SNES SCART cable - resistor on csync?

[leonk]

A couple of customers now complained to me that they get black screen on XRGB mini when using NESRGB with retro_console_accessories snes ntsc csync cables but they work perfectly fine with n64 and snes.

I got my hands on a couple of these cables and was shocked to find a 180 ohm resistor in the nintendo end!

Why the heck would anyone add a resistor to csync!?

[RGB32E]

Why the heck would anyone add a resistor to csync!?

Several reasons:

http://shmups.system11.org/viewtopic.ph ... c#p1153623

It is possible to adapt the TTL signal to the 75 ohm input with passive components. The method is different for each console. It should be thought of an a modification to the sync circuit of the console, not a stand alone circuit element.

The NTSC Super Nintendo TTL sync needs resistor of about 330 ohms installed in series at the console end.

Can't say why 180 ohm was used instead of 330 ohm, or why such a large sized resistor was used either without heat shrink tubing, but....

http://shmups.system11.org/viewtopic.ph ... c#p1177211

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.

While he's mentioning PAL Saturn pin 1, the same thing applies to pin 3 on SNES systems (PAL -> DC power, NTSC -> CSYNC). Unfortunately, there's no SNES RGB cable that works with all scenarios "correctly" (or optimally if you will).

[leonk]

Interesting.

Most of my customers want 1 cable for all their Nintendo consoles. But as Tim pointed out, there's no such thing. Probably the same thing applies to RGB modded early N64's, where the output is probably TTL CSYNC as well.

In the past, when someone complained, I would just change the "recommended" csync output type from 75 ohm to TTL, and the XRGB with this cable (with 180 ohm resistor) would start working correctly!

I wonder if this makes sense based on my reading: I don't think the XRGB cares too much on output impedance (much like a PVM, it will sync to those earlier 100 ohm PC Engine RGB amps). I believe the difference might be in the peak to peak voltage. It's simply higher in TTL, so the resistor attenuates it. With NESRGB set to 75 ohm CSYNC, the voltage is lower, and with the 180 ohm resistor .. it's too low for the XRGB (but not too low for a PVM I might add!)

[CkRtech]

I suppose you could always ask your customers the question "aaaaaand talk to me about the cables you want to use with this." Of course if they say, "I already have a SNES RGB cable," it is still an ominous response due to the questionable origins and "version."

"Why don't you go ahead and mail me that RGB cable along with your NES...." lol. That way, you could open it and/or test it before sending their NES back. They can just....use S-Video or composite while they wait.

[leonk]

I had a chance to look at the NESRGB CS# modification Tim did in V1.4+

- CS# on NESRGB by default is TTL
- To convert it to 75 ohm impedance, a 90 ohm resistor between CS# and GND is enabled by shorting J8

So, for those of you that want to use a single SCART cable with NESRGB, SNES and N64, setting the NESRGB to TTL (leave J8 open) and use the SCART cable with the resistor in the NES connector end is the best solution.

Personally, I have a cable for every console. My NESRGB cable has no resistors on pin 3, and J8 is shorted.

[mvsfan]

i dont get it. why would you only want 1 cable for all your consoles? ive got all my shit hooked up at once and a cable for each system and many switches.

[CkRtech]

i dont get it. why would you only want 1 cable for all your consoles?

<Erases long rant about the multiout>

Convenience.

[mvsfan]

how is it convienent to have to hook up a system every time you want to play it?

[leonk]

... and cost.

Not everone can dump $200 into SCART cables (after USD exchange rate, shipping and customs)

[CkRtech]

Well, it is basically a case for Nintendo users to jump back and forth between their consoles by unplugging the multiout from the back of one console and swapping it to another whenever they want to switch systems.

I don't do this, myself. I am just saying that I assume most users do it for convenience as well as cost saving measures (no switch, one cable). This would also mean their Nintendo consoles are all ready to rock with RGB.

