Diagonal interference/static with TG16 (no SSDS3)

[thebigcheese]

A while back I modified my TurboGrafx with an AV Driver so I could get RGB out. This is the procedure I followed (in fact, it is my video, so you can see my exact install in the video): https://www.youtube.com/watch?v=zagazNB5i9c. I didn't really notice the interference before with my PVM, but it's super noticeable with the OSSC, particularly on dark backgrounds. It is static that seems to be moving diagonally. Tried to get a picture, but it's kind of faint and hard to get a good shot of: https://photos.app.goo.gl/bCSN9CnDTb2jt8bt9. Anyway, it looks very similar to what people have been complaining about with the SSDS3 except that I don't have one of those and this happens with real games and with games off the Everdrive.

For those who don't want to watch the video, the TL;DR version is that the AV Driver is physically located just behind the expansion port at the back of the console. The wiring is all tapped from the pins of the expansion port. The output jack for the RGB is also on the back, so the wiring is all very short. The RF shielding for the console is still in place (though some of the pads were broken, so it's not connected quite as securely as it might once have been), the RF modulator was replaced with a new one from Console 5, though I will say it's also practically impossible to get a static-free picture with that (though I always assumed that was just because RF sucks). I also have GameTechUS's region mod installed, if that makes any difference (with the switch on the front of the console, again opting for fairly short wire runs). I'm also using the upgraded shielded cable from Retro Access.

Any ideas what I need to do to get rid of the interference? It's faint, but noticeable enough to be annoying

[BuckoA51]

What PSU are you using?

[thebigcheese]

I am using the Power+ one that HD Retrovision recommends. I don't have an original PSU, unfortunately, but I'm using this same model of PSU on my SNES, NES, and SMS and not getting noise like this on any of those.

Should also ask... When I got this thing, it was in very sad shape. Super dirty and beat up. I had to clean and reflow solder on the pins to even get it to read HuCards. I used a very temporary setup to get composite video out of the back just to make sure it worked because the picture out of the RF was horrible. As I mentioned, I replaced that and it got better, but still not great. Didn't think much of it since I wasn't going to use it anyway, but... yeah. At any rate, on the inside I didn't see anything that looked particularly bad, but might a recap help? The kit is pretty cheap and as annoying as it is to open this thing up, doesn't look like there are many to replace.

[thebigcheese]

Okay, I've now replaced all the electrolytics, but no change. None of them looked bad in the first place, but it was only $6 so why not. Anyone got any other ideas? I am stumped.

[FBX]

Just to see what happens, try disconnecting all audio lines from the board. See if the video still has the interference.

[thebigcheese]

Just to see what happens, try disconnecting all audio lines from the board. See if the video still has the interference.

No change In reading your comments on the SSDS3, I checked and digital and analog grounds are connected. I thought I'd try disconnecting the ground from the AV Driver just to see what happens, but I just got no signal at all.

[FBX]

Just to see what happens, try disconnecting all audio lines from the board. See if the video still has the interference.

No change In reading your comments on the SSDS3, I checked and digital and analog grounds are connected. I thought I'd try disconnecting the ground from the AV Driver just to see what happens, but I just got no signal at all.

Okay so the text step is to test proximity. Unfortunately you need good soldering skills, but the idea is to take the RGBS lines and hook them directly to the video processor pins. An example of this would be the RGB mod I did for my Super Grafx using The Great Voular's board:

[thebigcheese]

I have now done just that: https://photos.app.goo.gl/kiKCNDRYs9wvYWaz5. I moved the sync wire first with no change, then moved all the RGB lines, again with no change. I suppose I could try grabbing 5V from somewhere else or moving the ground. Do I need 5V connected to the output jack? I have it connected, but I don't know what things actually use that. I connect to a gscartsw_lite and then to a PVM and an OSSC.

Edit: disconnected 5v from the output and everything still works, so I think I will leave it off. No change, though. Also tried swapping to my original Genesis PSU, again no change.

[FBX]

I think you might also want to try physically relocating the actual mod board itself. It could be there's some interference depending on location perhaps?

If not, one final stab is to try using voultar's board.

