SNES on Commodore 1084S Monitor: RGB video scrolling/unsynced

[Arkanix38]

Im trying to make a custom RGB/S-Video system for my various systems (with a cable region switch) and as a proof of concept I need to test the RGB from my SNES on my Commodore 1084S monitor as it is the only RGB monitor I have. I've made a custom A/V breakout cable from my SNES to allow multiple A/V connections simultaneously.

I connected my breakout cable to the correct pins on an Amiga monitor cable and got the result below. I have checked that the R,G,B and GND are connected correctly and have full continuity from the monitor to the SNES A/V connector. Composite video is connected to C-SYNC on the monitor.


What could possibly be the issue here, do I need to use another syncing method?

[P]

No idea if it that helps, but RGB cables for PAL SNES usually uses the luma pin for synchro.

[Arkanix38]

Interesting, will try sync on luma and get back to you

EDIT: tried sync on luma (wired luma from console to C-SYNC on the RGB of the monitor) and got the same result. Good thing I checked the cable though, as i'd switched R and G signals.

Maybe I need a sync stripper?

Below, a very warped DKC2 title screen (got same result w/ luma and composite video)

[Pikkon]

Did you follow this?

[Arkanix38]

No, i'm not using a SCART connector as the monitor does not have a SCART interface. I got one of my old AV cables, pulled apart the AV connector and added pins for RGB and S-Video. I've directly wired R,G,B GND and Composite Video as Sync to the Monitors 9-pin RGB connection (ensuring that . I've ommited the pull down resistors on the RGB signal lines as i'm not too concerned with brightness yet, just getting a picture on screen. Considering the picture displays (albeit extremely distorted) i'd say that the Sync line isn't working as intended and most likely needs an LM1881 sync stripper on the Composite/Luma sync.

[P]

Hmm yeah I guess you need a stripper.

[Arkanix38]

Ordered a couple of LM1881 chips, will wire them up when they arrive and post results.

[narunetto]

I have the, I presume American version of the monitor and I wired up a SCART to DB-9 connector that was just straight passthrough and had no problems. I didn't use any sync strippers, caps, or resistors. It's been a long time and I've since dismantled that cable for a PVM SCART cable but it all worked fine. IIRC isn't there a v-sync and an h-sync knob on the monitor? Mines in storage right now so I can't take a look.

[Arkanix38]

There are V-Phase and H-Phase knobs but these do not appear to help. On S-Video and Composite they shift the position of the screen and for RGB they appear to slightly change the scrolling pattern (emphasis on slightly). I've heard of PAL consoles distinctly requiring a sync stripper in some applications, but we'll see when the chips get here. They weren't too expensive so if they don't work its no fuss.

Besides, it'll give me an excuse to get the Oscilloscope out

[Arkanix38]

Wired up my LM1881 and no dice, picture still unsynced. Tried using my scope and looks like the Sync output is lower voltage than the Composite video. Might have to try switching LM1881's as I MAY have accidentally fed +12V instead of Composite Video

[Arkanix38]

Ok tried building the LM1881 circuit again and had minor success. My NESRGB modded AV Famicom works on the screen using both NESRBG C-SYNC and with the sync signal stripped from Luma using the LM1881.

This does NOT work with the SNES however. Is it time to just modify the SNES to output C-Sync directly from the video circuitry to the Multi-Out connector?
Post Merge: August 11, 2016, 03:00:14 am
Never mind, got it working!

[mikewolf78]

Hi, I know it's been two years since last post in this thread but... could you share your solution?
I'm struggling with a the same problem.