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OK so I have a Philips TS2774-C101 (F8 chassis). It should be a candidate for RGB mux mod, with a SAA5565 micro controller and a TDA8844 jungle IC. I have done a mux mod already on a well-documented Sony, so I am not a complete noob, but pretty close...
I got the wiring done of this Philips. I relied heavily on MarkOZLAD's recommendations (thank you!) for the E8 chassis here:
https://shmups.system11.org/viewtopic.php?f=6&t=69578&start=37Steps:
1. Remove surface mounted resistors at 3675, 3676 and 3677.
2. At 6603, 6604 and 6605 insert 680R resistor and then a 1N4148 diode on each of these RGB lines. (Resistor closest to micon, then the diode pointed away from micon toward the jungle.)
3. Leverage the unused J209 header. 5 pin header for R,G,B, blanking and ground (pins 1 through 5, respectively). We will use this to feed in our external RGB and blanking. You need to put the pins in yourself, .1" 5 pin.
4. The F8 schematic is odd. It shows 100Rs at 3231 (red), 3232 (green) and 3233 (blue) coming out of the header. Elsewhere in the same document it lists zero-ohm resistors in those spots. On my actual PCB, there were no components there at all. They were all gaps that needed to be bridged. So I bridged the gaps to complete the lines from the header pins to the jungle. I put 270Rs on each of these lines.
5. For the external RGB lines to feed to the appropriate header pins, do the usual where you have your color lines basically branching, one branch going straight to the correct pin, the other branch connecting to ground through a 75R.
6. For blanking, I took ~3V from the leg of a capacitor I believe is 2600 (a 22uF cap), to a switch, through a 75R and to pin 4 on J209. You can probably find a better spot to connect than that pin, it works for my design though.
7. For sync I just fed sync into the composite video input.
This works... I haven't buttoned it all up nicely and haven't even tested RGB simultaneously, but I tested each color. Fairly confident the wiring I described above will not change. I am waiting for a couple more parts before I am 100% finished.
R
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