Hello Everyone !
This is a good news thread ! With a successful Rgb Mod
Firstly want to thanks all the envolved people that helped with hints and tips, but the special thanks goes to Mark, without him this mod will not suceed, he provides so much detailed information, from where to get the right connections, and help me sometimes to avoid loose the chassi with precious information. Will try to describe bellow, and try to update this thread once on a while if i forgot something to help another guys that should have the same TV set i have.
So this mod were made onto a TV 21" Philips 21Gx1669/78r, Mark has found a very easy way to inject the rgb signal direct onto a "NOTUSED J281" port on the board, some kind of sleep port, so spare me from lift the tiny legs directly on the chip, turn a much easy task to do, this particular J281 has all the inputs you will need (red, green, blue, gnd, and f blank) the sync was get from the AV port.
You will need:
2 pçs = 1k ohms 1/4w
3 pçs = 75ohms 1/4w
1 pot = 10k type B
Vga cable (in my case used a Revenge from Mars db15 male on one point and a pin 10 wells garner default, on the other point)
Remember this mod will work only if you have a PC, with already 15khz output, i used an ATI 5450 patched, Winxp 32bit + CRT_Emudriver + Groovymame (crt special version)
You will need to run the sync from the vga (h and V), and before twist them you will need to install a 1k resistor in each wire, them twist and wire to the AV connector central pin, grounded 3 resistor 75ohms in each color with the same gnd that goes to pin 1 J281
On the middle of the process we change the 5v source, not anymore from J390 pin 3, and now from the BC337 7290 transistor leg "C" this one provides the right stabble 5v we needed.
But when turn on the tv, ,the screen goes black, so we need to add a potentiometer 10k type B, on any external leg you put the 5v source, and in the middle leg you install the wire that will go to the F Blank (purple wire).
I have a google drive with all test and photos so people can see what i´v done, and will update this album with frequency, so stay tunned!
https://photos.app.goo.gl/ROlDzMpabIOwCrV42Sorry for some mistakes on English write and specialy on speach, lol
Now will restore the OSD wires cutted so i can adjust the vertical size, and horizontal position of the picture thru the service menu.
Things to to in the future:
- Replace those fast connectors with better shield wires, those installed are so thin, have to put some shield wires because a little bit interferance appears sometimes, just on solid colors background you see that, but nothing that overcome the beaulty of the picture.
- Maybe rip off one side of a VGA quality cable an solder direct those wires in the board, take off all crapy low quality wires, with already on vga cable ones, to avoid any kind of interferance.
And Mark thank you again my friend!
Marcos