Help With db_electronics Triple Bypass on a Genesis 2 VA1

[samson7point1]

Installed the triple bypass pretty much exactly as pictured here:
https://twitter.com/leonkiriliuk/status ... 0756078594

This is on a Genesis 2 VA1 that previously had a Mega Amp installed.

When I connect everything up I get sound but no video. I'm pretty sure the sync signal is getting through because my gscartsw detects the system and switches to it.

I've double-checked the RGB input lines all the way back to the CPU and the input sync signal back to the video encoder. I've also verified all of the DIN connections to the bypass board.

Before installing the board, I trimmed all of the component legs flush to the underside of the board and covered it with Kapton tape. I cut the c-sync line leading to the DIN. On my board C32, C28, R47, R55, C30, R57, C29 and R56 were populated so I removed them. I did not originally lift the RGB pins from the encoder as the twitter poster indicated he had not done so.

To troubleshoot I tried, individually
- lifting the RGB pins on the encoder
- Replacing the 8 SMD components around the encoder
- Using an HDRetrovision cable
- Using an RGB SCART cable

Not sure what I'm missing but I figured I'd ask here in case someone has run across this.

[rama]

Is the CXA1145 still connected to RGB and/or CSync?

Remember that the chip wants to clamp RGB when CS is active.
I don't know if this needs to be handled though.

[samson7point1]

Is the CXA1145 still connected to RGB and/or CSync?

Remember that the chip wants to clamp RGB when CS is active.
I don't know if this needs to be handled though.

The chip is a MB3514. The RGB out pins have been disconnected, but the RGB input pins are still connected. The CSync input pin is still connected.
According to the datasheet the MB3514 doesn't have CSync output - apparently that's usually pin 11, but the MB3514 lists pin 11 as "NC".

[samson7point1]

Well, I found the problem, though I'm a little perplexed as to what caused it. For some reason the 5v line to the DIN was disconnected. Since I didn't cut or disconnect anything I'm not sure exactly why. I found a source for 5v, connected it to the triple-bypass and it fired right up.

Hopefully this will help someone else trying to figure this one out.