After three and a half years I can finally put this one to rest and purge it from my mind. Remember that ridiculous green line appearing on my Super Famicom? Well, it turns out things aren’t quite as straightforward as a faulty motherboard.

Here’s my Japanese Super Famicom with an SNS-CPU-GPM-02 motherboard. I’ve got plans to install an in-game reset modification and make the machine region-free, but first there’s this rather annoying video problem to deal with.

When I fire up Chrono Trigger, a green line appears across part of the picture. It isn’t there all the time, and depending on what’s happening on the screen it can be considerably more noticeable. Wonderful! That’s exactly what you want from a console that’s otherwise quite capable of working properly.

Naturally, my first thought was that something on the motherboard had failed. I’ve already been working on the console, so I swapped in another motherboard of the same revision. Surely that would get rid of the problem? Nope. The green line was still there.

I tried a different AV cable as well, with much the same result. Even Super Mario World shows the problem during certain parts of its startup sequence, particularly when the picture changes. At other times the image looks perfectly normal, which makes the whole thing rather frustrating.

After a bit of searching I found other people describing something similar, although the forum discussions I came across didn’t seem to have reached a useful conclusion. That’s the internet for you! A thread from years ago, somebody with exactly your problem, and no answer to be found.

There was still one obvious thing I hadn’t tried properly: another television. I’d been using the same Samsung TV for years, so perhaps it simply didn’t like something about the video signal coming from this particular Super Famicom motherboard revision.

Eventually I connected the console to a different television, a Hisense, and there it was. Or rather, there it wasn’t! The green line had disappeared. The picture was stretched into widescreen, which brought its own little annoyance, but at least I wasn’t staring at that awful line anymore.

So it appears to have been an interaction between this particular Super Famicom setup and the Samsung television, rather than something I could fix by swapping the motherboard or AV cable. I still don’t know exactly what caused the incompatibility, but I’m certainly pleased to have narrowed it down.

The Samsung TV I was using it on has also since died. Is that a little too convenient? It might just be.