Need HDMI Black OR Blank Screen Generator

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rfrazier

Well-known member
Sep 30, 2020
482
138
Hi all. I've got a weird tech problem I need help with. So, of course, I thought of y'all. I just set up a work at home PC laptop for my wife with dual monitors. The first is driven through a display port to DVI adapter. The second is driven from an HDMI port. Everything works fine when the PC is running. The first monitor is, in fact, a PC monitor. The second monitor is actually a TV. When the computer goes into standby or is shut down, the PC monitor goes into standby, which is fine. The TV, though, gets unhappy. It puts up a banner on the screen that flashes and moves around that says "no signal". There's a menu option that will turn off the TV after a certain amount of time with no signal. If I leave that on, and the TV turns off, it will not turn on again when the PC is restarted. If I disable the auto off function on the TV, which I can do, the TV just sits there with the "no signal" banner flashing all the time. Disabling auto off is the easiest thing to do, and the picture comes back on just fine when the PC is restarted. The TV doesn't care. I don't care TOO much. But it is a bit annoying. Since the TV has no standby function that I can find, I was wondering if you all know of some kind of adapter that could send a black or blank signal to the TV when the PC is not on. That way, the TV could stay on but it wouldn't be flashing the banner. My wife prefers not to have to switch the TV on and off every time the PC is turned on and off. It wouldn't be worth more than $ 30 or so to solve this. Otherwise, I can just ignore it. One other tidbit of information. Her old different computer was connected through a VGA port on a different docking station to the same TV. The TV never exhibited this behavior. I don't know if the port was somehow active all the time or what. I thought about sticking an HDMI to VGA adapter in the signal path just to see what would happen, but I don't know if it would work. Let me know what you think. All help is appreciated.

May your bits be stable and your interfaces be fast. :cool: Ron
 

rfrazier

Well-known member
Sep 30, 2020
482
138
Hi all. I think I've found a work around solution. However, I'd still like to know your suggestions if you have any.

I found an HDMI to VGA adapter lying around that's similar to this:

Moread HDMI to VGA with Audio, Gold-Plated Active HDMI to VGA Adapter (Male to Female) with Micro USB Power Cable & 3.5mm Audio Cable


So, I ran the HDMI output of the laptop through this adapter and connected to the VGA input of the TV like I had it originally before we changed out the PC. I turned the TV's auto turn off feature back on (IE auto turn off is active). Now, however, when the PC shuts down, and the monitor turns off, it does not display the annoying "no signal" banner. Also, when piping the signal to the VGA port on the TV instead of the HDMI port, the monitor comes back on when the PC comes back on. Go figure. I'm still getting 1920 x 1080 resolution so it's good enough for my purpose. Thought I'd pass it along in case it helps anyone.

May your bits be stable and your interfaces be fast. :cool: Ron
 

Sushi

Miso hungry
Sep 26, 2020
21
5
Sushi Bar, USA
Hey Ron,

I think I have a few more ideas on how to solve your problem. One major piece of info missing though is your computer hardware and TV model. I will try to give some ideas for multiple scenarios.

1. Newer GPU / Newer TV
They should both support CEC in which case you should be able to make a script that sends a CEC signal to the TV to turn it on and off automatically. Just Google (or Duck) about how to use CEC controls with a computer.

2. Older GPU / Newer TV
A CEC adapter should do a similar job as above. Something like this should do the job https://www.pulse-eight.com/p/104/usb-hdmi-cec-adapter
I would reach out to them with your specific scenario prior to ordering.

3. Older GPU / Older TV
Your solution is best.
 
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PHolder

Well-known member
Sep 16, 2020
969
2
402
Ontario, Canada
I'm assuming a simple bluetooth or WiFi or other "smart-ish" plug to just zap the TV off when not in use it too much of an annoyance? I used to have an X10 setup from RadioShack that woulda been great for this. A button on the desk beside you and switchable plug to the TV. For those too young to remember X10, here's a pic I "borrowed" off the net:
 

Sushi

Miso hungry
Sep 26, 2020
21
5
Sushi Bar, USA
I'm assuming a simple bluetooth or WiFi or other "smart-ish" plug to just zap the TV off when not in use it too much of an annoyance? I used to have an X10 setup from RadioShack that woulda been great for this. A button on the desk beside you and switchable plug to the TV.
Thought about that, but most TVs don’t have an option to return to previous power state after power failure, so figured it added more complexity for his wife.
 

rfrazier

Well-known member
Sep 30, 2020
482
138
The TV has a remote control. So, she COULD turn off the PC, then turn off the TV, then later turn on the TV, and turn on the PC. If you do that in the wrong order, the PC moves all the desktop icons to the wrong screen and scrambles them, although it may eventually put them back. So, she prefers to just punch the power button on the PC and have everything light up and work. At the end of the day, she just does a shutdown on the PC and walks away. That's apparently what's happening now that I've moved the #2 output back to the VGA port on the TV rather than the HDMI port and reactivated the TV's auto off feature. The change in behavior between the two computers surprised me, as did the different behavior of the TV when using the two different ports. I think it's the TV that caused the phenomenon. I think all the video ports on the PC go dormant during sleep or shutdown regardless. Regarding the CEC that @Sushi mentioned, the PC is a new or at least newish Dell laptop with a port replicator. But the TV is probably from 2015, and I don't think it has CEC. I was surprised that I couldn't find any cheap HDMI test pattern generators. I thought I would find something for $ 20 or so that would just send out a blank screen. But, I didn't. One idea I found on an AV forum from someone who was trying to do something somewhat similar is to use an HDMI "media player" that you can attach to a TV or monitor and run video from a memory card, etc. So, if my workaround hadn't worked, I could just record 10 hours of blackness in a video file, which could even be very low resolution. It might even be possible to record just 1 minute and have it loop somehow. I could run the PC's output and the media player's output into an HDMI splitter / combiner such that, if the PC's video was on, it would take priority over the media player ... I THINK. Kind of like what music on hold does for a phone. That would be starting to get pretty complex for a solution to what was just an annoyance. It's certainly been an interesting thought process to try to determine a solution though. I'm mentally noting all your suggestions, which I appreciate, in case I need them some time.

May your bits be stable and your interfaces be fast. :cool: Ron