Got a tip that D-VHS would preserve the VBI to load TVGOS.
I searched and search this forum until I found "on the contrary" here apparently only the Older regular VCR VHS Tape preserved the TVGOS signals.
Which is somewhat interesting, and hopeful for any Newbies interested in (old tech). It means some of those really old VHS Tapes actually "preserved" the undocumented VBI signals that ROVI and Gemstar used to send out to set the clock and load programming guide grids into these DVR recorders.
After a VHS Tape is converted to Digital.. those signals I think would be wiped out.. but for old Tapes, the signals may still be retrievable.
I don't know what to do with the information, except it might be an interesting party trick to learn how to program a Raspberry PI or some small microcontroller that could set the clock on some of these really old recorders.. or it might be fun to look into what the VBI actually contained.
Not sure if this will help you but most of the TVGOS talk was going on over in the Sony DHG thread. https://www.avsforum.com/forum/42-hd...al-thread.html
Check the later pages of this monster thread, particularly posts by JoeKustra. Not sure if they ever tried to use a VHS tape to set the clocks on the DHGs or if it would have even been possible but that's where I'd start