Hello, gentlemen.
I hope this is the right place for this enquiry.
Before I try this improved firmware/mod, I wanted to make sure my GBS-8200 board itself works, and more specifically whether I can use it with my Model 2 Sega Mega Drive or not.
The latter is VA4 PAL MD2 board with a BH7326AF encoder chip and a region switch mod which works fine, but obviously loses all colour over composite output when switched to NTSC.
RGB would be a solution, but I want to connect to a VGA monitor, so here we are.
Unfortunately, the first try didn't go very well. Here's a video showing how the image jumps all over the place:
https://drive.google.com/open?id=1Mt2m0 ... irdUS688u_If I press the "Auto" button, the image stabilises for two or three seconds, then it's back to trampoline jumping.
Curiously, if I set the Vertical Position to anything less than 14 in the "Geometry" menu, I get this:
https://drive.google.com/open?id=1MqyLb ... q-Dxsdt6vxEven better, if I switch the input from RGBs to RGBHV I get "No Input" but then if I change the display resolution to anything else, I get a perfectly stable image but with wrong colours:
https://drive.google.com/open?id=1MxKip ... IXg_CHwr4PIf I manually adjust the trim pots adding lots of green and removing a bit of red, I get a slightly better display:
https://drive.google.com/open?id=1MtPm5 ... HoZ65DO_YHAlso, the "Geometry" menu is not accessible in this mode.
Even that however has lots of noise as you can see, but that might be because all the wires go to a prototyping board where I can easily swap resistors and capacitors at the minute.
In fact, this is what I tried:
- 680R on the CSync output from the console (that was my "default" setup).
- Using the composite video signal instead of CSync: no difference at all.
- 470R instead of 680R on CSync: no difference.
- 470R and a 22uF cap in series: no difference, but now the "Auto" button doesn't even make the LED flash. Same with different capacitor values between 10uF and 220uF, same with a bigger resistor.
- 1K ohm instead of 680, and no cap: no difference.
- 6 different power supplies to the GBS-8200: no difference.
Also, when in PAL mode the image is cut at the bottom if I select the RGBHV input, which as I mentioned has no settings where I can resize the picture.
I've noticed that others in this thread mentioned problems with a US Model 2 Genesis, but the solution seemed to be adjusting the values of resistor and capacitor on the CSync line. That doesn't seem to work for me.
So my fear is that even with a custom firmware I'm not going to get a usable display.
Any help or advice is hugely appreciated
