Shiozaki wrote:
Hello everyone, I've since my last post set the other CRT aside and start working on this RCA model E13320, i really like the look of this one, and looking at the schematics it looks promising.
So if I'm understanding right I need to:
1. lift one leg of resistors RR41-RR38
2. Per the mux chat, since the factory inline resistors are 3.3ohms and there's no diode add 470ohm in the empty holes for RGB input mux.
3. remove the factor resistors to ground at RR534-RR537.
4 from Scart need RGB 75 resistor to ground, fast blanking needs factory value to ground (still new to this, reading values i haven't figured out, what is 820RO?)
5. feed-in RGB signal between the 3.3 and 470 resistors.
6. possibly change capacitors at CV505 CV507 CV509 to 100nfs.
The only thing I don't understand is what protects the microcontroller from getting 5v on the fast blanking pin without a switch, don't you add a diode or something?
Does this sound like I've got the right ideal or am I missing something?
service manualschematic and picturesYou're looking in the right places but you are a bit off.
You don't want to lift the legs of R38, R39 and R40. They just remain there unchanged.
If you want to use the twist method like the 8 Bit Guy you want to remove resistors RR535, RR536 and RR537. You will replace each of these with 470R and 75R twisted together and soldered back into the holes of the resistors you just removed. The leg of the 75R will go into the hole that is grounded, the leg of the 470R will go into the other hole. The RGB will be injected into the legs that are twisted together. The 75R in the twisted resistors becomes your termination, no need to add more at the scart port.
Note that this assumes that RR535, RR536 and RR537 are through hole type resistors.
I wouldn't change the caps CV505 CV507 CV509 unless you have issues.
For blanking you can use the method the 8 Bit Guy uses in part II of his video. Lift the leg of RR41, solder a wire from the hole left by lifting the resistor to the outside leg of a SDPT switch. Run a 5V line to the other leg of the SPDT switch and then run a wire from the middle pin of the switch to the leg of RR41 that you lifted.