Absolutely boggled with this one.
I have a 1-chip PAL SNES that I was previously having issues with. Taking the RGB output into my old CYP-based transcoder had some sync issues and since upgrading to an Audio Authority RGB to component transcoder I’d get a rolling picture. All my other consoles running in RGB look amazing however, even my Master System and 32X.
I figured the issue was around sync and saw the results of the SNES RGB bypass boards. I figured I’d knock out two things at one - fix the sync and make sure the RGB looks as good as it could be.
I grabbed a board a while ago from oldskool consoles which was based on borti’s design. I bought the one set to TTL sync (first mistake maybe?) and performed the prep work as described in borti’s documentation:
The symptoms are:
I’ve tested with my NTSC N64 RGB cable (same behaviour - no blue, but blue is coming through on the N64) and ran continuity checks along the scart connector back to check the blue signal, disconnected sync on the SCART cable to make sure I wasn’t getting confused with the pinouts (can confirm no sync resulted in no picture). I also cleaned up my soldering on the PCB compared to the above (which, despite the blurry image, had no continuity errors between pads in the initial fitting).
Thoughts from here -
I have a 1-chip PAL SNES that I was previously having issues with. Taking the RGB output into my old CYP-based transcoder had some sync issues and since upgrading to an Audio Authority RGB to component transcoder I’d get a rolling picture. All my other consoles running in RGB look amazing however, even my Master System and 32X.
I figured the issue was around sync and saw the results of the SNES RGB bypass boards. I figured I’d knock out two things at one - fix the sync and make sure the RGB looks as good as it could be.
I grabbed a board a while ago from oldskool consoles which was based on borti’s design. I bought the one set to TTL sync (first mistake maybe?) and performed the prep work as described in borti’s documentation:
- R15, R16 and R17 removed
- R28 and D1 removed (frees up pin 3 on the AV connector to use the CSync from the board for PAL systems)
- C11 replaced with a 470nF cap (value TBC - currently not able to check my parts!) to fix the ghosting issues
- Wires soldered to the nearby spots close to R15-16, and R28
- While not in Borti’s documentation, I upgraded the SNES’ main regulator to a 1.5A one and I also desoldered and removed the RF modulator. I had previously put in a decoupling cap on the regulator to fix the centre line issue and left that in there (one of the solid Panasonic ones recommended years back on Assembler to resolve that issue in another SNES console I used to have)
The symptoms are:
- No blue signal is coming through
- Sync seems stuffed - has trouble locking to the signal I think, you can see distortions in the screens attached. Black screens create a no signal error on my CRT
- Tried at both 50hz and 60hz
- Took apart the RGB cable and moved sync to pin 3 (stupid me at first didn’t change it - it was wired to composite sync!), and also moved to luma. Luma seemd a bit better than CSYNC off the bypass board in terms of not rolling the picture too much when the resolution seemed to change, but in practice once it locked onto the signal the screenshots are virtually the same as what I’ve attached
I’ve tested with my NTSC N64 RGB cable (same behaviour - no blue, but blue is coming through on the N64) and ran continuity checks along the scart connector back to check the blue signal, disconnected sync on the SCART cable to make sure I wasn’t getting confused with the pinouts (can confirm no sync resulted in no picture). I also cleaned up my soldering on the PCB compared to the above (which, despite the blurry image, had no continuity errors between pads in the initial fitting).
Thoughts from here -
- Any ideas if there’s an easy fix?
- Would the fact it’s TTL sync explain some of the issues? All my other consoles are not TTL, but the fact that it’s still bust when grabbing sync from luma has me double guessing this
- I didn’t do anything around the decoupling caps - is this worth investigating? I’m unsure if the bypass PCB has them fitted (I don’t think it does...)
- Borti’s documentation suggests I can grab the RGBS signals from the S-CPUN IC - is this worth a shot?
- Should I just break out my desoldering station and remove the current bypass PCB, grab a board from Videogame Perfection and have another go at it? He has a PAL-specific option so perhaps this will help
- Have I killed the SNES??