This is one way of doing what you seek. You would connect the video signals to an AJA FS1 converter and you would get a standard definition or HD video interlace SDI video out. You would then capture that stable video signal with an AJA SDI capture device such as an AJA Io X3 or you would record those sequences to an AJA Ki Pro Ultra 12G video recorder (which you would then use to file transfer later your video to your computer.) The audio requires an audio cable adapter that connects the RCA audio outs of the VHS player to connect to the audio in of either the FS1 or the other AJA items.
That’s as portable as I can think of right now.
(This of course would be for an NTSC frame rate endeavor.)
Please remember that 50 Ohm BNC cables / RCA cables should not be used, but instead true 75 Ohm BNC video cables. By all means, do not use a regular RCA video cable between the VHS player and your video capture devices. RCA cables are all 50 Ohm cables and really do not have proper shielding for what you want to do. (RCA cables cannot protect you against RF interference generated by other devices nearby.)
I use a video switcher that has a composite in and outputs Serial Digital Component interlace SDI out. The switcher allows me to see a waveform monitor and Vectorscope of the incoming video which I use to correct the black level (usually sits around 7.5 IRE instead of 0 IRE,) Luma levels (usually sit around 107 IRE instead of under 100 IRE), and Hue. VHS pretty much all the time has the Hue off (usually takes on a purple toned shade). I color correct those in the switcher color corrector before I capture the video using an AJA capture device.
TBC(time base corrector) crystal sync (vertical and horizontal sync) VHS 4 head channel player with component out. best one is Panasonic AG-1980.
the recorder should be able to input component as composite/s-video are inferior like a Magewell Pro Capture HDMI. the recording format is important as well. something with 4:4:4 or 4:2:2 intraframe like prores, not interframe as interframe that isn’t recommended for fast motion. make sure you have interlacing fields setup correctly.
Just to add to what everyone else suggested… keep the video heads clean. Get a high quality video head cleaner and some Texwipes. Good head cleaners are highly toxic, so perhaps some gloves as well. The old tapes shed very easily and will clog the heads quickly. Also, be sure to capture the video as native interlaced NTSC (720×486). Then deinterlace and upscale it using something like Topaz Video Enhance AI (highly recommend).
The attached pic VHS player outputs in HDMi 1080p at 12-bit color. The attached pic 4K60 Card can capture 1080p 12-bit signals using the latest firmware. Tested to work via OBS. You must have a device between them that breaks HDMi copy protection, like an HDMi splitter or an HDFury device. I’ve used a few different splitters, but not all of them work. If you use and HDfury device, join their discord and contact their support team for custom firmwares.
After some research, I noticed the unit I mentioned does not play S-VHS in native S-VHS format, it plays them in VHS format, 240 lines instead of 400. If you use a native S-VHS unit with a S-video capture card, or s-video to hdmi, you should get the full 400 lines. I don’t know if any output hdmi though.