Display Intermittently 'Blacks Out' - AVS Forum
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post #1 of 17 Old 04-03-2011, 09:46 PM - Thread Starter
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Hi -

I was wondering if anyone out there has run into this problem: The display intermittently 'backs out'. Happens on all connected HDMI sources (BD DVD, HD Cable, Apple TV, etc ...).

More prevalent in evening. Black out is only momentary. Picture comes back quickly. When this condition occurs, it could happen between 4 times in a minute and a couple times in an hour or so.

Here's my set-up.

HDMI Sources --> Denon AVR-891 A/V Receiver --> Siig HDMI Extender TX --> Cat 5e (<50 feet) --> Siig HDMI Extender RX --> Sony KDL55NX810 55" Bravia 3D LED

All HDMI cables are supposedly 'High Speed' - HDMI/Ethernet. All HDMI cables are short 1M or less.

Any help would be greatly appreciated.
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post #2 of 17 Old 04-03-2011, 10:25 PM
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In all likelihood, your problem lies in the HDMI extender and/or Cat 5e cable. The fix would be to replace them with something that works. Which one are you using?
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post #3 of 17 Old 04-04-2011, 07:41 AM - Thread Starter
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That was my thought as well. However, I don't want to jump to conclusions.

For example, when I first set the system up I was having display connectivity issues. Video would appear for 10-15 seconds and then the screen would go back forever. I thought for sure it had something to do with the HDMI extender. After exhaustive troubleshooting, it turned out to be a bad HDMI cable.

The HDMI extender is made by Siig. It uses only one Cat5E cable, and is powered at both ends.

The problem seems to be more prevalent in the evening. Perhaps there is an AC load that is causing interference (e.g. lighting, subwoofer turning on/off due to low volumes).

Today I am going to try the following:
  1. Re-setup the HDMI extender: Relearn the EDIC code into the tranmitter, adust receiver sensitivity level
  2. Put ferrite cores at both ends of the Cat5E cable
  3. Take the subwoofer out of 'Auto' mode and either leave on all the time or off all the time

If that doesn't help, I will try isolating the components. First I will connect the most frequently watched device to the HDMI extender Transmitter (effectively bypassing the A/V receiver).

I will updated the post with my findings.
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post #4 of 17 Old 04-04-2011, 12:03 PM
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Quote:
Originally Posted by TK_Acacia View Post

Perhaps there is an AC load that is causing interference...

That is a possibility. HDMI extenders that use Cat 5e are more susceptible than HDMI cables.
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Put ferrite cores at both ends of the Cat5E cable

May make things worse. They degrade the signal.
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post #5 of 17 Old 04-04-2011, 09:22 PM - Thread Starter
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First thing I did was try to reproduce the problem. I turned everything on and waited for the black out condition to occur. Of course it did not happen for me.

So I went ahead with my plan, not actually witnessing the problem first hand however.

First, I unplugged the subwoofer from the back of the power conditioner and plugged it directly into the wall. My thinking was that in the evening, with the audio levels low, the subwoofer might be switching on and off causing AC spikes that could disturb the video signal. HDMI extender transmitter and receiver (Siig) are both locally powered. The transmitter was plugged into the same power conditioner as the subwoofer.

Second, I moved the HDMI extender transmitter unit from behind the A/V receiver one shelf up to behind the BD player and cable box. I think this is a better place for it, from both a temperature perspective as well as an electrical interference perspective. Where it was before behind the A/V receiver was in very close proximity to high-current speaker cables that could have induced noise.

Next, I installed ferrite cores on each end of the category 5E cable that connect the HDMI extender transmitter and receiver units. The ferrite cores *should* further mitigate any high frequency noise that may be induced on the cable.

Finally, I adjusted the HDMI extender receiver level to the highest sensitivity – ‘7’. It was set to ‘4’. What is interesting is that by playing around with this adjustment, I was able to somewhat recreate the problem. In other words, when it was set to ‘0’, the picture was always black. As I increased it to ‘1‘ and ‘2’, the picture would come back but then ‘black out’ like described. At ‘3’ it would *occasionally’ black out. At ‘4’, where it was at originally, and above, I could not get it to black out. So I left it at the highest level, ‘7’.

