Sorry mate, the datasheet suggests that the RGB input is designed only for digital OSD input, not analog RGB.
Damn it. Does that mean I can't RGB mod it at all? Or I just have to give up the OSD?
Almost certainly. TVs of that era set all the inputs in non-volatile memory in the factory. If it wasn't designed to have an RGB input, that input will not be enabled in the settings. Those settings are non user-definable, they are set over an i2C bus with a ROM chip.
It could be possible to dump the existing ROM and reverse engineer the settings by decompiling the ROM and using the jungle IC's datasheet (assuming it's complete enough), but that would be an epic amount of work and it is both beyond the scope of this thread and outside of the wheelhouse of most of us here. You would need someone with a decent level of computer engineering skills and extensive experience with relatively outdated i2C programming
Of course, that's also assuming that there is even some unused RGB input on the jungle IC in the first place.
Delphius wrote: ↑Sat Jul 05, 2025 1:00 pm
Is the voltage steady at the injection point around 1.1 / 1.2v, and is the voltage from your external source 1.9v steady? If so, this would indicate you have DC bias so you will want to add a coupling capacitor in between your external source and the injection point. 1uf bipolar will probably work, but if you have polar ones point the positive end towards the higher voltage which seems to be external source at the moment. It probably won't hurt to have it anyway while you are testing. If there is a bias offset then I think it could also cause your display to go black when connecting.
The voltage at the injection point is ~1.2v pretty steady yes. External source is .7v. - when i inject, the resulting voltage is ~1.9-2v
I have tried direct but also tried a .1uf cap->75ohm resistor->injection point - same results both ways. Would a 1uf vs a .1uf cap make a difference there? I could try that as well
Delphius wrote: ↑Sat Jul 05, 2025 1:00 pm
Is the voltage steady at the injection point around 1.1 / 1.2v, and is the voltage from your external source 1.9v steady? If so, this would indicate you have DC bias so you will want to add a coupling capacitor in between your external source and the injection point. 1uf bipolar will probably work, but if you have polar ones point the positive end towards the higher voltage which seems to be external source at the moment. It probably won't hurt to have it anyway while you are testing. If there is a bias offset then I think it could also cause your display to go black when connecting.
The voltage at the injection point is ~1.2v pretty steady yes. External source is .7v. - when i inject, the resulting voltage is ~1.9-2v
I have tried direct but also tried a .1uf cap->75ohm resistor->injection point - same results both ways. Would a 1uf vs a .1uf cap make a difference there? I could try that as well
0.1uf is probably fine, or at least you would be getting an image if the biasing was an issue. I would still probably keep it on there while you are testing because it shouldn't hurt anything and if you are getting a steady ~1.2v at the injection point then this indicates it has bias. I would expect at this point that you would see at least some interaction with your external RGB though. Just to clarify, is your OSD affected when you are experimenting?
