Commodore 64 S-Video to HDMI (Updated)
Updated: May 10, 2020
Update 05-10-20: I will be releasing a video comparing the HDMI converter used in this video with the RetroTINK 2X Pro recommended by so many of you. The new video is waiting on the 1541 Drive repair so I can do a more thorough comparison than just a blue text screen. In the meantime, I want people to be aware that they have other options. The HDMI converter works fine for me but you are displaying a 240p display on a 1080p screen. The RetroTINK doubles the resolution to 480p, and adds features like scanlines, so it's output is much better but at 4x the cost. If cost is an issue I would stick with the converter at $35, otherwise, the RetroTINK at $130 looks much better.
This post and video are based on a blog post by Ilkka Sjöstedt. I recommend looking at his blog post at Ilesj's blog.
I made an S-Video cable to connect the Commodore 64 to an HDMI monitor via an inexpensive HDMI Converter box. It works fairly well but I will be posting a followup once the RetroTink 2X Pro I have on order arrives. I will post side by side images from both so you can decide which solution is right for you. The converter is inexpensive and comes with both of the cables needed to make the customer S-Video cable but the RetroTink should have a much better picture.
The DIN connectors I used were pretty awful but I have not found anything better yet. They are standard 8-pin DINS so 2 pins must be clipped off to use them (see video). They have shallow cups to solder to and the plastic substrate is sensitive to heat. It tends to melt when soldering and the pins move out of alignment. I will include an Amazon link but recommend seeing if you can find something better.
The S-Video and Composite to HDMI converter I used does a fairly good job. A true upscaler would look better but at about 4 times the cost. As an added bonus it also comes with S-Video and Composite cables which can be used to make 2 Commodore 64 S-Video adapters. Amazon Link
In the near future, I will expand this post to include information on the RetroTink 2X Pro along with side by side image comparisons of it and the HDMI converter. In the meantime here is a link to a page with some options for finding one since, as of this writing, they are in short supply.