I waited for a while for the problem to happen and it never did. Of course the real test will be when the customer tests it in the evening

Fingers crossed.
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post #6 of 17 Old 04-05-2011, 12:55 PM
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Quote: Put ferrite cores at both ends of the Cat5E cable
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Originally Posted by Colm View Post

May make things worse. They degrade the signal.

Why do you say that? Ferrite cores suppress common-mode signals on the cable. They have no significant effect on the differential-mode HDMI signals.

Carl
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post #7 of 17 Old 04-05-2011, 05:26 PM
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I used to think that, too, until I read a research paper on the subject. I posted a link to it in another thread. The eye diagram tightened up. I think at least part of the problem is that even if the signals on the differential pair start out perfectly in sync, they tend to move apart from each other because of differences in cable geometry. Differential mode transmission is a powerful way to reduce the impact of noise on a signal, but it isn't perfect, if for no other reason than the cable connecting the transmitter and receiver is not perfect. For that matter, the transmitter and receiver aren't perfect, either. You can only expect so much from them.
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post #8 of 17 Old 04-06-2011, 02:40 PM - Thread Starter
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The changes I made the other day (recap: removing subwoofer from same power conditioner as HDMI extender transmitter, moving HDMI transmitter away from A/V receiver, ferrite cores on both ends of cat5E, changing the level setting on the HDMI extender receiver from '4' to '7') seemed to improve things markedly, with the most significant change probably being changing the signal level.

However, the problem still exists, just much less frequent. Now, the problem is most prevalent on Apple TV watching NetFlix. But it still happens on other sources (cable) as well.

My current thinking is that '7' is too high. I went back today and set it to '6'. We'll see how that works.

There's a possibility that the HDMI extender could be defective. Swapping it out with another one is also a possibility. But I doubt it.

I could also try slowing down the HDMI from 1080P/60 to either 1080i or 720P. I'm not sure that the Denon AVR 891 will allow me to set that rate. Also, not a first choice from a 'getting the highest level of performance out of a TV capable of 1080P'.
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post #9 of 17 Old 04-06-2011, 03:16 PM
 
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Quote:
Originally Posted by TK_Acacia View Post

...

I could also try slowing down the HDMI from 1080P/60 to either 1080i or 720P. I'm not sure that the Denon AVR 891 will allow me to set that rate. Also, not a first choice from a 'getting the highest level of performance out of a TV capable of 1080P'.

If you are going to change the resolution, probably the best way is to set the AVR-891 to native and then change resolution at the source. I'm not sure I'd want the receiver scaling (except maybe 'up' when necessary) rather than the source.
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post #10 of 17 Old 04-07-2011, 05:51 AM - Thread Starter
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Unfortunately, there is nothing higher than seven (range of HDMI extender receiver signal level is 0..7).

My next theory is that maybe the length of Cat5E is too short.

Extenders are designed to extend the distance between the source equipment and display (sink equipment) beyond the maximum specified distance of an HDMI cable. I am not using the extender for its intended purpose. Rather, I am using it in place of an HDMI cable because when the house was under construction HDMI was unheard of and we ran display connectivity cables consisting of 5x75-ohm RGBHV cable, a RG6QS cable, and a Cat5E cable (intended for IR control). When the customer wanted to refresh his A/V equipment, it made sense to reuse the Cat5E cable for HDMI connectivity rather than opening up the walls and running an HDMI cable. I'm starting to think that this was a mistake.

Anyway, back to my theory. The most noticeable difference seems to be the setting of the rotary switch on the HDMI extender receiver unit labeled 'signal level'. It turns out after talking with some technical folks that it is really not a signal level per se, but rather an equalization setting to compensate for different length cables.

From my previous posts, '0' didn't work at all and '1' through '3' exhibited frequent flickering. When it was set to '4' (where is was originally) it was less frequent and more intermittent. '7' seemed to be the best. '6' was worse than '7' but better than '4'.

Today, I am going to try inserting 50-feet or so of Cat5E to increase the overall length of the cable. Before I add this, I will measure the length of the installed cable using a TDR, and measure the length after. I will probably start out at '7' and see how that works.

