Nah, thank you for doing the community a service, its not like you have to reply to everyone asking for help, so really appreciate it.matt wrote:Sorry I missed this when you posted it. Always nice to see other people here from Hawaii. What island are you on? I've done a number of RGB mods and am happy to help if you're on Oahu.
Here's the data sheet for your jungle chip if you didn't find it already:
https://datasheetspdf.com/pdf/610984/Re ... 61251AFP/1
It's very similar to the jungle chips used by the Toshiba AF series, which usually do well with RGB mods and have been documented pretty well. The chip can be set to take digital or analog RGB, but fortunately the schematic looks like a typical circuit for analog inputs so I think it would work. The usual OSD mix method should work fine. Have you looked up MarkOZLad's posts on the subject?
I don't think this is out of the ordinary. According to its data sheet, the jungle chip expects 0.7pp RGB in analog mode and 1vpp for digital. 2.3v on the input is pretty normal for OSD signals, and I think the 0v on the Micon outputs is an irregularity with the schematic.vol.2 wrote: What I see on the schematic is Zero Volts DC coming out of the OSD output on the character generation chip and roughly 2.3VDC on the OSD inputs on the Jungle IC. I also do not see any DC restoration circuit in between the two lines, or a level shift chip. I see 2.3VDC coming out of the Jungle IC RGB outputs that are going to the neck board. That might suggest that the OSD is directly coupled to the RGB output and the RGB input voltage level simply reflects the output voltage level (because they are just joined at that point) and the caps and resistors between the Char Gen IC and the Jungle IC are there to just block the DC offset in the direction of the character IC.
I actually am on Oahu. I have read through quite a bit of this thread, and while I do get the circuit that needs to be built, I have no idea how you guys determine when and where you need resistors or capacitors, and at what values, and what they even do for the circuit as far as its relation to the signal. I have seen that spec sheet for the Renesas chip before, and other than the pinouts, I wasn't able to absorb much from it.
Though with the information you gave me, I now think I figured out how to use MarkOZLad's resistor chart. Looks like ill need to
Remove the 330ohm resistors to ground for RGB
Add 180ohm resistors in series after the 330ohm resistors on the RGB lines
add 75ohm resistors to ground before the 180ohm resistors
Hoping I'm right here. Would I be getting sync on composite? And as for the blanking voltage, how much and would it be before or after the 560 ohm resistor? I've reviewed some Toshiba AF series RGB mods (from The SegaHolic and Analog Thinker, specifically) but not sure if I should be using the same reference voltages they used on their Toshiba sets.