N64 PAL image blanking/unstable, sync issue?

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    I do have an issue with my RGB modded PAL N64 in combination with OSSC.


    I have an RGB modded smoke grey PAL N64 (NUS-001(EUR), NUS-CPU(P)-02). The mod is the Universal Nintendo 64 RGB Mod with Integrated 3.3v Voltage Regulator from Arthrimus (based on Borti4938’s N64RGBv1 and 3.3v Voltage Regulator designs).
    I use Retro Gaming Cables’ Universal Super Nintendo PAL/NTSC GameCube PAL PACKAPUNCH RGB SCART cable (with csync) – connected to OSSC’s SCART input.
    The OSSC is connected via HDMI to an Onkyo PR-SC5509 A/V Controller, which outputs the video (set to “Through”) via HDMI to my TV (Sony KDL-65W855A). OSSC is on default/reset settings. TV and receiver are set to game mode, all “enhancements” turned off.


    The image occasionally seems to go black for a frame or two. When looking at a recording I can see that the image doesn’t go completely black, but rather seems to lose sync or something, messing up the horizontal and vertical position and other weird effects. Or the image gets darker with a wide, almost black horizontal bar. The LED stays green and the sync info doesn’t change (Prof.9, 288p, 313p, 540858).


    Hint: you can frame-step in youtube with . and ,

    frame 0
    frame 1
    frame 3
    frame 4

    Additional details:

    288p content from my PAL GameCube (forced 288p via Swiss), using the same cables and setup, works absolutely fine.
    Composite video from the N64 doesn’t show this issue either.

    I hope you can help me or point me into the right direction to try and fix this 🙂


    You need to test without the receiver between the OSSC and the TV.

    You said composite video did not show the issue. Did you connect the composite video cable to the component input on the OSSC?

    It looks like the TV keeps receiving correct sync because otherwise it would blank out for 2 seconds. It is probably caused by the RGB mod or receiver.


    Huh, okay – it works fine without the receiver. Well, I only get the sound from the TV, obviously, but the image seems to be stable.
    Component video without OSSC directly on the receiver works, that’s what I meant with that.


    I noticed that the issue is worst right after turning everything on. I’ve left the N64 running for a while and then turned on the OSSC and it was pretty bad right after turning it on. I also noticed that the sync info is slightly different, depending on when I push the button on the remote – it’s either Prof.9, 288p, 313p, 540858 or Prof.9, 288p, 313p, 540859.

    I don’t have an option to output a test image so I cannot try to adjust sync. The effect I get is very similar to turning up H-PLL Pre-Coast (or rather it makes it much worse).


    Here’s a comparison between 288p GC (perfect picture, no issues) and N64 (picture slightly blurry, mostly horizontal ghost image/blur towards the right border of the screen; sync? issues).
    Both are using Generic 4:3 Line2x mode.

    Prof.9 288p
    313p 540858 (or 840859)

    AV1: RGBS 313p
    15.62lHz 49.92Hz

    Prof.9 288p
    312p* 539415

    AV1: RGBS 312p
    15.62kHz 50.08Hz

    OSSC on-time (warmup) doesn’t seem to affect GC, but heavily affects N64 with flickering going down from every couple of frames to something like every couple of dozen seconds.

    Considering that this gets better over time, I’m wondering if there’s an issue with my OSSC. I usually associate such behaviour (issues improving or getting worse over run-time) with temperature or soldering issues. (To be fair, I don’t have that much confidence in the connectors because they have no strain relief, i.e. they are not anchored to the case, but all mechanical energy is directly transferred to the solder joints)

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