[Thomas83lin]

Sorry for bumping\hijacking, but I was double checking my cables before a rgb install and noticed I have this exact snes cable with the 180 resist on csysnc. I'm fixing to be installing Tim Worthington's N64 RGB board v1.2 and was wondering if its preferred to use CS# or CS75 with this particular cable.

I'll be using this cable on a Snes and N64 mostly through a framemeister but I do own a pvm that I might use once in a while.
I'm hoping to not have to get another cable. Thanks in advance!

[pyroman512]

Sorry for bumping\hijacking, but I was double checking my cables before a rgb install and noticed I have this exact snes cable with the 180 resist on csysnc. I'm fixing to be installing Tim Worthington's N64 RGB board v1.2 and was wondering if its preferred to use CS# or CS75 with this particular cable.

I'll be using this cable on a Snes and N64 mostly through a framemeister but I do own a pvm that I might use once in a while.
I'm hoping to not have to get another cable. Thanks in advance!

I think you are asking the same questions I have been thinking lately. I would mod your cable to have 330ohm total resistance. All your consoles (n64, SNES, nes) should be set to TTL and then once they hit the framemeister they will be properly attenuated for 75ohm which it is expecting.

[ApolloBoy]

how is it convienent to have to hook up a system every time you want to play it?

I do this mostly because I don't have the room to have all my systems hooked up at once. Also it'd be a cable management nightmare.

[FBX]

I had a chance to look at the NESRGB CS# modification Tim did in V1.4+

- CS# on NESRGB by default is TTL
- To convert it to 75 ohm impedance, a 90 ohm resistor between CS# and GND is enabled by shorting J8

So, for those of you that want to use a single SCART cable with NESRGB, SNES and N64, setting the NESRGB to TTL (leave J8 open) and use the SCART cable with the resistor in the NES connector end is the best solution.

Personally, I have a cable for every console. My NESRGB cable has no resistors on pin 3, and J8 is shorted.

Older NESRGB boards don't have the jumper option and output TTL csync by default. As such, it's probably more consistent with other consoles to use TTL Csync and have the cable attenuate the lines. For example, my own NES has an older NESRGB board and uses a SNES multi A/V connector installed in the back. SNES RGB SCART Csync cables that attenuate the csync line work on it just as well as they do the SNES, so I simply order two of the SNES cables and one goes to the NESRGB NES while the other goes to the SNES.

[Thomas83lin]

Sorry for bumping\hijacking, but I was double checking my cables before a rgb install and noticed I have this exact snes cable with the 180 resist on csysnc. I'm fixing to be installing Tim Worthington's N64 RGB board v1.2 and was wondering if its preferred to use CS# or CS75 with this particular cable.

I'll be using this cable on a Snes and N64 mostly through a framemeister but I do own a pvm that I might use once in a while.
I'm hoping to not have to get another cable. Thanks in advance!

I think you are asking the same questions I have been thinking lately. I would mod your cable to have 330ohm total resistance. All your consoles (n64, SNES, nes) should be set to TTL and then once they hit the framemeister they will be properly attenuated for 75ohm which it is expecting.

Thanks for the reply, I've already checked around and have already modded my cable to 330 ohm resist on csync. I've asked Tim about using CS# TTL with my now modded 330ohm resist on csync snes cable, and he told me

"There is already a 330 ohm resistor in series with the CS# signal on the N64RGB board. It should still work with both resistors, but you might have better results if you place a shorting wire over the one on the N64RGB board. The series CS# resistor is R52."

So after talking to him, I plan on bypassing R52 on the N64RGB board and using my snes rgb cable with 330ohm resist on csync.

[myciviczc]

hello there

this is my first time here, so first of all thanks

I found this topic and need to ask about. I need CSYNC SNES scart cable diagram for cheap scart snes cable I got from ebay for USE with my RGB modded N64 with THS7314 amp.

the problem is the image is too bright, and is zoomed in, and cheker board image