Saturn RGB issue

[Koop]

Hay guys,

Quick note: This is being used on a bvm-20f1u

I have a model 2 american sega saturn. I picked up this cable:
https://www.retrogamingcables.co.uk/gam ... 3fb4c077bb

I selected the CSYNC Model 2 option for the cable.

However it appears I still have sync issues. Any ideas? Should I, for some reason, be using the model 1 cable for my console? It's somewhat confusing with the whole model 1 vs model 2 thing and all the motherboard revisions which is all I could gather from my googling on the matter.

[BuckoA51]

No such thing as a Model 1 cable I'm afraid. You might just need to try a different Saturn.

[Fudoh]

if csync is causing problems (possibly due to a higher TTL level) I would recommend using a cable which uses luma for sync. This works on all saturn units (PAL, NTSC, all models) and should provide the highest compatiblity along with the best quality.

[NightSprinter]

Fudoh: I have an NTSC Model 2 and actually measured the DC Voltage from the csync out. It's definitely a sort of "higher-than-usual" kind of out-of-spec. Model 2 csync is measuring at 2.75, which seems quite high to me. I've not had an issue with csync from a console unless it was above the 2.5V mark. For the OP and myself, can someone with a model 1 check the DC voltage of the csync line?

[BuckoA51]

No such thing as a Model 1 cable I'm afraid.

Just to contradict myself, seems Retrogamingcables is selling model1 cysnc and model2 cysnc cables, I'll e-mail him see what the difference is.

[Koop]

if csync is causing problems (possibly due to a higher TTL level) I would recommend using a cable which uses luma for sync. This works on all saturn units (PAL, NTSC, all models) and should provide the highest compatiblity along with the best quality.

I'm a total noob, I was always under the impression that csync was always the best- not true? And will I have any issues with using luma for sync on my BVM? Do I need to change any settings on my BVM itself to use that different sync or no? Thanks for the info.



I am a little frustrated with retrogamingcables guys... Been in contact with a 'Robert Fletcher' for 13 days now. They said they would send me a new cable which I thought was very cool of them- however for a while they were 'out of office' ... I thought ok no problem, I'll just follow up after they're back. Today I get this:



What is the deal with these guys? Is it just one dude? So now I need to wait about another week to get an update? Seems really unprofessional to me.

No such thing as a Model 1 cable I'm afraid.

Just to contradict myself, seems Retrogamingcables is selling model1 cysnc and model2 cysnc cables, I'll e-mail him see what the difference is.

From my understanding the difference between the model 1 cable on this site vs the model 2 cable is a 220uF capacitor.

Per Rob's email:
"The difference between the model 1 and model 2 rgb scart cable is that on the model 2 we add a capacitor and resistor onto the sync line, as these components where not added on the model 2 console from the video encoder. If you are having sync issues then we can send you an rgb scart cable without these additional components on the sync line which may resolve your sync issues."

But I don't get how removing the capacitor would help me if that's supposedly what I need for my model 2?


Hell I wouldn't care if the answer was to get a model 1. I'd love to just get the best picture quality for my Saturn games. I am just so confused on what model/revision I'd need to get to ensure it would work.

[leonk]

Koop: Can you describe what is your issue? what do you see on screen?

Also, when you connect via composite video.. does it look fine?

[Koop]

Koop: Can you describe what is your issue? what do you see on screen?

Also, when you connect via composite video.. does it look fine?

Uhhh...

So it had been a while since I tried it and now when I hooked everything it up it looks like it's working?

Before it was obviously something wrong with sync... Like you know, the picture was just going crazy.

Now it seems.. Fine? I dunno why. The menu looks normal but when I load up Nascar 98 you can notice there is a lot of 'stuttering' I guess you could say, like the whole picture is shaking a bit. Not sure if it's related.

I'm... not sure guys lol

[leonk]

I just finished modding a Saturn for a customer. It has the same issue I recently experienced on another Saturn. For some reason, there's a lot of color smearing, fading, etc in RGB.. but it looks great in composite video.

I traced out the entire circuit and discovered the issue. I was thinking you might have the same problem. But it seems to have gone away.

[Blair]

I have three model 2 Saturn's and one of them does this with my RGB cable, but the other 2 are fine.

[Koop]

Yeah I tried a bunch of other games and they looked fine to me, so I guess the issue is resolved.

Do you guys know if I could use this same cable on a model 1? I've heard model 1s have better output (possibly?).

