I used to have a famicom AV (grey model if you will) which played fine on my LCD screen TV.
I then got a very original famicom who got modified to output via RCA (yellow and white) and although the picture looks stable on a tube 90s TV, the picture is very painful to watch on my european lcd. The colors are here, no lags but you can find "rainbows" and sometimes the pictures looks it is split in two.....just impossible to play.
Whyy?
How was the mod done? Pictures? What cable are you using? AV cable only or with SCART adapter?
I will try to post some pics soon...I believe the guy who did substitute the rf for RCA cable. The cable is attached, you can't use a "normal" rca cable.
What model famicom is it? Board revision #? The serial number on the bottom will give me a pretty good idea if you've not opened it. At any rate with European TV's I'm not sure but with composite video I wouldn't think it would matter other than the 50hz and 60hz thing which is not the issue here anyways from your description. Sounds like issue with either a bad mod or worse yet a bad PPU or VRAM issue. Does every game do the same sort of thing on screen?
It is odd..because on my PAL tv, the picture was stable but in black and white and by playing via a PAL/NTSC converter, the picture does appear in color but is now not stable. With a test with the PC-engine, I can say the converter works (average quality but deliver the job).
The famicom mode has been quite bad to say the very least. I will try to post some info whenever I can (my famicom is in my basement now.....I can sell it for bargain of course).
Sounds like a bad AV-mod to me. But I don't know, PAL/NTSC converters produces strange results sometimes.
They do..this is my experience, but I know at leat it works for my pc engine. Image in color despite some lines which can bug the player.
But I just think the famicom had a sh**ty mode...Maybe I will try to re-mode it myself even though I am noob!