HDMI via 20m cable to TV - 1 laptop ok, other not ok

[jimotoole]

We have two laptops - both HP-15s models. One was purchased about 12 months ago, the other last week. The older one of the laptops connects to a TV via a 20m HDMI cable - works fine. When the newer one is connected the TV displays "No signal". However, if I look at the sound devices in Settings, I can see the Realtek Audio and the TV audio devices. I have tried adding a HDMI Extender but still no connectivity. If I use a shorter cable, it connects to the TV fine as well as to other devices such as an Epson projector.

I feel therefore that cable length could well be the problem but I don't understand why one machine connects and the other doesn't when they are the same spec. The 20m cable has an amplifier in it.

[banhien]

@jimotoole 

Do you use SAME cable ? Are BOTH computers the same model ? (not all 15s machines are the same) . Depending on HDMI port (actually machine), they can transmit longer or shorter.

More information:

              https://cie-group.com/how-to-av/videos-and-blogs/distance-of-hdmi-signal-travel

Regards.

[jimotoole]

Yes - same cable.

The computers are different in that one identifies as HP Notebook - 15s-du1016tu and the other as HP Laptop 15s-du3605TU but both are 15s models albeit one is 12 months or so older. It would seem to me that the hardware/HDMI port is different in that the newer one we are having trouble with is unable to generate sufficient signal over that distance even when a HDMI Extender is added. I guess the simplest answer is to return it and exchange for a model that works over the distance - but it is disappointing that machines sold with the same model number can be so different. I actually would have expected the newer machine to out perform the older one.

[ITTim4u]

I have the same question too.  Mine is a little different.  If I use a non powered travel docking station that is connected to the 20 ft cable to the meeting room panel I am able to project the laptop screen.  If I don't use that docking station it will not project to the meeting room screen.  Also if I connect the 20 ft cable directly to the meeting room monitor is works.  If I use a standard 6 foot cable to the meeting room panel the laptop projects to the meeting room screens.  None of my Dell Latitudes have this issue. 

[jimotoole]

I returned the newer computer and swapped it for a Lenovo of the same spec (and saved $50) and all good. I wasn't brave enough to try another HP 15s but all is good with the Lenovo.