SNES Diagonal lines on my SNS-CPU-RGB-01 over S-VIDEO

[maton1200]

Hi,

I recently got a SNS-CPU-RGB-01 SNES. To my surprise, the video is not as good as with my old SNS-CPU-GPM-01 over S-VIDEO. There are some faint but noticeable diagonal lines. Please see the pictures for which I tried highlighting some diagonal lines:



I have only seen some workarounds for the APU board revision which imply lifting a PPU2 pin. I am not sure if that is going to work in my case since I am using S-VIDEO and lifting this pin seems to affect the composite output, not sure if the S-video output as well but I am not taking any chances until I am certain it won't affect.

I am using an official Nintendo AC adapter which has never given me any noise issues with my previous GPM-01 model and an S-video cable from amazon which I was also using on my GPM model without noticeable diagonal lines. This is one of the good ones that have the chroma and luma signals properly aligned instead of picking up the composite pins.

Any ideas?

Edit: This only happens with S-VIDEO and not Composite. Cannot confirm if it happens too with RGB since I do not have an RGB-capable TV or any RGB cables even.

[Josh128]

It more likely related to either your S-video cable, or any kind of switch or video selector you may be using than anything internally. Are the diagonal jailbars also present using a standard composite cable direct to your display?

[maton1200]

It more likely related to either your S-video cable, or any kind of switch or video selector you may be using than anything internally. Are the diagonal jailbars also present using a standard composite cable direct to your display?

How come I did not have this issue with the old GPM-01 model using this very same cable?

This cable is ok since it does not have the issue cheap models have of using the wrong component pinouts, it is pretty much a copypcat of the nintendo version and I use the same cable for my N64 without it causing noise issues. I do not think spending money on an official nintendo S-video cable is going to solve or mitigate the problem.

I do not see the diagonal crochet pattern using composite but I would prefer to keep using S-video . There has to be a workaround. I believe I saw somewhere some mention of a 470Ohm resistor on the Chroma line but it is unclear if this would help.

I have also noticed this SNES model also has some horizontal banding issues (some colors affecting other colors placed at the same vertical position but a different horizontal position). This affected my old model too but it is a bit more noticeable in this model. Here is an example of what I meant:



This could be a matter of replacing perhaps some capacitors, or the 7805 regulator itself but the diagonal lines are my top priority now. I was not expecting the RGB model to have a lower quality video than the GPM motherboard honestly.

[Josh128]

Well I would definitely try a different S-Video cable before doing anything internally. Even an el cheapo one.

[Syntax]

Diagonal lines are usually mains AC, try changing the internal regulator for a newer one or a different power brick.

[Josh128]

In my experience the tightly packed diagonal jailbars are more usually associated with the video signal path. Either cable issue or sync source (CV/luma/composite sync). I think its telling that he doesnt have the issue with composite video.

It can be related to the PSU but Ive never had any problems with original transformer style power supplies, only the cheap and light
solid state ones-- some of the 5V ones I've powered Neo Geo MVS units with could cause similar issues, but those issues were not the classic tightly packed ~45 degree angled lines.

Either way, good luck and report back what you find.

[NewSchoolBoxer]

I am using an official Nintendo AC adapter which has never given me any noise issues with my previous GPM-01 model

You should not be using that. The caps are long gone and causing the supply to output around 500mVpp ripple voltage and that is bad for the console's lifespan, especially the audio circuitry. Enough ripple voltage and current screw up everything. I like Syntax's idea to try a different power brick and replacing the internal regulator and the power line capacitors could help to a degree.

That Composite doesn't have the diagonal lines is interesting. Way I think think video works, is SNES digital RGB pulled from the game cart gets transcoded into S-Video and that gets luma trapped into Composite. It's possible the diagonal lines occur at frequencies that the luma trap filter removes for Composite and RF. Else Composite and RF are so blurry that the lines get meshed in. Worth cleaning the video lines and multiout pins with 99% isopropyl alcohol + q-tips.

The horizontal banding issue look like ghosting to me. Can see the outline of the log extend to the rest of the screen. Is a SNES thing. Neither of my stock SNES consoles have that problem, sometimes we're lucky. I disagree with the replace C11 strategy on that issue because it may or may not solve the problem and creates a new one. It's possible the better power supply / new regulator / caps can resolve it. An S-Video cable you know is 75 ohm would be nice and clean up the video a little but I've never seen that specified for retro gaming cables. Can DIY.

[maton1200]

I am using an official Nintendo AC adapter which has never given me any noise issues with my previous GPM-01 model

You should not be using that. The caps are long gone and causing the supply to output around 500mVpp ripple voltage and that is bad for the console's lifespan, especially the audio circuitry. Enough ripple voltage and current screw up everything. I like Syntax's idea to try a different power brick and replacing the internal regulator and the power line capacitors could help to a degree.

This issue did not happen with my older SNES model using the same power brick. Also, I believe the purpose of the internal regulation is to remove unwanted ripple as well as stabilizing voltage levels. I could always replace the old main capacitor of my power brick anyway.

I am using an official Nintendo AC adapter which has never given me any noise issues with my previous GPM-01 model

That Composite doesn't have the diagonal lines is interesting. Way I think think video works, is SNES digital RGB pulled from the game cart gets transcoded into S-Video and that gets luma trapped into Composite. It's possible the diagonal lines occur at frequencies that the luma trap filter removes for Composite and RF. Else Composite and RF are so blurry that the lines get meshed in. Worth cleaning the video lines and multiout pins with 99% isopropyl alcohol + q-tips.

I could try this.

I am using an official Nintendo AC adapter which has never given me any noise issues with my previous GPM-01 model

The horizontal banding issue look like ghosting to me. Can see the outline of the log extend to the rest of the screen. Is a SNES thing. Neither of my stock SNES consoles have that problem, sometimes we're lucky. I disagree with the replace C11 strategy on that issue because it may or may not solve the problem and creates a new one. It's possible the better power supply / new regulator / caps can resolve it. An S-Video cable you know is 75 ohm would be nice and clean up the video a little but I've never seen that specified for retro gaming cables. Can DIY.

Honestly, I think I gave up a bit on that. From what I read in other forums the RGB and APU models are quite prone to these "Diagonal lines" issues as well as other video issues. I am currently trying to repair my GPM model but it turned out to be more difficult than I imagined.