Member Avatar for lcw7

Hi all,

Am currently running my systems HDMI output through my lcd tv and it runs fine, however when I switch the input source on the tv to another type (ie Svideo or Scart) and then switch it back to HDMI it will only return with a blue screen saying that there is no signal.

Have been using ATI catalyst control center with desktop area set at 1152*648 (have also tried 1280*720 with a 60hz refresh rate.

Any help would be much appreciated.

System details are

AMD Athlon X2 5200+ Processor (AM2)
AMD 690GM-M2 Motherboard
ATi Radeon X1250 Graphics (SMA)
2048MB DDR2 PC5400 Memory

TV details are

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  • Latest Post Latest Post by dogbreath077

Dani AI

Generated

Brief summary: reported that the HDMI picture disappears after switching the TV to another input and back, leaving a blue “no signal” screen. suggested checking automatic detection; later confirmed that forcing TV detection in Catalyst did not fix the problem.

Likely cause: this is most commonly an HDMI handshake / EDID issue or a driver behavior that disables the digital output when the TV reports it is no longer present. The TV and GPU must re-negotiate parameters when the input is re-selected; if that re-negotiation fails the TV shows “no signal.” It can also be caused by the TV’s input auto-detect, HDMI-CEC/power settings, a flaky cable/port, or a driver bug.

Troubleshooting checklist (ordered roughly by effort):

  • Swap the HDMI cable and try a different HDMI port on the TV. Test with a known-good short cable. Remove any receivers/splitters and connect the PC directly.
  • On the TV, look for input options (labeling the HDMI input as “PC,” disabling “Auto Input” or HDMI-CEC, and turning off any HDMI power-saving features). Menu names vary by brand.
  • In the graphics driver, try both the latest and a known-stable older Catalyst driver. Use the driver’s “Detect displays”/reset options and set the GPU to drive a single display (not extended desktop) while testing.
  • Create a standard TV mode (native resolution / 60 Hz or 50 Hz depending on region) rather than a custom desktop mode, or use a utility to read/save the TV EDID and force it to be presented to the GPU (examples: Monitor Asset Manager / PowerStrip). Keep a way to revert changes (safe mode) in case of black screen.
  • If re-detection still fails, try an EDID emulator or a powered HDMI splitter/emulator that maintains the handshake when the TV input changes.
  • Confirm by testing the PC with another TV/monitor; if the problem follows the PC it’s driver/hardware; if not, it’s the TV.

If none of these steps restores reliable behavior, gather driver version, OS and TV model and escalate to the GPU vendor (AMD/ATI) and the TV maker with the reproduction steps — this combination of symptoms is commonly fixed by a driver update or an EDID-handling change.

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Member Avatar for dogbreath077

I've seen some video cards that will detect the presence of a TV, and enable the appropriate options for the detected configuration. My Nvidia is like that. If I don't have everything connected, it won't give me the option to change any settings. I believe your video card is detecting a disconnected connection and recognizing it as a lack of a TV altogether, thereby shutting off the video stream to that cable. Look in your video card control panel and see if there is a redect sequence, or an autodetect option that can be enabled. In my Nvidia control panel, I have a redetect sequence that I must do everytime I touch a cable or connection device. Good luck, and repost with results.

Member Avatar for lcw7

Thanks for the suggestion, it's much appreciated. I have checked the settings in control center and there is a setting that forces tv detection, I have enabled this but it still wont display once I shift back and forth between sources.

Member Avatar for dogbreath077

If forcing a detection doesn't work, then report it to the video card manufacterer. This may be a bug they need to fix, or possible already have a patch for.

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