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RGB Mod TV - Jumping off point
Alaska:
I have been looking into modding a TV to accept RGB for awhile now. I am new to the topic but have come across some helpful links that provide details regarding this mod. I hope these links help others find a jumping off point if they are interested in doing an RGB mod. Anyone who has anything to add, please comment below!
Background info on RGB.
https://www.retrorgb.com/rgbguide.html
Ton of builds and Q&As
https://shmups.system11.org/viewtopic.php?f=6&t=561551
In Search of Scanlines: The Best CRT Monitor for Retro Gaming ~ Article by Wesley Fenlon
https://www.tested.com/tech/gaming/456719-best-crt-retro-games/
Videos on RGB mods
Part 1
Part 2 - VGA input
Sony Trinitron Mod using Closed Caption
Sony Mod with locked BLK
https://www.instagram.com/p/B7OIe0lBHzG/?igshid=1w1sa8xyjemlv
NTSC TV RGB Input Hack ~Michael Moffit
http://mikejmoffitt.com/articles/0032-tvrgb.html]http://mikejmoffitt.com/articles/0032-tvrgb.html]http://mikejmoffitt.com/articles/0032-tvrgb.html
DIY circuit to convert VGA to composite sync
https://www.epanorama.net/circuits/vga2rgbs.html
Another solution presented below - use separate 500R resitors and 1k potentiometers for the H and V sync, then combine and connect to composite input
Types of RGB Mods:
Feed RGB to an unused/extra input in the Jungle Chip that is not associated with the on screen display (OSD). Example in the third video above where the closed caption board was modified to dish RGB from a console into the Jungle. RGB input must be analog!
Feed RGB through the OSD to the Jungle IC. This is a bit more involved as you will have to enable the OSD by feeding a constant voltage (typically 5V) through the blanking line associated with the OSD. Otherwise your RGB will show up inside of the OSD lettering. Also, a toggle switch will likely be needed to enable the OSD to make screen adjustments. This can be done using a 4pdt switch (4 inputs, three lines, RGB + BLK for your feed and the native OSD).
Feed directly to the neckboard. This is not optimal and not for noobs. It is much easier to find a different CRT than attempt this hack unless you are very experienced in TV repair and have the proper equipment.
buttersoft:
The best place to go for RGb-modding advice is hands-down the shmups thread. There's a like 90 pages, but it will answer every question, and if not you can ask politely and get an answer
https://shmups.system11.org/viewtopic.php?f=6&t=56155
IT's actually easier to feed RGB straight to the neckboard than anything else, but still not recommended as if you do it wrong you're nonstop dosing yourself with x-rays.
EDIT: Alright, my detector was faulty. Luke Evans Simon has pretty much proved how hard it is to increase x-ray production. Using a neckboard mod is still a second-best option though, as it bypasses HV regulation which can leave to funny thing happening to the picture like line droop and field tilt (sic).
Also, that sync combiner is unnecessarily complex. Easiest is simply to use crt_emudriver and output composite sync directly from your GPU. After that, using a 500R resistor and a 1k potentiometer in each line, then combining the two, is all that's needed. There are edges cases, but 99% of the time that will work perfectly.
nipsmg:
The vast, vast majority of mods (especially on US NTSC TVs) will be leveraging the OSD Mux method. By far, the easiest chassis to mod is the BA-5D chassis (Trinitron KV-FS100, KV-FS210, KV-FV300, KV-FV310. These were popular TVs and show up often for cheap. The mod requires you to remove the board, take off some very small surface mount resistors, then everything else is just soldering to completely exposed topside jumpers. No pulling legs of resistors or capacitors, no other mods to the board or existing components.
Here is my mod with detailed instructions:
https://shmups.system11.org/viewtopic.php?f=6&t=63622&start=78
Note, read up on discharging tubes. It’s really not very hard, but make absolutely sure you do it and do it two or 3 times just to be safe. Once you get that, the rest is easy.
Alaska:
--- Quote from: buttersoft on January 30, 2020, 08:45:21 pm ---Also, that sync combiner is unnecessarily complex. Easiest is simply to use crt_emudriver and output composite sync directly from your GPU. After that, using a 500R resistor and a 1k potentiometer in each line, then combining the two, is all that's needed. There are edges cases, but 99% of the time that will work perfectly.
--- End quote ---
Thanks! Essentially if someone wants to combine syncs, they would need to run H and V sync individually from the VGA leads to their own 500 ohm resistor then to a1k potentiometer (three leads, input sync with resitor, output, gnd), then combine the leads and connect the composite signal the composite input? Genius as this would allow for the signal to be 'tuned' in case there is a discrepancy in resistance or voltage.
buttersoft:
Yes, something like that. Most of the time tuning isn't needed, but occasionally it helps. And extron or similar device will do the same job easier, but is much more expensive to start with.