Curious if you guys think a model 1 is worth the investment over a model 2, and if I could use the same cable with the cap in it.

[blizzz]

I don't have a model 1 to compare, but there are 0 issues with the video output on my model 2 Saturn (V•Saturn) using a retro_console_accessories cable. There are a couple screenshots on my page. But as I said, I see no obvious flaws, so I wouldn't recommend getting a model 1 over 2 or the other way around.

[leonk]

She has 2 different Saturn cables for sale. One is CSYNC, the other is Sync on Luma. According to her, some Saturn 2 models have CSYNC issues and hence why she sells the 2nd cable.

I only have the CSYNC cable. And the 1 console I recently repaired, the fault was traced down to an EMI filter gone bad. Changing CSYNC to Sync on Luma would have fixed the RGB SYNC issues on this Saturn, but would have not exposed the root cause of the failure. This is the 2nd Saturn (model 2) I found with this problem. If you are able to diag your PCB, maybe you can check your EMI filter. Use Saturn pinout online to figure out which EMI filter is CSYNC (On mine, it was 2nd in from the inside)

[Koop]

She has 2 different Saturn cables for sale. One is CSYNC, the other is Sync on Luma. According to her, some Saturn 2 models have CSYNC issues and hence why she sells the 2nd cable.

I only have the CSYNC cable. And the 1 console I recently repaired, the fault was traced down to an EMI filter gone bad. Changing CSYNC to Sync on Luma would have fixed the RGB SYNC issues on this Saturn, but would have not exposed the root cause of the failure. This is the 2nd Saturn (model 2) I found with this problem. If you are able to diag your PCB, maybe you can check your EMI filter. Use Saturn pinout online to figure out which EMI filter is CSYNC (On mine, it was 2nd in from the inside)

Yeah but if that was the problem could it not work one day and then work the next?

I'm gonna be honestly guys maybe I just like... Didn't have my sync connected to my BVM like a dummy ? I wouldn't put it past myself honestly.

[leonk]

An EMI filter is 2 coils with a 100uF cap to common ground. Sometimes the coils burn, sometimes the cap goes bad.

If it works now all the time, maybe you had bad connection at the time.

[BuckoA51]

I'm a total noob, I was always under the impression that csync was always the best- not true?

This came about mostly because of the XRGB3 which seems to really benefit from clean sync both on the quality of the picture (less checkerboarding) and because of the issue where the sync would drop out on particularly bright scenes if composite video for sync was used. Other scalers don't have these faults necessarily, so often clean sync makes no difference or Luma sync is just as good. Particularly if the consoles csync output is kinda off-spec it might be better to just use Luma than try and figure out what combination of capacitor/resistor or not you need. The new OSSC seems a bit less tolerant to off-spec CSYNC than the XRGBs were so this could become an issue in future too.

There are even a small number of consumer televisions I've encountered that won't work with clean sync/csync at all, though this is rare.

What is the deal with these guys? Is it just one dude? So now I need to wait about another week to get an update? Seems really unprofessional to me.

lol, you will find most retro shops are just "one dude" (or dudette, if you will, do people still say that?), it's not like there is such a big demand for this stuff that we can afford to hire staff

For the record, Rob disappears a LOT less often than the Retro Console Accessories lady.

[NightSprinter]

Not just the XRGB-3 and OSSC, but some monitors are similar in that aspect. For example as previously-mentioned: the NEC XM29 Plus (which requires pure csync without an Extron RGB 202PLUS, not sure how the Extron helps with that), the Model 2 Saturn and the "Boosted Sync" cables from Drew need the sync switch set to Hi-Z to be usable. Otherwise, all kinds of issues crept up (I have some examples in my Flickr gallery).

[leonk]

I think too much blame is put on the cables. If someone has access to good quality diagnostic tools, and don't mind taking Saturn apart and figuring out the issue, they'll discover the problem is not the cables.

For instance, I had 1 Saturn model 2 that was giving me issues in RGB on my PVM. If you trace the circuit on the main board, you'll discover that Saturn gets CSYNC directly from the 315-5687 GPU chip.

RGB and other outputs are generated by a CXA1645 chip just under the EMI filters (IC22) This IC does signal amplification, cleaning and outputs composite, S-Video and RGB. But not CSYNC! (That's why Sega decided to get CSYNC directly from the GPU)

All inputs into the Saturn 10 pin mini-DIN port go through a 100nF EMI filter. For some reason, the CSYNC one went bad. Most consoles don't have these or require them.

