Sega master system 2 rgb bypass - no video :(

[Tengugurl]

Hello!
i am trying to RGB bypass mod my North American SMS to no avail…

 

Tl;DR 

no documentation online on how to use a Voultar rgb pcb on an American SMS. Lots of documentation on PAL pcbs.

 

1) sourced RGB FROM R51, R55, and R53 respectively. Seen it pulled from the chip and also these spots

 

2) sourced Csync from 315-5246 chip as I have seen it pulled here before 

3) sourced 5v+ and GND from the 7805 voltage regulator 

 

 4) sourced audio from previous User RF spot (seen it pulled from here before)

 

5) grounded my mini Din connector to the GND on the pcb for good measure (also pulled GND from previous RF port) 

 

6) using a retro access Scart cable

 

7) drew out the mapping from the mini din female port to the legs I would solder to interface with it

 

8. Plugged it in and nada… nill…. Nothing 

got noise that’s not the game just sounds like audio noise from the power line

 

9) attempted to map/verify the scart cables pinout to the din (I.e does red 15 on scart equal red via the din) and I am noticing something strange…. The retro access cable is not mapping to the din. 
 

example: genesis 2 pinout says red goes to 

pin 9 but, when I go to pin 15 on the scart end, it doesn’t go to any of the pins on the din end of the scart?

 

so confused.

 

 

10) mapped out the din female and legs

*see attached  and it should work but it doesn’t?

 

 

any help or guidance would be amazing! Hope my list helps provide background on what I have done and tried

 

its like the din and sms is right but the Scart cable is not.

I can’t even get a multimeter to find the R,G,B and Csync on the scart cable. It works fine on genesis consoles? So I am even more confused 

 

Edited February 18, 2022 by Tengugurl

[Tengugurl]

More pics zoomed out

[Tengugurl]

[+-^CrossBow^-]

I've not installed the RGB bypass on any Sega systems myself personally. But I know that on the Genesis, they actually pull the RGB from directly off the main ASIC and I would assume it is the same on the SMS since the bypass board handles all the rest of the signals to the output side. The sync could be an issue as I believe that sync is TLL level on both SMS and Genesis systems. So if the display you are plugging it into doesn't accept TTL level and requires csync instead, then you might have to filter out the composite video and pull sync from the composite output? Last is to make sure that you have everything routed where it needs to go. You did show a pic of the Genesis 2 AV pinouts, but that is from looking at the plug off the back of the Genesis. So you have to remember to reverse everything when soldering it up on the actual mini din output. Since you didn't include a pic of that I can't confirm how you soldered it up on the output side.

 

[Tengugurl]

Good thinking @-^CrossBow^-

i am using the same din connector from a Sega genesis 2 that I bought from Console5 repairs.

 

I am using a csync cable with 75ohm on RGB.

 

I am pulling csync straight from the chip, not composite, didn’t put composite out on the din out, wonder if that would help? 
just looked at other people doing this mod and they don’t add composite, just csync.

 

i am half debating getting a frank strasser rgb pcb as I have seen 1 documented how to on that pcb and it worked.

 

bah, so close but no dice… one of the fun ups and downs of modding stuff

[Tengugurl]

Figured it out. Got a straight through pass through scart cable (Aka no caps or resistors in line) and now it works

 

solder points for ntsc sms =resistors per my pics and csync is on the chip towards the controller ports *see pics

 

aka those pics are accurate.

stating this as ntsc sms 2 rgb bypass pics and or instructions are hard to find