Roku 1 (2013) is fine with analog connections but I switched to HDMI port it strobes/flickers
I have a Roku one third generation. It has a great picture with the analog connections but i bought a Sony Bravia with HDMI and now when I use the ROku with HDMI it fickers or strobes. I bought two different HDMI cables to check. The TV is only 1080 but the cords were the newest cords. When I switch back to analog the picture is fine again. I tried two different HDMI ports on my TV as well. I only have one more to try, but wondering if the problem could be the HDMI port on my older Roku. It's never been used previously. This Roku has been flawless for 8 years and still is on analog connectors. And I love the analog audio out to my Sony theater Speakers.
Re: Roku 1 (2013) is fine with analog connections but I switched to HDMI port it strobes/flickers
Amazingly, your Roku is still officially supported, i.e. it still receives firmware updates. However, there are many, many newer channels that are not supported on that device (model 2710). It's possible the channel(s) you are using just have a problem with that old of a device.
As to your HDMI port, it's possible that there might be some dust within the port that is interfering with the connection. However, that usually appears as a simple non-connection, not a signal with "noise". Can't hurt to unplug the cable and blow it out.
Depending on the channels you wish to use, it might be time for an upgrade. However, Roku no longer offers any player with analog outputs. The last model with them was the Express+, model 3910. There are newer versions of the Express+, but they don't have analog connections.
Dan Roku Stick (3600), Ultra (4640), Ultra (4670), Ultra (4800), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.