[thebigcheese]

I had originally gotten one of those, but it doesn't boost the audio, so it doesn't actually work well with the TG16. I'm gonna try grabbing power off the 6260 instead, see if that's any cleaner. If not, then I guess I will have already moved most of the wires up top, so might as well move things around.

[FBX]

Yeah the NEC lines of consoles I'm finding out have a lot of weird issues with EMI. Yesterday when I was doing some tests with my Super Grafx and the mod with Voultar's board, I found there was a slight hint of diagonal interference when I ran the machine outside of its shell and grounding plate. When I put everything back together, the faint diagonal lines vanished completely.

[thebigcheese]

Alright, I think we are finally on to something. I relocated all the wires to the top so I could easily move the AV Driver around. Got some ugly long wires on it now. But! If I move it away from the console, the interference seems to change. I'm not sure why there was so much interference back there, but I will try relocating it behind the HuCard slot and see how that goes. Alternatively, I wonder if it would fit outside the normal RF shielding and if that might really insulate it from whatever is going on inside this console. Or I could build it a little metal shield of its own, but that might be bordering on OCD...

[FBX]

but that might be bordering on OCD...

There's no such extent when it comes to this hobby

[viletim]

Alright, I think we are finally on to something. I relocated all the wires to the top so I could easily move the AV Driver around. Got some ugly long wires on it now. But! If I move it away from the console, the interference seems to change. I'm not sure why there was so much interference back there, but I will try relocating it behind the HuCard slot and see how that goes. Alternatively, I wonder if it would fit outside the normal RF shielding and if that might really insulate it from whatever is going on inside this console. Or I could build it a little metal shield of its own, but that might be bordering on OCD...

Keep the video input wires and the AV Driver board away from digital stuff. A few mm off the board can make all the difference. Also try connecting the power close to the voltage regulator if you haven't already.

[thebigcheese]

I'll have to give that all a go. I moved the board and shortened the wires, pulling the pad off for the left audio out from the 6280 (I think?) in the process. Not the end of the world as it's not like I'm going to use the RF out any time soon, but this does mean I don't have left audio going to the ext port anymore. The real icing on the cake, though, is now it's gone vertical instead of diagonal. It's definitely more noticeable because of the angle I'm sitting at in relationship to the TV while testing but... I'm starting to really hate this console. What a poorly made hunk of junk. I am giving up for now before I break something else

[Kez]

Have you performed the jailbar fix? If you're getting vertical interference, that might help.

[thebigcheese]

Have you performed the jailbar fix? If you're getting vertical interference, that might help.

Yup.

Update: I added some more mounting tape below the AV Driver to raise it up some, then moved the 5v wire so that it's pulling power almost immediately after the regulator. Shortened up the wires, "fixed" the trace I broke, and put it all back together. By far my ugliest mod work: https://photos.app.goo.gl/UvawtsvK3isLABW87. It seems to be... better? On the title screen of Ninja Spirit, it's almost like part of the bottom of the black background is a dark grey instead. Don't notice it so much from a proper viewing angle and farther back on the couch, though. I think this is probably as good as it's going to get with this stupid console. Or at least, I don't know what else I could possibly do. I'm now grabbing all signal directly from the chips producing them and I've recapped it. I think it's just a gross, noisy console. Sigh.

Maybe I'll look into getting a PCE or CoreGrafx instead. Mods seem way more common for those :p

Edit edit: In messing around with my Everdrive, I'm not really seeing any interference now. Maybe the shielding in Ninja Spirit isn't as good? At any rate, if there's any left, it's basically negligible from the couch now. I'll have to go back and edit the install instructions I put on my wiki for this thing. Thanks for helping me troubleshoot guys!

[thebigcheese]

Or... it could be not any better. Seems to be mostly noticeable on black areas. Sigh. FBX, I've been following what you (and Voultar) are doing with the SSDS3 as it seems like the video problems you are seeing there are related. Maybe once you get some results there I will have some ideas. Wondering if switching to a digital ground or removing the RF modulator altogether might help. Though at this point I am thinking about switching to a CoreGrafx with an IFU as most of the mods out there seem to be a better fit for that kind of setup. Plus no RF modulator to bother with :p