Thank you for both trying to be civil. It can get frustrating when a new member pokes their head up and makes a ton of threads which probably could have been done in two. Most of us have done it ourselves, i certainly have in a few places so i'm not judging, just pointing out it doesn't stop you shaking your head each time it happens. And enough ppl hhelped us that we'd like to be able to pass the favour along
abispac, if i understand what you're asking correctly...
Most but not all CRT-TV's with an On-Screen-Display (OSD, being the channel number or volume coming up one the screen itself) can be hacked to take an RGB input if they do not already have one. This is often a straightforward process, but it does involve a bit of reading and figuring things out. The gist of it is that you find a likely candidate set, google the model number to find the service manual and examine the schematics around the jungle chip (main video and deflection chip) and the micom (microcontroller that displays the OSD and remembers things like language and volume settings when the set is off). If you can't find the service manual, open the set and read off the models of the two largest IC's and google their datasheets.
Usually the micom will feed RGB and a blanking signal into the jungle chip (and sync if no external source is connected, but nevermind that). The blanking pin is often called Y or blk or a few other things, and is usually next to the RGB input pins on the jungle. Blanking turns off other inputs to the jungle chip, allowing the signals coming into the RGB inputs to be the only ones output to the display. To display your RGB signal, you connect ~3.5V to the blanking pin (from 3V to 5V should work, and can often be found nearby on the chassis, or from your video source) and then connect your RGB signals, sometimes through small capacitors to remove any DC bias. Sync goes into the composite-video port where you used to plug in your yellow AV cable.
The best place to look into the above is the shmups RGB hacking thread. There are mods recorded for a hundred sets at least on there. You will certainly want to look into MarkOZLAD's OSD mux method as this means you can keep the OSD fully working and use your RGB at the same time, no need for a switch or anything.
https://shmups.system11.org/viewtopic.php?f=6&t=56155So far, so good. With a PC source outputting 15kHz (yes, crt_emudriver is by far the best tool for this if you're on Windows 10) you would simply plug in your 0.7Vp-p standard RGBS from your PC, perhaps with 75R terminations if needed. The ArcadeOSD and VMM utilities in crt_emudriver will allow you to adjust your modelines to the horizontal size and position required. Most sets have H-pos but not H-size adjustments, so this feature is really nice.
An Arcade board outputs RGBS at higher levels, normally 2 to 4V peak-to-peak. These levels can be attenuated using resistors or possibly something like a THS7314/7316/7374 amp used as a line driver, to get the 0.7Vp-p or in some cases 0.5Vp-p the jungle chip expects. And you won't be able to adjust the horizontal size if the TV doesn't have that ability - the service manual of most sets will list the items in the service menu, so you might be able to check.
It must be possible to modify the horizontal scan of any set, but I'm not sure what the principle is. I've only looked at it briefly. Modifying the vertical size is much easier to fudge, but most sets have this option in the service menu anyway. Just make sure you have the remote for any set you want to try, and can get into the service menu.