Sega Saturn - bleeding only in RGB ..

I'd go with a sync stripper as well, but installed in the upscaler itself.
Any CRT TV I've used works well with composite video for sync. I've never had stripes or sync dropouts.

But yea, installing the resistor instead of the EMI filter is viable.
The capacitor is necessary if the signal has a DC offset. It's optional if not.
AC coupling video signals is the accepted norm, so personally, I'd install it.

 

x

 

So that must mean that Tim Worthington used an oscilloscope to measure the signal levels...

I wonder if the same applies to PSX using C-sync raw.

http://assemblergames.com/l/threads/ps1-c-sync-help.56631/

If that is the case then we all have been using 75ohm resistors incorrectly.

I read somewhere that because Csync raw is TTL level signal, capacitors are not needed and are useless.
But I don't know if this is true!

I really don't know how to explain but I have always been under the impression that using Csync for sync would be better in terms of image quality.
I can testify that going from CVBS to Luma for sync on psx and Saturn resulted in clearer and crisper images for me.
And changing from Luma to Csync (raw) in psx made even more of a difference, especially during video playback in games. But suprisingly, not on the Saturn.

One other thing that I still don't understand is the Amiga 500 case.
It outputs Composite Sync TTL level and it is suggested to use a 330 ohm resistor.
But the official cable commodore sold to be used with 1084S monitor, for example, uses absolutely no resistor or capacitors, for that matter.
Could the monitor already been using those inside for precaution?
If so, wouldn't that mean that 1084S monitors are good (and perhaps safe) to work with Csync raw (digital, TTL level) signals from other sources...?

 

The 330ohm value is only because there is already a resistor in the amiga iirc. And that resistor (or in the amigas case both resistors) + the 75 ohm termination resistor create a voltage divider which reduces the signal level down to acceptable levels.

So the 330 ohm could be different depending on the console, so don't take that as a generic value.

 

Well, I decided to do the change on my saturn cable:



Pin 20 of scart has now a 470 ohm resistor (blue) instead of the combined 75ohm + 220uF capacitor.



(Forgot to say I have a model 2 Pal Saturn with Csync raw on pin 1 of the AV out socket.)

Picture looks ok, I think...

 

The plot thickens.. So the 3 failing Sega Saturn systems had one other thing in common, which I dismissed at the time .. they were all VA7. Just completed a BIOS mod on a VA6 and VA1, and they both had good CSYNC.

Hmmm....

 

I think this might be the problem I'm having but I'm not sure. Did any of those systems you fixed have 6-7 faint yellowish vertical bars that were easier to notice with dark colors on screen? Everything seems blurry too, especially around text.



I cranked up the RGB in PhotoShop on that first image so you can see better.

 

Hi guys,
here is my Saturn model no.2 PAL (I don't know PCB rev. yet) with RGB cable on LCD:

and on my PVM 20M2MDE:

My RGB:

Do I need to install 470 Ohm resistor like here:

?

 

PAL systems don't have the c-sync output, the same pin carries 12v instead.
Composite video or luma can be used as sync instead, your cable is likely wired for composite as sync.

no resistor needed there.

 

So what I need to do to have nice and clear picture on Pvm?

 

I tried these EMI filters suggested. Bought them from Mouser, but should be the same: http://www.mouser.dk/Search/Product...-RCvirtualkey65210000virtualkey652-EMI101T-RC

I don't think these are the correct value. With these in place the screen will darken rapidly when the disc drive is moving. It's especially easy to tell on a very bright screen.

The Saturn used is a model 2 "This is Cool", but I compared against another unmodified Jap model 2 where this was not an issue. I also tried two different cables, one original european Scart, and the other a 3rd party.

The "Cool" Saturn uses c.sync (swapped internally) and the unmodified uses composite video as sync.

Only other thing that I changed was adding the 470ohm resistor on the c.sync line, as suggested in this tread, but could this be causing it?

 

Hello. First let me apologize to bring back this old post but I'm having some problems with my Saturn's image.

I'm having this dark red colors on the left of the texts. The other colors in game are dark too.

https://imgur.com/a/5H9vq

Replaced the three caps associated to RGB pins and still the same.

My console is a PAL version.2 connected with the original RGB cable that have been tested and is working good. Tested with one of those scary to rca converters to force composite and the colors are darker too. And it happens with all the tv's I've tested.

Do you guys have any idea what is giving me this colour problems?

Thanks in advance.

 

Maybe bad capacitors