RGB to YPbPr Transcoder Woes

[mesmer]

I recently bought this transcoder to connect my SNES and Saturn to my consumer (US) CRT that has YPbPr inputs. Unfortunately the quality is problematic. I already had cables that terminated in a VGA connector for a previous monitor, so I soldered up a vga-scart adapter. The SNES(ntsc) cable has 220uf caps on the rgb lines and is wired to use csync (I wired it myself). The Saturn cable I got custom from retro console accessories should be using csync, but I haven't verified with a multimeter.

Here are some videos:
cybernator
gradius 3
sengoku blade
radiant silvergun
cotton boomerang

- SNES looks decent. The main problem is the white is dull and yellowish, also there is some "banding"

- Saturn has sync problems. When the screen is all white, it looses vertical sync. Also, the lines move around horizontally as well, usually near the top, I assume this is a horizontal sync problem? There is much stronger "banding". Also on all white screens, the white gets quite dim and not uniform. I assume this is some sort of problem "clamping" the black level??

Has anyone used this transcoder before? Any success? I opened it up and there are plenty of pots to tweak, which is what I'll do next. Any ideas for other problems? Do I need to change anything with my console cables (resistors, caps)? Is the banding a problem with shielding on my vga-scart adapter I hand soldered?

Has anyone had good success with any transcoder? Which one? I've seen recommendations for Audio Authority and Kramer. I know there are the ones targeted for superguns as well (neobitz/jrok/etc.). I'm thinking of just going with a nicer one if it is a problem with the quality of this transcoder. Thanks!

[FinalBaton]

I have this exact transcoder and used it with all the consoles you speak of (except SNES) on a SD CRT with component inputs and it worked really well for all of them (although a Kramer unit will give even better results accordind to Fudoh).

Maybe your particular unit is defective?

[Xyga]

Tweaking the pots should do it. Never found a full list detailing those though, not to add the original and clone units don't share the same naming and disposition.

[FinalBaton]

Guy in this vid claimed the following
https://www.youtube.com/watch?v=yYN906grLsM

The controls are (by knob number):
1: Yellow/blue balance
3: Red/green balance
4:Red/yellow balance (very subtle)
6: Color intensity
NOTE: The above labels are just how I perceive what those knobs do. If your have proper technical terms or more info, I would be more than happy to correct them and credit you.

Don't know if accurate but it seemed to work close to that way when I tweaked the pots myself. He doesn't give his take on pots 2 and 5 though


WORD OF ADVICE : be VERY gentle when turning those pots, or else they will break on your ass
keep your screwdriver absolutely perpendicular to the board surface when screwing

[mesmer]

I have this exact transcoder and used it with all the consoles you speak of (except SNES) on a SD CRT with component inputs and it worked really well for all of them

Where did you get your SCART cables? Are they wired for Cvideo or Csync ?

I'm thinking that using csync is a problem, from here:

Like stated above both composite video or composite sync can be used on pin 20. Note: Composite video must be used as the sync input, not TTL level C Sync that most consoles output.

I'm not sure if the saturn and snes output 1v p-p csync or TTL level? I might need to get some regular scart cables with Cvideo on pin 20.

[FinalBaton]

Where did you get your SCART cables? Are they wired for Cvideo or Csync ?

I get all my SCART cables from retro_console_accessories on Ebay.
Some are Csync and some are Composite Video as Sync. They all seem to work ok in my setup *shrugs*

[mesmer]

Ah, some great info in this thread: http://shmups.system11.org/viewtopic.ph ... 3#p1153623

[antron]

I use this converter with NES SNES MD PS1 DC. I only have a problem when using c-sync (MD and NES), and then only with my wega Trinitron. Screen rolls with MD and tears with NES.

[FinalBaton]

So weird that you guys have problems with this onverter and I don't!
Maybe it's not exactly the same transcoder or something?

Mine was this one :
SPECIALTY-AV SCART to Component Video Converter for Sega, Genesis, Atari
by SPECIALTY-AV
http://www.amazon.com/SPECIALTY-AV-SCAR ... B004XSSDPO

looks like it's the same, IDK...



btw I've read on other forums that the power supply sent with this converter, by some sellers, is crappy and not up to task, creating ghosting and stuff. Could it be the problem?
Also, it'd be interesting to figure out what inside pots 2 and 5 do. Maybe one is related to sync or signal strength or something (but I'll admit that I'm not knowledgeable when it comes to current needed for feeding the sync pin etc)

[mvsfan]

I have that same converter and it works great. when i got it though the colors were off and i had to turn some pots.

but since then i havent had to open it up.

