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Troubleshooting HDMI Problems

HDMI problems are where the OSD's (On Screen Displays) and other inputs work, but the HDMI inputs do not.  This can result in no picture, no sound, or both.  Sometimes the source device will display an error message, or the TV will display a "no signal" error message.  I have even seen cases where HDMI problems cause "snow" in the picture and hissing sounds in the audio.  Plus, HDMI Consumer Electronics Control issues can cause any component to act in unpredictable ways

Background:

Before HDMI, there was a perfectly good digital signal interface called DVI.  That system used the exact same signal format used by HDMI. In fact, you can get adapters that will allow HDMI sources to work with DVI displays and vice-versa.  Its downfall was its two shortcomings:

  1. It carried no audio, so separate left and right audio cables had to be run between devices, and
  2. It used no copy protection.

The Hollywood content producers realized that all their customers are crooks who, given the chance, would make thousands of digital copies of their movies and sell them on street corners, in bars, and on blankets at the swap meets.  Something had to be done!  Enter HDMI.

The HDMI standard includes a copy protection scheme called HDCP.  Whenever you turn on an HDMI source device (cable or satellite TV set top box, DVD player, BluRay player, or whatever), it sends data to the receiving device asking "What kind of device are you?"  If it answers "I'm a TV," then the source device says "OK, here's your movie."  If it doesn't answer at all, or if it answers "I'm a Digital Video Recorder," the source device tells it to go jump in a lake, which is bad for electronics.  When you send your HDMI signals through a surround-sound receiver, the source device has to ask the receiver what it is, the receiver has to ask the TV to identify itself, and the response has to be passed back up the line to the source.  This whole process is called "handshaking."  What could go wrong?  Well,

  • The receiving device (TV) could be turned off or unplugged when you turn on the source device, so it can't answer the source's question.  By the time you turn on the TV, the requisite handshaking is all over, and the source device refuses to play nice.
  • The source device "forgets" that handshaking has taken place and refuses to output the HDMI signal.
  • The HDCP data stored in the receiving device have been corrupted.  Unfortunately, this cannot be corrected by a simple firmware update, 'cause these data are jealously guarded by the content providers and the TV manufacturers.  Instead, parts will need to be replaced.
  • The TV could be a new type, developed after the source device was produced.  In this case the source device will not understand your TV's response and will refuse to send it any signal.  A firmware update to the source device is needed.  Cable and satellite boxes do this continuously over their networks, so you rarely know it's taking place.  DVD and BluRay players may also need firmware updates, which is why all the newer ones want you to connect them to the internet.  If not, an update must be done via a USB port, with a specially-recorded disc, or by actually replacing a part in the player.  Believe it or not, Pioneer is still paying service centers to update some of their older models by replacing an EEPROM IC containing updated firmware.
  • The surround-sound receiver may fail to interact properly with the source device or the TV.  Again, firmware update(s) of the receiver can be done through the internet, a USB port, playing a disc, an RS232-C connection to a computer, or a special computer interface jig. Older models required this to be done by as many as 4 different methods on the same receiver!  Newer ones use a single update file transferred via a USB key or over the internet.
    So what can you do to fix it?
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    Troubleshooting HDMI Problems:

    The first, and easiest, thing to try is to let the units reset and try handshaking again by turning them off, unplugging them from the power, and powering them up again in order.  Leave all the HDMI cables connected during this process. 

    1. Plug the TV back into the power and turn it on.  It may turn itself off while you're doing the following steps.  No problem; just turn it back on.
    2. Plug the surround-sound receiver (if any) back into the power and turn it on.
    3. Plug the source device back into the power and let it go through its startup routine.

    Hopefully, this solved the problem.  If not:

    1. Disconnect any components in the HDMI signal path and connect the HDMI source device directly to the TV input.  If the TV then works, you will know that one of the disconnected components or HDMI cables must be at fault.  You can start reconnecting cables and components one at a time.  When the TV quits working, you will know that the last thing you added was the problem.
    2. Repeat step 4, above, using a different cable.
    3. Move the HDMI cable to another HDMI input on the TV.  Use the TV remote to select the new input.  If the TV now works, this proves the original HDMI input was bad.  Leave it this way and enjoy your TV.

    If none of this helps,

    1. You can try running component video cables from the source device to the TV.  If it now works, you may want to use the component connection instead of the HDMI cable.

    Otherwise, you'll need to have the TV repaired.

     

    HDMI Consumer Electronics Control (CEC) Problems:

    CEC is a system that allows devices interconnected by HDMI cables to control each other.  For example, pressing the POWER button on a DVD player sends data to your TV to turn on and switch to the DVD input, ready to watch your movie.  Likewise, switching your TV to the CABLE input tells the DVD player to stop playing and power down, 'cause you're apparently done with it.  This sounds like a pretty convenient feature, but things can still go wrong.  If the various devices don't understand each other, your TV might mysteriously shut off while the DVD is playing, or a miscommunication will cause the TV or one of the components to "lockup" and refuse to respond to the remote control or front panel buttons. 

    Any time some of the components in your system start to act CRAZY, my recommendation is to go into the menus of all the connected devices and turn off the CEC feature.  Of course, doing so is only complicated by the profusion of tradenames for this feature, like:

    Just find anything in the menus called "control," "link," or "sync" and turn it off.  If that fixes the problem, leave the feature turned off.