HDMI 2.0 Troubleshooting Guide

General Background
 
This article covers basic troubleshooting guidance for HDMI devices and systems using the SIX-G. This is a practical field service guide and not a lab guide or debugging tool for manufacturers. We use the divide and conquer process of elimination by being able to inject known signals into an HDMI system, and it works quite well in identifying about 99% of issues that are commonly encountered in the field. At this writing (Sept 2015) the industry is in the middle of change - again - 4K UHD is upon us - and we just got done switching everybody to 1080P!

Background Terminology
 
We are going to using some terms I wanted to explain before delving into troubleshooting:

• Sink - A device that receives an HDMI signal - like an HDTV
• Source - A device that sends an HDMI signal - like a set top box or Blu-ray player
• Repeater - A device that both sends AND receives an HDMI signal - like an AVR, Processor or Switch.
  

Common Problems & Solutions
 
No Picture

• Color space mismatch
• HDMI Cable is too long
• Extender problem - CAT 5e too long for spec
• No power on extender
• Display or distribution system (extenders, DA, matrix, switch, AVR, etc.) does not support resolution
• Improper copy guard (HDCP)
• Outdated firmware in TV, AVR or distribution component.
• Clock stretching issue (HDMI early versions don't support)

 
To troubleshoot with the SIX-G inject known high-resolution signal into TV - verify static patterns and motion patterns; if the pattern does not display change to a lower resolution format.
 
Example: 2160P60 4:4:4 or RGB - NO PICTURE, change to: 2160P60 4:2:0 - PICTURE - in this scenario anything going though HDBaseT system should not pass (limited to 10.2 Gbps) - see below:

If directly connected to the display it depends on the display specification. In some cases it could also be port specific  - some ports support the higher resolution signal and some don't - you can test ports directly with the SIX-G.

Can't Pass High Resolution

• Check setting on source if available in the menu - see if a lower resolution will pass video.
• Make sure the SYSTEM is compatible with the resolution you are trying to send.
• Now that we have moved to 4K there are a lot of mixed systems out there - make sure sink, source and repeater are rated for the resolution you are trying to send.
• Make sure HDCP compatibility with all devices.

Troubleshooting with the SIX-G - Inject known resolutions and timings into the suspect system. Lower the resolution until you can get a test pattern to appear. Test sink and repeater separately to determine while component is not passing the higher resolution and replace that component.

Sparkles in Picture

• Set source to a lower resolution
• In a distributed system - same thing - set source to lower resolution.
• This is usually a bad HDMI cable or a poorly terminated CAT cable or inferior CAT cable.
• The higher the bandwidth the signal the more critical cable selection becomes.

 
Troubleshooting with SIX-G - inject lower resolution signal until sparkles go away. In distributed system test all source-sink-repeater test points for defective CAT run or HDMI cable.

Picture but no Sound

• Mismatch between source or repeater and sink for audio CODEC
• Occurs when HDCP handshake not completed
• Try forcing 2 channel audio if possible
• Make sure AVR and Display have latest firmware

Troubleshooting with SIX-G - inject various audio formats until sound returns - this will verify that connectivity is there. Use SIX-G to verify that the EDID in the display has the correct audio format listed. Usually this symptom is caused by outdated firmware - make sure and update all devices.

Matrix Switch in Mixed Signal Environment - Some displays have video, others do no

• By their very nature - without a scaler in line - mixed signal distribution systems will lock on to the lowest common resolution based on EDID. A source device can only output one signal through the HDMI cable at a time. If you force a higher resolution than the display can handle you won't get a picture on capable displays.
• Set all displays to lower resolution is an option.
• With 4K UHD and HDMI 2.0 and HDCP 2.2 must be careful - evaluate all components for compatibility - both resolution & timing plus HDCP compliance.
• Program control system so 4K UHD sources with HDCP 2.2 are only routed to compliant displays.
  

Troubleshooting with the SIX-G - Test all displays for maximum resolution and HDCP compliance.

HDMI Tips for Installers

• Use Active equipment over Passive wherever possible
• Insure all devices are on the most recent firmware
• Insure all devices are on the same AC circuit if possible
• Keep solid HDMI runs under 25ft (use 24AWG) and go to HDBaseT extenders for runs over 25'.
• Use best cabling possible, the higher bandwidth the better.
• CAT5e or better - use shielded (STP) when you are not absolutely sure what is behind the wall.
• Use only solid copper CAT cables - no CCA.
• Don’t over complicate the system with too many devices in series. Too many handshakes cause unexpected and unwanted results.
• Try to buy all the HDMI devices and HDMI cables from one vendor as they have been tested with each other assuring system interoperability.
• Cycle power on all devices in the system - this will cause a hot plug event and will cause the source to read the sink EDID again and possibly return the system to normal operation
• Make sure everything in the system is HDCP 2.2 compliant in a UHD distribution system.
• Clock stretching issues are common in some STB with older HDMI chipsets (although they look new). This will cause a no picture situation. You can use EDID minder to fix this, and some connectivity companies’ even list a fix for clock stretching as a feature in extenders and matrix switches.

When using POE extenders - make sure they are IEEE 802.11af - this ensures that you don't damage downstream or upstream components