I've been trying since New Year's to make a general-purpose RGB>YPbPr encoder (and hopefully refining the result to also output S-Video and Composite) with basically no usable results. The end goal here is to have a small and simple circuit board that I could build into various consoles or into plug-and-play dongles to get my YPbPr CRT working with the Dreamcast, PS1, a PC that I built to be a console-ized arcade emulator and what have you.
My most recent attempt focuses on the Snes' encoder, the S-ENC or BA6592F. I've found this schematic and I've been working from it, but I'm getting absolutely no picture from it. I've seen a few people talk about it here and I was hoping that someone could tell me what I need to do to this chip to get it to work.
Right now my setup is
Composite sync from Dreamcast > 22uF capacitor (remove DC coupling) > 75Ohm pulldown resistor > pin 8
+5V from the Dreamcast > 0.047uF capacitor to ground > 10uF capacitor to ground > pin 5
Ground from Dreamcast > pin 2
And if I understand at all how this thing works, I should get an empty sync signal out of pin 23. But instead, I get a very flat 1.4ish volts out of pin 23. Now, there is a lot of pins on this chip that I don't at all understand. Here's what I've got out of it:
Code: Select all
01 - Pr Out 02 - GND 03 - PCP? tied to bfp? 04 - SW - power off chip? Tied to VCC in SNES schematics 05 - VCC 06 - Chroma out 07 - Composite out 08 - Combined sync in 09 - Luma in? connects to 23 indirectly 10 - Pb in? connects to 24 indirectly 11 - Pr in? connects to 1 indirectly 12 - Blanking? - 10kOhm to ground in the SNES schematic 13 - volt c...? 14 - volt b...? indirectly tied to 13 15 - volt a...? 16 - Burst flag pulse? 17 - pha? 18 - pdo? 19 - NTSC/Pal switch tied to VCC in SNES schematic 20 - Analog Red in 21 - Analog Green in 22 - Analog Blue in 23 - Luma out 24 - Pb out
I've tried a few other configurations by tying VCC to a few different pins but none of it seems to have effect on my Luma line. Does anyone here have any experience with this thing?