My point: switching cables would make this console work but the real issue (failing EMI filter) would still be there. The correct solution was to remove it and your standard CSYNC cables now work! It seems this is not an isolated problem. Maybe there's a design problem here that most people are not aware of.

[Edward_Tz]

Aren't the official cables using composite video for sync?

Why not use luma as sync like Fudoh suggested. Instead of modding the console.

[Koop]

lol, you will find most retro shops are just "one dude" (or dudette, if you will, do people still say that?), it's not like there is such a big demand for this stuff that we can afford to hire staff

For the record, Rob disappears a LOT less often than the Retro Console Accessories lady.

Yeah I've already noticed a trend with her unfortunately. Sent her a few messages and got no response. I'd really rather deal with people in the USA just for shipping purposes but if she never responds it might be a deal breaker I suppose. Well I don't want to sound like a whiny Walmart customer... Sorry!

As for Rob, he's been helpful just like, taking off every other week has been difficult to communicate with him, lol, didn't mean to make it sound like I was slammin' the guy but it is what it is. He did offer me a new cable which was really cool of him, so I have to give him props. Speaking of which I need to let him know everything is fine.

Either way, without them and forums like these I wouldn't even know about any of this stuff. So I owe you guys everything.

Thanks again to everyone who chimed in and discussed this with me. It's been really informative as I try and learn all this stuff.

[mvsfan]

There are so many different revisions of the model 2 i wouldnt be surprised if the problem is with a certain revision.

Model 1 -VA0 - VA2

Model 2 - VA2-VA15.

My model 2 works fine with a Csync cable. dont remember what revision it is though.

[leonk]

Aren't the official cables using composite video for sync?

Why not use luma as sync like Fudoh suggested. Instead of modding the console.

?? You should never need to mod a saturn to get sync. In my posts above, the system was BROKEN.. and I fixed it.

[Edward_Tz]

?? You should never need to mod a saturn to get sync. In my posts above, the system was BROKEN.. and I fixed it.

I misread then. I assumed you were talking about adding a capacitor to the csync line.

[BuckoA51]

?? You should never need to mod a saturn to get sync.

What about PAL systems? Can use Luma on those as an alternative of course.

[viletim]

The Saturn needs a 470 ohm resistor in series with the TTL sync output to make it compatible with a standard 75 ohm video input (SCART, XRGB, JP21, pretty much any monitor related to television). Otherwise the signal will be much to large and excessive current will flow from the sync output, through the cable, into the TV's video input. It causes unreliable operation of the TV's sync separator, buzzing in the audio, and possible damage to the c-sync output (leonk, your popped EMI filter was probably not a coincidence).

If that's not bad enough, if you unwittingly connect a PAL Sega Saturn, which has a 9V DC power supply in place of composite sync, you end up with it connected directly to your TV's video input. That will damage the TV, scaler, etc. It's no problem at all if there's a resistor in place to limit the current.

So don't forget to put the resistor in place. It's better it put it into the console end, as that reduces buzzing audio, but it will still do the job in the SCART end.

There are so many different revisions of the model 2 i wouldnt be surprised if the problem is with a certain revision.

Sega has the same TTL sync arrangement for the Master System, Mega Drive, and Saturn. Ie, connect the signal straight from the graphics chip to the AV port. After such consistency why would they turn around, make changes and break compatibility to some obscure part of the console that nobody used anyway (at the time)?

[BuckoA51]

I do notice a lot of audio buzz on the Saturn, I'll give the resistor a go then.

[leonk]

Hi Tim!

Is this the reason why your famous SCART cable page (http://members.optusnet.com.au/eviltim/ ... htm#saturn) shows SYNC on composite video rather than CSYNC?

Your information is very interesting. SCART cable manufacturers that sell CSYNC cables, don't use any resistors on the CSYNC line!

[cfx]

.

[leonk]

Another Sega Saturn model 2 came in for mod work today. Once again my CSYNC cable had all washed out image! (3 in 1 month!?) give me a break. I think there's a design flaw with these systems! Removed EM4 (TDK blue with 101 marking) and swapped with EM10 (Chroma). CSYNC problems went away!

This board is VA7.

[darcagn]

Hi Tim!

Is this the reason why your famous SCART cable page (http://members.optusnet.com.au/eviltim/ ... htm#saturn) shows SYNC on composite video rather than CSYNC?

Your information is very interesting. SCART cable manufacturers that sell CSYNC cables, don't use any resistors on the CSYNC line!

Syncing over composite video is the SCART standard.