Search CE Pro






Print  |  Email  |  Share  |  News  |  Follow on Twitter, Facebook, Google+ or RSS

Test Your HDMI Troubleshooting Knowledge

Isolating the causes of HDMI problems in the field can save time and create satisfied clients. Check out these 8 real-world scenarios.


image
HDMI. Never before have four simple letters caused so much pain for so many custom integrators.

When the technology was introduced back in 2002, it seemed to be the long-awaited one-wire solution to the potential rat’s nest of wiring that always hampered growth of the high-definition signal transmission in residences. And for most consumers with simple setups, HDMI has been a godsend.

But for custom installers who are often asked by clients to “break all the rules” with lengthy wire runs and multiple displays, the one-wire solution became one big headache.

At CEDIA Expo 2011, the HDMI Licensing Group held an all-day symposium to discuss “all things HDMI.” Among the hottest topics were basic and advanced troubleshooting tips, solving real-life situations in some cases. See the highlighted boxes in this article that show eight real scenarios from the AVS Forum website and their likely solutions from integrators. Use it as a fun quiz for your staff.

Also, continue to refer to our resident HDMI guru Jeff Boccaccio, who recently analyzed the inside jacket of HDMI cables.

Basic HDMI Troubleshooting Tips

Avoid the Need to Troubleshoot
Prequalify all the equipment in the home and that you procure in your lab before you start the job.

Consider the Origin of the Problem
Determine if the existing HDMI system has ever worked. If so, what changed? Take careful notes.

Make One Change at a Time
Make only one switch at a time to limit the variables. Again, take careful notes.

Simplify
Configure or “reduce” the system to the simplest configuration that still exhibits the symptom.

Substitution
Substitute suspect devices or components with known-good devices or preferably with test equipment that can emulate sources and sinks with other convenient control functions.

Disable Protocols
Disable CEC and HDCP if possible. Disabling HDCP will immediately tell you if the problem is related to that.

Diagnostic Sequence
Use the diagnostic procedure that provides greatest insight and is easiest to conduct.
image

Problem 1: No Audio


Symptom: A system that consists of a DVR via HDMI to an A/V receiver (AVR) via HDMI to a projector and there is no audio?

Solution: The probable cause is that the AVR is not substituting its audio block into EDID. For the integrator, the short-term resolution is to bypass the AVR; the long-term solution is to replace the AVR.

image

Problem 2: No Picture


Symptom: There is no picture following standby. The client is having a problem with his media server and HDTV. Once the TV goes to standby, the media server and HDTV will not handshake properly and he gets the infamous green screen instead of video. The only solution that works is literally unplugging the HDMI cable from the media server and re-inserting it.

Solution: The probable cause is that the media server not asserting hot plug. Replace the media server or put a “fix it” device between media server and HDTV.

image

Problem 3: Intermittent Flashing


Symptom: Using HDMI for all connections, the setup is a set-top box to a DVR to an AVR to an HDTV, which results in intermittent flashing. However, when the setup is altered to DVD/Blu-ray to AVR to HDTV (all via HDMI), the flashing disappears.

Solution: The probable cause is an HDCP authentication failure. The STB is not processing the A/V receiver’s HDCP repeater bit. The resolution is to swap out STB and DVR.

image

Problem 4: Pixel Errors or "Sparkles"


Symptom: Sparkles occur in the family room display from the STB.

Solution: This is the often the most difficult problem to isolate the cause. A partial list of possible causes includes:
  • Excessive dielectric loss through HDMI cable or HDMI extender or repeater device
  • Excessive skew on the TMDS pairs
  • Poor quality HDTV (poor equalization)
  • Pre-HDMI 1.3 source without pre-emphasis
There is a sequence of tests that need to be conducted to isolate the problem. First, conduct a cable/repeater test with the objective of determining if the HDMI cables to and from the matrix switch and the switch itself are passing good video. If this test passes then the most likely cause is the Extender.
Second, run a test on the Cat extender and then the Cat 5 cable itself by swapping them out. If the tests fail then you should perform individual tests on each cable. If one fails, replace it. If they do not fail, replace the matrix switch.

Third, conduct a cable/repeater test or frame test to determine if the HDMI cables to and from the matrix switch, the switch itself and the extender are passing good video. If you cannot run the cable/repeater test, then run the frame compare test.

Pixel errors or “sparkles” are caused by various things, including:
  • Intra-pair skew - The loss within one of the TMDS pairs. Typically results from differential lengths of the twisted pair
  • Dielectric loss - Distortion or “smear” of the signal due to attenuation of high frequencies
Diagnosing physical layer problems requires very expensive equipment; therefore, diagnosing such problems is by inference. The general symptom of this problem is characterized by sparkles or intermittent snow. The symptoms of some physical layer problems can be similar to HDCP protocol layer problems.





Subscribe to the CE Pro Newsletter

Article Topics

News · Business Resources · Wire and Cable · HDMI · All topics

About the Author

Jason Knott, Editor, CE Pro
Jason has covered low-voltage electronics as an editor since 1990. He joined EH Publishing in 2000, and before that served as publisher and editor of Security Sales, a leading magazine for the security industry. He served as chairman of the Security Industry Association’s Education Committee from 2000-2004 and sat on the board of that association from 1998-2002. He is also a former board member of the Alarm Industry Research and Educational Foundation. He is currently a member of the CEDIA Education Action Team for Electronic Systems Business. Jason graduated from the University of Southern California.

14 Comments (displayed in order by date/time)

Posted by DrFlick  on  04/11  at  09:50 AM

Jason,

I still have the same problem I had with your webcast on this topic when you recommend to “Disable HDCP.”  I think it is very misleading.  Can you provide an example or two of how one would actually do this?