Your color problems and losing sync, sound like your running your consoles through a cheap scart switch.

I had a cheaply made one at first and i was having the same problems. sometimes the plugs would just fall out of it too.

[antron]

So weird that you guys have problems with this onverter and I don't!

For me it's TV dependent. Zero problems with a Samsung LCD!

[mvsfan]

I did have problems though, trying to capture component out of it though.

I was using a pexhdcap capture card and when i had the converter hooked up to it though component the colors would fade in an out and get a green tint to it.

Apparently its a known problem with that converter and the pexhdcap.

hooking the pexhdcap up directly to rgb through its dvi connector and bypassing any converter fixes the problem.

dont use component.

[bobrocks95]

That converter is a Chinese knock-off and I think the consensus is that pots shouldn't be necessary when converting to YPbPr, it's really just a set value.

"Buy something better" doesn't really help people who already have one though. Just as general advice eliminate any switches or anything else you have in your A/V chain to isolate the problem. From what I understood from what tim posted, cable manufacturers put extra components into the cable if it's a csync cable, so I don't think you can just switch the pins over and have it work. Do try other cables if you have them and try to determine if the transcoder just doesn't like csync (mine's fine with either).

If you do buy one in the future stick with an AA or Kramer converter. I also have a Keene one that works well and would appear to have spot-on colors.

[FinalBaton]

stick with an AA or Kramer converter

Speaking of that : what about the Kramer FC-4?
I haven't seen a single review on it... but since it's from Kramer it should at least be "very good". I wonder if it's just as good as the reference FC-14 though.

The FC-14 is rare as hen's teeth, but the FC-4 is still available new from some places

[bobrocks95]

The manual for the FC-14 lists a higher video bandwidth- maybe it can support higher resolutions than the FC-4? The Signal/Noise ratio is actually a bit better for the FC-4 so quality should be the same if not better, though I doubt it would be perceptible in any way on a CRT. Other than that connectors are of course different.

[mesmer]

So I messed with the sync and got some good results. Here is the saturn circuit I tried that tim said would make the csync the proper 1v p-p and ac-coupled as expected on scart pin 20. It got rid of all screen rolling on white flashes and all wavyness at the top of the screen and elsewhere. I also tried the 330ohm resistor for snes, and it looked about the same, but snes didn't have any sync problems to begin with.

Now it looks like my only problem is the color balance, and It sounds like that should be easily fixed by tweaking the pots. I guess I'll go ahead and buy some proper scart cables with Cvideo on 20. This one looks good, but It doesn't need to be so long, as I have a component cable on the other side of the transcoder.

[mesmer]

I took a peek at the board and visually traced the sync input, looks like it is about this:

Here are some snips from the datasheet

[Fudoh]

Speaking of that : what about the Kramer FC-4?
I haven't seen a single review on it... but since it's from Kramer it should at least be "very good". I wonder if it's just as good as the reference FC-14 though.

A few months back I talked to somebody who owns both and he's claiming that they got identical quality for 15 and 31khz signals. The FC-14 certainly supports HD signals as well, while the FC-4 wasn't built for that. I haven't tried the FC-4 myself though.

[FinalBaton]

Speaking of that : what about the Kramer FC-4?
I haven't seen a single review on it... but since it's from Kramer it should at least be "very good". I wonder if it's just as good as the reference FC-14 though.

A few months back I talked to somebody who owns both and he's claiming that they got identical quality for 15 and 31khz signals. The FC-14 certainly supports HD signals as well, while the FC-4 wasn't built for that. I haven't tried the FC-4 myself though.

That's awesome. the FC-4 can still be purchased new from £70, so that's a decently priced, top of the line transcoder option!

[bobrocks95]

That's awesome. the FC-4 can still be purchased new from £70, so that's a decently priced, top of the line transcoder option!

If you see this within the next hour or so, there's an FC-14 on the US ebay right now for $20...