February 4, 2018 at 3:57 PM #18988
I’ve got a slight problem with the OSSC and my japanese model 2 Sega Saturn:
The system keeps loosing sync. At starting point my console shows up the screen with the setup for date and time just fine, but after loading a game the picture changes rapidly between black screen and game screen. The LED on the OSSC shows for most of the time 263p/59,82Hz, but that keeps changing to slightly different specs.
I use a cable from thefoo.83 (like this: https://www.ebay.de/itm/Sega-Saturn-RGB-SCART-EURO-HQ-Cable-CSYNC-CLEAN-SYNC-Cable-for-all-consoles/173133509200?hash=item284f8fb250:g:QrEAAOSw44BYRCRa), which works just fine plugged directly into a TV. So I assume the cable is not at fault here? Before that, I used a noname RGB Saturn cable, which did not have the sync issues (but after some time only displayed yellowish colors and in the end quite literally just fell apart). All of my other consoles (PAL Dreamcast, JAP N64, PAL SNES, PAL WII) work just fine with every output mode of the OSSC (even the PAL SNES).
Do you think it might be the sync stripper used in the cable from thefoo.83 in combination with my console which causes the problems? Any ideas?February 5, 2018 at 2:55 AM #19005
Sync strippers have been known to cause problems when they aren’t needed, like with the OSSC or the gscartsw_lite. You really only need a sync stripper if you’re using a PVM or BVM; and, if you’re using a gscartsw_lite, that has one built in.
Frankly, CSync cables with a sync stripper in the SCART head don’t make sense to me (except when connecting a console directly to a display that will only take CSync); half the reason of using CSync over luma or CVBS is to reduce interference, but the sync strippers in these cables are on the other end of the cable, after the interference would be introduced. :/February 5, 2018 at 10:22 AM #19007
This particular cable has the stripper in a little box close to the console side, so it would actually help with interference along the cable. Also don’t forget that some SCART switches like the popular Bandridge ones have some issues with composite video bleeding into RGB, a SCART head mounted sync stripper for my only sync-on-composite console (GC) made a real difference.
Obviously, like you said, a sync stripper makes little sense for a console that natively outputs proper csync. I can only imagine this cable was designed to provide csync on both NTSC & PAL Saturns, the latter lacking native csync.
One problem with cables from this seller seems to be that, at least for a while, he omitted the 470 ohm resistor after the sync stripper. This means this cable might be outputting a dangerous TTL-level sync signal, causing everything from incompatibility to equipment failure. You could inspect the cable (likely need to remove some hot glue in the stripper box) and/or contact the seller. I’d recommend a cable from retrogamingcables.co.uk in any case.February 5, 2018 at 10:45 PM #19026
Yeah there really is no need to add sync strippers to consoles where clean sync is available anyway. Disappointing that thefoo.83 has decided to start doing this. I suppose it makes the cable universally compatible but still, would have made more sense to take luma for sync in most applications.February 6, 2018 at 1:19 PM #19050
Hey, thanks for your help. I took a look at the cable and the 470 ohm resistor as well as the 220uF capacitor seem to be present on the csync line in the SCART head. So my setup obviously just doesn’t like the sync stripper. Which is a bummer, because otherwise the cable from thefoo.83 is really well made.
Well anyway, I’ll buy a cable from retrogamingcables.co.uk and see if that works better.February 6, 2018 at 5:28 PM #19054
Did you make sure the resistor is actually 470 Ohm and not something like 75 Ohm? I don’t know if the sync stripper is a LM1881 but I have never seen a 220uF on the LM1881 output. Thats only needed on the Saturns real CSYNC line.
Is it possible to post a picture of the sync stripper in the cable?February 6, 2018 at 9:31 PM #19072
When I spoke with thefoo.83 about my cable he told me that he is now putting 470 ohm and a 220uF cap on the sync line. I also don’t think the 220uF should be there. So I don’t think spritti made a mistake, the SCART head should be empty otherwise (ok, maybe one more resistor).
My cable did not have the 470 ohm resistor but the picture with the OSSC was looking just fine. I added the 470 ohm resistor into the SCART head and did a quick test with my ‘lab’ TV and got a rolling picture. Hm, weird. Maybe I messed something up when removing the hot glue from the stripper box. I accidentally disconnected the sync line from the LM1881 input through the cap, but soldered it back in place, did continuity checks and everything that ought to be / not to be connected was correct. I didn’t want to mess much more with it since I didn’t want to risk to continue using a cable that was wrong and I didn’t understand 100%, very happy with my RGC csync cable now. But still, would’ve loved to understand the issue, just for my own education.
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