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SNES sync issues after mod

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This topic contains 43 replies, has 7 voices, and was last updated by  Voultar 4 weeks, 1 day ago.

Viewing 15 posts - 1 through 15 (of 44 total)
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  • #14513

    blackice85
    Participant

    Hi, I’m having some sync issues with my SNES after getting it back from Voultar for a newer RGB mod. Are there any specific settings that might help here? The resolution jumps from 261 to 262p rapidly, along with the frequency 60.05Hz to 6.24Hz. Before sending it out I never had to mess with anything, hopefully there’s a fix for this.

    #14519

    BuckoA51
    Keymaster

    Are you on the latest OSSC firmware ? (0.78)

    #14520

    blackice85
    Participant

    Yeah. I was on 0.77 (and earlier) where it worked previously, and upgraded to 0.78 while it was out for modding. First thing I did after seeing it not work was to try downgrading back to 0.77. For the sake of troubleshooting I can change it back to 0.78 though.

    #14522

    marqs
    Participant

    Any details about original and new mod?

    #14527

    blackice85
    Participant

    Original mod was a simple 3-wire style DIY that used it’s own amp, the new one is the THS7374 amp installed by Voultar.

    http://voultar.com/index.php?route=product/category&path=60_62

    Seems like it syncs to the display less often when the AV receiver is in the mix, but previously it didn’t care.

    #14528

    blackice85
    Participant

    I think I found what it was, it was line doubling that it doesn’t like now. It’ll still sync up most of the time with linex3 and x4, but not linex2. I knew the higher linex modes aren’t compatible with all displays, but I didn’t think to check that the lowest was no longer compatible.

    Maybe the new refresh rate combined with the odd resolution pushed it out of the acceptable range?

    #14540

    paulb_nl
    Participant

    Are you using a CSYNC cable and is the new mod set to 75Ohm CSYNC or TTL CSYNC?

    #14542

    blackice85
    Participant

    Yeah it’s a CSYNC cable from retrogamingcables.co.uk

    As for the mod, I don’t know offhand. It looks like it can be set to either by setting a jumper, so I’ll have to open it up later to see.

    Presently, it’ll sync up 99% of the time if I turn it on, and then reset the SNES after a few seconds. Seems like it settles on a stable frequency somehow. Not sure why resetting it works, but that seems to fix it, just powering it on is hit or miss.

    #14543

    eric90000
    Participant

    I’m fairly certain Voultar sets his boards by default to attenuated 75Ω CSync.

    I’d be willing to bet that the cable you’re using, also has attenuation built in (resistor on sync line), in order to bring the SNES TTL CSync output level down to 75Ω terminations.

    So if these two are the case, you might be attenuating the sync signal twice, which could explain your issues? Voultar told me that if you’re using his board with 75Ω jumper on, then make sure there’s no resistor on the sync line in the SCART head on the cable.

    Hope this helps

    • This reply was modified 1 month ago by  eric90000.
    #14546

    blackice85
    Participant

    Ah, so it could be as simple as just switching the jumper then? Seems like an easy thing to test for, I’ll do that later then.

    #14547

    eric90000
    Participant

    It’s certainly worth a try. First thing to do is to pop open the SCART head and check if there is a resistor on the Csync line. If there is, then jump the TTL on Voultars board. Just be careful and make sure you don’t end up sending TTL level straight to your OSSC. This can put added strain on it and reduce it’s life span.

    #14549

    paulb_nl
    Participant

    @eric90000 Thats what I was also thinking. Voultar setting his boards by default to 75 Ohm CSYNC doesn’t make any sense. All CSYNC SNES cables sold should have the 330 Ohm resistor in them and its dangerous to use a cable without components on the sync line if you connect it to an unmodded SNES by mistake.

    #14551

    eric90000
    Participant

    Yep that’s true. I wonder though, does Voultars TTL sync output level match that of a stock SNES? Do you reckon that:

    Voultar TTL setting > SCART cable with 330-450 ohm resistor on the csync line

    is the same as:

    Voultar 75Ω setting > SCART cable with NO resistor on the sync line

    I’d love to know if both output levels are within acceptable and safe range?

    If anyone hasn’t seen it, Bob from RetroRGB has a pretty helpful page on his site with Csync info, as well as a pretty helpful video: http://www.retrorgb.com/csync.html

    #14552

    blackice85
    Participant

    Yep looks like I got a resistor in my cable, so I’ll open up the console next and see what it’s set to.

    Edit: Looks like the TTL jumper is shorted, so that’s right as far as I understand it.

    • This reply was modified 1 month ago by  blackice85.
    #14555

    blackice85
    Participant

    I’m including a video link of what it does when it decides to act up, in case that’s helpful.

    https://drive.google.com/open?id=0BzqLju9MJloEczRYNTN5Qm10QUE

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