Thanks,

  =D-

Derek R. Flickinger
Interactive Homes, Inc.

Posted by Jonathan  on  04/11  at  10:42 AM

The work around to the offending cable in the above situations, is to replace other items. This does not make sense when you are trying to complete the work and have to stop to convince the client to buy more gear. Even when you prepare the client for problems beforehand, it usually casts doubt on your ability. Clients want to feel confident with their choice of installer from the outset.
In my 25 years of installing, HDMI has been the top cause of the installers nightmare - the intermittent fault.

Jonathan van Staden
Acoustic Interiors

Posted by ghard1  on  04/11  at  11:27 AM

When you recommend “Swap out STB” do you mean with another of the same model or a different model completely?  It is not always possible to swap out to a different model as only one model may be available and most homeowners are not willing to switch providers because their AV guy can’t get the equipment he sold them to work.

Posted by Chad Nelson  on  04/12  at  07:48 AM

Note that the main cause of signal loss through the TMDS channels of an HDMI cable is not dielectric loss - it is skin-effect loss.  Dielectric losses do not exceed skin-effect loss until signal frequencies are much higher.

Chad Nelson
Maxim Integrated Products

Posted by Jason Knott  on  04/12  at  08:33 AM

DrFlick—According to Neal Kendall of Quantum Data, the HDCP can be disabled and enabled using the company’s Quantum Data 780 Test Equipment. However, he says he does know of any way to do that on a DVD player by itself.

Posted by Doc Greene the elder  on  04/12  at  12:44 PM

Once again, proving that Hollywood bites the hand that feeds them. This is the single worst “improvement” ever foisted upon the American consumer. Congress should strike down the analog sunset law. Component video still looks great and allows incredible flexibility.

Posted by Steve  on  04/13  at  08:46 AM

“Isolating the causes of HDMI problems in the field can save time and create satisfied clients.”

The majority of the solutions above involve replacing existing devices, this usually involves additional expense to the client, as well as time to acquire the replacement device.  So, you’re saying that blaming someone else will make the client happy, and are you going to claim someone else wrote the headline?

Posted by jason  on  04/13  at  12:27 PM

Jason, 1 flaw in your logic, Pink tint i’d say is likely a hdmi connection is

given my experiences with various stu’s and stb’s audio analog and 3.5mm-toslink or toslink-toslink is going to be a signal issue from the antenna/satdish connections, id hearing and seeing the same type of static over hdmi, look at your transmission signal first before blaming hdmi..

alot of handshake issues with hdmi can either lead to the hdmi cable or the quality of the actual tv channel signal. i find anything under 65% signal strength is a basic waste time listening or actually watching whether it be local fta dtv or sat paytv.. don’t matter if you use hdmi or you use standard av leads the pits and whistles will still be there regardless..

Posted by Derek R. Flickinger  on  04/14  at  05:00 AM

Thanks Jason.  Spatz (http://www.spatz-tech.com/) is another company that has a similar device.

I guess the real point I was trying to make is that disabling HDCP is not something you “normally” can do.  It you are trying to diagnose a problem using a tool like the one from Quantum Data, then you are beyond the “just swap out all of the pieces” phase and are looking at the actual cause of the failure using a more methodical and technical approach and probably,  This assumes you already have a more thorough understanding of HDMI failures than the approaches presented here.

  =D-

Posted by Eric Pikcilingis  on  04/18  at  08:41 AM

Seriously?

Troubleshooting solutions are
“Swapping out equipment” 7 out of 8 times?

This saves time and creates satisfied clients?  On which planet?

Oh, I get it…...  this was the April 1st issue….

Posted by Tim  on  04/19  at  07:40 AM

I have a Sony KDL-60NX720 LED HDTV. Cable from wall outlet is connected to the set-top cable box. HDMI cable is connected to the tv from the cable box. HDMI cable from the tv goes to the AVR. HDMI cable from my Sony BDP-S580 blu-ray player goes to the AVR. My Yamaha RX-V667 receiver has an audio return channel. The problem I’am having is my tv keeps switching the audio from the tv speakers to my home theater system speakers. How do I get it to stop the audio switching? I want the audio to play through the speakers of my home theater system all the time. Also I’am using 1.4 HDMI cable.

Posted by Doc Greene the elder  on  04/19  at  12:43 PM

@ Tim…. Go Into the Sony and turn off the CEC. Then go into the AVR menu and tell it AVR on the HDMI audio. Unless you are using the TV tuner, turn off the ARC

Posted by Steve  on  04/19  at  12:56 PM

Tim, I’ve heard of similar issues before that were CEC related.  If CEC is engaged in the AVR, try turning it off and see if that fixes it.

Posted by Mike R  on  04/19  at  05:23 PM

Haha! I love CEPro’s new comic section! If it doesn’t work, replace it! Classic!

But for real though. if all integrators would stop trying to use a pair of $80 baluns and just give in and use the higher quality brands, you wouldn’t run into near as many issues. Your clients will not always want to pay for it, but using cheap gear will only cost the integrator more in the long run.

Page 1 of 1 comment pages
Post a comment
Commenting is not available in this weblog entry.

Sponsored Links

  About Us Customer Service Privacy Policy Contact Us Advertise With Us Dealer Services Subscribe Reprints ©2013 CE Pro
  EH Network: Electronic House CE Ideas Store Commercial Integrator ChannelPro ProSoundWeb Church Production Worship Facilities Electronic House Expo Worship Facilities Expo