RGB-connected consoles: fuzzy bars

Recently I was playing my RGB-modded SNES Jr. and I noticed some fuzzy bars moving down the screen. They appear only on blue objects. It's not incredibly noticeable, but it's definitely there. I've determined that it's not the cable I'm using, because I have the same problem with a different cable. I experienced this before with my Super Famicom, only it was much worse than this and seemed to be affected by audio. This does not seem to be affected by the audio, but I could be wrong about that.

Moreover, I've been looking at other consoles connected over RGB and I noticed it there too. On the other consoles it's barely noticeable - I probably wouldn't see it if I wasn't looking for it. But it's definitely there. Also, I can rule out a problem with my monitor because the issue does not occur with my PS2 connected over component.

So this leads me to one of two conclusions: either A) This is a common problem for several consoles connected over RGB, and the problem is slightly worse for some systems (such as the SNES Jr.) or B) The adapter I built to connect SCART cables to my Sony PVM is faulty in some way. I'm inclined to think A is the case because my adapter is very well built, and I've examined it closely many times and have never found anything wrong with it. I'm going to take a closer look at it in the future, but I rather doubt that there's anything wrong with it.

What are your thoughts?

 

I would look at the adapter you speak of. Analog signals of small amplitude are really sensitive to background noise. Maybe the Blue line of you adapter is not protected enough from such noise.

Also, maybe the blue line has a trace which contains too much copper(or any conductive metal used here) which would be resulting in a bad impedance matching. This could maybe creating an effect in which the wire is acting as a coil and therefore creates an energy retaining circuits that puts your blue line signal slightly out of phase. When the image gradually turn to black (bottom of the screen reached) and vsync kicks in, the virtual coil created will discharge and create those fuzzy bars.

You should post a picture of your adapter and maybe something will come out of this. I designed some analog systems and encoutered alot of issues that I ultimately fixed. I'm no pro at RGB signals since I live in North America and this thing is practically non-existent here but basic analog electronic concepts applies here.

Do you have a way to plug the console with RGB direcly to the TV without going through the adapter and the Sony PVM? Do you have a second TV that takes RGB without the use of your adapter?

 

la-li-lu-le-lo is in the same boat that I am in which is that all we have access to are Sony PVM displays for RGB. They have BNC connectors which necessitate SCART->BNC adaption. Though I've strongly considered installing a D-SUB25 connector wired in the same style as VGA onto my consoles so that I can use cables intended to take VGA from a computer and pop it into a projector. The cable I have modified was sold for that purpose however it has H-SYNC and V-SYNC as separate cables as opposed to standard RGB which simply has sync.

Wonder if what you're seeing is a hum bar? I noticed them on TG-16 hardware.

 

APE, this is similar to the problem I had before with the N64 when you initially sent it to me. That problem is gone now on the N64 (or nearly gone, anyway). It was also different - on the N64 it occurred on all colors, and on the SNES and other consoles it's only on blue.

 

have you tried clipping off the scart connector and soldering bnc connectors to the wires and see if maybe it is the converter

 

Interesting. I should be getting a new N64 SCART cable this week (or so I hope) and should be able to experiment a bit to see if I can reproduce this.

 

I opened up my adapter and took a look at the blue lead. It looked like it wasn't soldered very well - not so bad that I would expect problems like this, but I could do better - so I resoldered it. It made no noticeable difference to the image.

 

Well, for anyone who's interested, I found the solution a while ago (sort of). It appears that it is a problem with my adapter after all. I had suspected for a long time that there might be something wrong with it, but I wasn't sure until about a week ago. As far as I can tell, some of the pins on the SCART connector are loose or don't have good connections. I think the reason for this is that the soldering iron I used was too large, and thus in some cases the plastic connector or the pins themselves were slightly melted, causing them wiggle around when a cable is connected. A temporarily solution I found is to push the connector in the slot as far and as tightly as possible. When I do this, the fuzzy bars still appear, but they are almost invisible. In the long-term, I'm probably going to need to build a new adapter.

Any suggestions for what type of soldering iron to use for a project like this?

 

http://www.amazon.com/Weller-WLC100...e=UTF8&qid=1341646615&sr=8-1&keywords=wlc-100

This is what I used to do all the work on your hardware. I'm sure there is something out there that can offer more finesse but it has served me very well.

BTW, I found one of these at a thrift store last month for $2:
http://www.homecontrols.com/Automatic-TV-Sound-Regulator-CATVSR

I rewired the SCART connector and bought more male BNC->female RCA adapters and it works amazingly well. The cables used are also very well shielded and the female SCART connector is the best I've seen so far. Probably can find it for a better price somewhere. The only annoying bit is that there isn't a second red cable for stereo which isn't a big deal as the SCART cable I have for SNES/N64 use has a small block with composite and stereo plugs on it.