Super Famicom interference patterns

Xan · Post by **Xan** » Mon Nov 24, 2014 2:33 pm

When running my SNS-CPU-RGB-02 console with a PAL GC RGB cable on a PVM, I get some patterns on solid colors like this: http://i.imgur.com/6UsRkX0.jpg

Would a Sync Strike help to get rid of this?

RGB32E · Post by **RGB32E** » Mon Nov 24, 2014 4:53 pm

Which cable are you using? Both the console revision and cable can be factors of seeing patterns in solid color fields. This is why the 1CHIP SNES systems are desirable as their RGB output is much cleaner than other SNES HW revisions.

Xan · Post by **Xan** » Mon Nov 24, 2014 6:49 pm

I just tested this on a consumer Trinitron, no visible interference: http://i.imgur.com/HKAOs1C.jpg

Perhaps there really is something to the statement that PVMs can't handle composite video as sync properly...

ApolloBoy · Post by **ApolloBoy** » Mon Nov 24, 2014 7:38 pm

Xan wrote: Perhaps there really is something to the statement that PVMs can't handle composite video as sync properly...

Some have issues with composite video as sync, but most PVMs will handle that just fine. All of the PVMs that I've used (1390, 1344Q and 1354Q) never had an issue using composite video for sync either.

Xan · Post by **Xan** » Sun Nov 30, 2014 1:14 am

It occured to me that it might be caused by the PSU, since I've had another case of a generic 9V switched mode PSU causing strong video interference. The aftermarket one I'm currently using is branded as being for the SNES, it's most likely switched mode as well. Hopefully an MD PSU will fix the issue.

Xan · Post by **Xan** » Sun Nov 30, 2014 8:53 pm

I tried a linear Roland adapter and comparing it with the aftermarket PSU, it gives same result. I've also excluded the Super Everdrive as a possible cause, as my SGB2 gives the same grainyness in darker tones.

At a bit of a loss right now... I find it hard to believe that the RGB output from the SNES/SFC is really that subpar. Guess I could always use my ill-calibrated consumer set where I don't see the issue?!

Looking at these comparisons I can maybe see a hint of grainyness, as much as the JPEG compression allows anyway...

kel · Post by **kel** » Mon Dec 01, 2014 3:14 pm

Have you tried a proper NTSC SNES Scart cable yet?

You may get away with PAL GC Scart cable with the NTSC SNES on some displays but it's not ideal. There is an extra cap and resistor on the C-Video line in the PAL GC Scart that isn't needed with the NTSC SNES. Both or either of these could be the cause.

Xan · Post by **Xan** » Mon Dec 01, 2014 3:29 pm

No, I don't own a NTSC RGB cable. Good point about the resistor and cap, I'll look into picking up one of these cables.

julencin2000 · Post by **julencin2000** » Tue Dec 02, 2014 11:58 am

Get a good old fashioned brick power adapter and a good shielded RGB cable. These two things make a big difference.

Xan · Post by **Xan** » Thu Dec 04, 2014 11:27 pm

Searching the forum for something completely unrelated, I found this post: http://shmups.system11.org/viewtopic.ph ... cb#p913301

First picture looks exactly what I get on my PVM.

BuckoA51 · Post by **BuckoA51** » Fri Dec 05, 2014 12:18 am

It's a common problem with PAL SNES, especially when running 60hz on a 50hz console. You could try a luma for sync cable. I should have a review of one in the next week or two.

Edit - Just re-read and you're using a NTSC console with a PAL GC cable? In that case, switching to a clean sync cable should cure the problem.

Xan · Post by **Xan** » Thu Dec 18, 2014 11:20 am

I just got a very cheap and yellowed SHVC-CPU-01 console from Japan, and lo and behold, those interference patterns are completely gone now. Same monitor, same cable: http://i.imgur.com/8QZcDPr.jpg (I don't know if the crappy photo represents this, but just take my word for it)

Based on this, the RGB-02 (and similar revisions as well probably) are to be avoided like the plague... the CPU-01 is noticeably sharper too. There's even more to it, though; the dreaded vertical line is not visible on my console AT ALL. This is something that not even the 1-CHIPs can provide IIRC, hence why people mod SFC Jr.'s. But considering the superior game compatibility of the 2-PPU setup and slightly better audio, I'd rather say the CPU-01 is the console to get. There's just the question whether all consoles with this model number are the same in regard to the vertical line.

Fudoh · Post by **Fudoh** » Thu Dec 18, 2014 11:23 am

Based on this, the RGB-02 (and similar revisions as well probably) are to be avoided like the plague

yepp, I can agree on that. Had one some time ago and was shocked about how bad the video quality was.

And yes, no vertical bar problem on the early SFC models. That's quite known though.

Xan · Post by **Xan** » Thu Dec 18, 2014 11:34 am

Why are people raving so much about the 1-CHIPs then? The small gain in sharpness doesn't vindicate the presence of the vertical bar, frankly.

I was partly hinting at the NA consoles with my last sentence; SHVC-CPU-01 boards were present there as well, I believe. Does this depend on the S-ENC chip or something?

Ed Oscuro · Post by **Ed Oscuro** » Thu Dec 18, 2014 11:44 am

Xan wrote:I was partly hinting at the NA consoles with my last sentence; SHVC-CPU-01 boards were present there as well, I believe.

Unfortunately I can't test it since it appears dead, but I'm pretty sure this was the board revision of the SNES I opened a while back, so yes.

Fudoh · Post by **Fudoh** » Thu Dec 18, 2014 11:52 am

Why are people raving so much about the 1-CHIPs then? The small gain in sharpness doesn't vindicate the presence of the vertical bar, frankly.

I still think it's quite a difference. The 1CHIP units just have perfect sharpness, while the 1st Gen units have a soft right edge, especially to dark colors (e.g. black vertical bars show a slight shadow). On a CRT that's perfectly fine, but if you have a XRGB with a big screen LCD, it makes a difference.

I would say 1CHIP (-03 or with vertical bar fix) > 1st Gen units > anything else.

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