Other ideas I have yet to try:
  1. order another HDMI extender (same model) in case I happen to have a defective one.
  2. run an external Cat5E/Cat6 to see if there is a problem with the installed cable
  3. run an external HDMI cable to eliminate the possibility of anything else causing the problem and reevaluate whether using HDMI extenders for this application is viable

By the way, it turns out that this particular HDMI extender product shows up under several manufacturers. The one I have is a Siig. I've seen it also offered by Aurora Multimedia, and Tripp-Lite.

I'll keep you posted.
TK
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post #11 of 17 Old 04-07-2011, 10:31 AM
 
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Quote:
Originally Posted by TK_Acacia View Post

...

By the way, it turns out that this particular HDMI extender product shows up under several manufacturers. The one I have is a Siig. I've seen it also offered by Aurora Multimedia, and Tripp-Lite.

I'll keep you posted.
TK

What this means is that like many products it is likely manufactured by someone different than the company's name on the box. SIIG sells a lot of these type items (I have a SATA controller card from SIIG that I could also find sold by other companies). The only time it becomes a problem is when trying get help about the product since all they've done is rebadge the equipment.

Please continue the updates - I'm curious to see how you resolve this.
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post #12 of 17 Old 04-12-2011, 08:26 PM - Thread Starter
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So the results with the longer cable are in. The long and the short of is that it made no difference.

First, using a TDR, I measured the length of the Cat5E in the wall - 12.5m. Then I used the TDR to measure the cable I fabricated - 14.5m. Combined the two cables using a Cat5E coupler - combined length = 28m.

Basically, everything seemed to scale in the direction of longer cable length with respect to the receiver level setting. '4' seemed to provide the best performance.

Basically, everything worked fine for a while. Then in the evening, the blacking out started occurring again.

I had the customer just use the 14.5m external Cat5E between the transmitter and receiver. Problem still occurred.

Conclusions:
1) Effect of adding cable made no difference on problem
2) There is probably nothing wrong with cable in wall
3) Not sure if the problem is even related to HDMI extenders - is there something wrong with TV, A/V Receiver, interoperability?
4) Is the HDMI extender defective?

I stopped by this evening to replace the HDMI extender components (transmitter and receiver). Used the same power supplies - hopefully that was not a mistake.

If problem still occurs, trying a 10m HDMI cable to eliminate HDMI extenders altogether and rule out bad TV or A/V receiver.

This is getting very frustrating.
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post #13 of 17 Old 04-19-2011, 07:33 PM
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Quote:
Originally Posted by TK_Acacia View Post

So the results with the longer cable are in. The long and the short of is that it made no difference.

First, using a TDR, I measured the length of the Cat5E in the wall - 12.5m. Then I used the TDR to measure the cable I fabricated - 14.5m. Combined the two cables using a Cat5E coupler - combined length = 28m.

Basically, everything seemed to scale in the direction of longer cable length with respect to the receiver level setting. '4' seemed to provide the best performance.

Basically, everything worked fine for a while. Then in the evening, the blacking out started occurring again.

I had the customer just use the 14.5m external Cat5E between the transmitter and receiver. Problem still occurred.

Conclusions:
1) Effect of adding cable made no difference on problem
2) There is probably nothing wrong with cable in wall
3) Not sure if the problem is even related to HDMI extenders - is there something wrong with TV, A/V Receiver, interoperability?
4) Is the HDMI extender defective?

I stopped by this evening to replace the HDMI extender components (transmitter and receiver). Used the same power supplies - hopefully that was not a mistake.

If problem still occurs, trying a 10m HDMI cable to eliminate HDMI extenders altogether and rule out bad TV or A/V receiver.

This is getting very frustrating.

You may want to consider some of the lower priced fiber solutions in the future. It will eliminate any ground issues as well as nearly all of the variable you're facing with CAT5/6.
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post #14 of 17 Old 01-03-2014, 02:25 PM
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How was this issue resolved? I have the same problem and the cable company has been out three times trying to solve the problem by replacing cable boxes.

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post #15 of 17 Old 01-03-2014, 03:27 PM
 
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What type of extender are you using?
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post #16 of 17 Old 01-04-2014, 07:46 AM
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I don't have an extender. Have used for several months/years without using one. Do I need one now?

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post #17 of 17 Old 01-04-2014, 03:02 PM
 
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No but you said you had the same problem which involved an extender. Why not start a new thread and explain your problem and system completely?
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