said:
The problem with this extended HDMI set-up is almost certainly going to be the handshaking between the source and the receiver. The Humax HDMI interface shuts down if it cannot get HDCP authentication from the display device, whereas other sources might just downgrade to standard definition. HDMI matrix switches re-authenticate the interface so the source only has to negotiate with the switch and not over the full length of the link to the ultimate destination.
Click to expand...
Thanks for that. It certainly seems worth trying an HDMI matrix so I have just ordered one. I will report back the results.

sceptic said:
Did you run shielded cable? Its normally recommended for extenders...
Click to expand...

No. None of the specs of extenders I looked at mentioned using shielded cable. It was only when I started investigating the problems that I saw references to shielded cable. Unfortunately, getting the cables under the floor was done before laying a laminate floor in the back room and a new carpet in the front so very difficult to anything about it now.
 
Just to add. My short run of 20' between HDMI transmitter and receiver is made using no-shielded CAT5e cable, if I remember correctly.

Good look with the HDMI matrix. I am really pleased with mine.
 
My HDMI matrix arrived and before testing it with the Cat5 Extender I thought I would just plug in the Humax and my DVD player as input and my Panasonic TV as output. I powered up the matrix then the Humax then the TV. No picture or sound! Tried powering up the DVD player and switched to it and it worked, no problem. I tried powering up in each possible sequence but still nothing.

Seems that although the HDMI on my Humax will work with a straight forward TV connection it doesn't work properly with anything else. If I have got a faulty Humax then it seems a strange kind of fault. Have there been any hardware revisions to the T2? Mine was quite an early one.
 
There has been a couple of revisions AFAIK. But not wishing to rub salt in, my three HDRs are the 'old' type and I don't have any issues with the HDMI matrix or the HDMI CAT5 extender.

I think the later versions have the antenna connections on the rear of the unit mounted vertically.
 
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Just thought I would weigh in here with my experience since I seem to be one of only a few people using these cat5 HDMI extenders with the Humax. My Hummy is located under the stairs next to the consumer unit which is also where the aerial lead comes into the house and is distributed to various rooms. It is connected via a pair of 20m cat5e cables to a TV in the kitchen which carries the HDMI signal one way and IR back the other.

I have found the connection works well at up to 720p but is less reliable at 1080 - not a problem as the TV is not huge and not native 1080 in any case. The connection seems to come and go just fine when the hummy powers down and comes up but it does glitch occasionally with very brief noise on the sound and picture. This seems to be related to noise along power lines (the cat5e cables run in ducting under the kitchen floor but there are power cables all over the place under there as well. I have tried wrapping the exposed cables under the stairs in foil to give some screening from all the power around the consumer unit but this has not helped. I tried a different pair of HDMI extenders but these were far worse glitching in a similar way but much more frequently.

In short I found this setup is acceptable but not perfect but it beats having the hummy in the greasy kitchen environment (our only functioning TV BTW).
 
Andy Hurley said:
but it does glitch occasionally with very brief noise on the sound and picture.
Click to expand...
Maybe this is similar to the problem I am having when the garage light is switched on or off.

As Wallace has three Hummies that all work with a Matrix, I thought I might risk getting another T2 off ebay. I had considered a new HDR-2000 but, although I don't use a great deal of it, I wouldn't like to be without the CF. It should arrive sometime next week so fingers crossed.
 
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