PAL SNES which scart RGB cable?

Started by PluueeR, March 13, 2014, 11:08:28 PM

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PluueeR

March 13, 2014, 11:08:28 PM Last Edit: March 13, 2014, 11:12:09 PM by PluueeR
A couple of weeks ago I bought a scart RGB cable for my PAL SNES from: retrogamingcables.co.uk. However I'm not satisfied with the result. The first problem is that it produces quite a  large amount of humm. This gets worse when the image gets brighter. This is probably due to bad shielding (or no shielding at all). The cables from consolegoods.co.uk are double shielded so they should reduce this problem.

Composite:



Scart RGB:


Is there a solution for this second issue? This problems occurs on both my Philips and Sharp LED TV's. I hope this can be solved in some way, because I really like the vibrant colors.

Andy-Antsinpants

March 14, 2014, 05:45:16 AM #1 Last Edit: March 14, 2014, 05:48:46 AM by Andy-Antsinpants
I had the same issue when using either an (expensive) RGB cable for PAL-SNES from Wolfsoft or modified a (cheap) Saitek RGB-cable for PAL-GameCube to work with my SNES. In both cases, the cables did only feature a common shielding, but no coaxial shielding amongst each video and audio signal line.

The result were faint video noise and humming sound on bright pictures, just as you've experienced.

I plan on ripping a cheap official Nintendo RGB-cable for PAL-Wii apart and will equip it with the SNES Multi AV plug. Let's see how this cable will do the job, since I expect it to have discrete shielding for every single signal line, judging from the sheer thickness of the cable.

unshe

It seems a "X pattern" issue.
use Luma (pin7) instead of Composite (pin 9) as source of sync, i think it will solve

Andy-Antsinpants

I didn't know about using the luminance signal as a sync source. I'll try it next time, thanks! :)

PluueeR

March 14, 2014, 08:14:26 PM #4 Last Edit: March 15, 2014, 02:29:42 AM by PluueeR
Quote from: unshe on March 14, 2014, 12:11:59 PM
It seems a "X pattern" issue.
use Luma (pin7) instead of Composite (pin 9) as source of sync, i think it will solve

I managed to crack the connector open and solder the wire from pin 7 to pin 9. And it solved the problem! Thanks for your input unshe! Now I only need to get rid of the humm.


unshe

To solve the "Humm" you have to carry more GND from snes to tv.

PluueeR

As test I bypassed the audio via a separate cable (standard RCA) . Less humm but still present. I then also connected the ground from the separate cable to the scart end (audio grnd) and the snes multi out grnd. Almost all humm is gone!

But when I connect it to my scart splitter most of the humm is back.

Both cables aren't shielded. Guess with a properly shielded cable the humm would be gone entirely.

imparanoic

try using real aluminium adhesive back tape ( proper one, not just silver coloured tape) on the entire cable, not expensive, and improves  shielding

unshe

shielding doesn't matter. It is a question of total GND quantity you use to connect Snes's GND and TV'sGND.
Using Shielded cable you will improve because you will connect both side at GNDs so you are increasing the size of copper bringing GND.

Fix_Metal

Quote from: unshe on March 18, 2014, 09:57:32 PM
shielding doesn't matter. It is a question of total GND quantity you use to connect Snes's GND and TV'sGND.
Using Shielded cable you will improve because you will connect both side at GNDs so you are increasing the size of copper bringing GND.
Beware of ground loops, literally  ;D
You should ground all the grounds with 1 wire and the common ground scart side. Nintento AV port comes with 2 grounds, which really do the job if they are both wired till scart side.
With one you wire the common, with the other you wire all the others. I usually wire them with rigid copper wire.
Take a look at this picture. I mean connecting all grounds together. That way, if your TV has a star ground point far from the scart connector, you will manually put to the SNES ground all the audio/video signals and get rid of hum.


PluueeR

My cable is finished (for) now. I'm really pleased with the result. Thanks unshe for the tips! Bummer that suppliers like consolegoods.co.uk and retrogamingcables.co.uk don't deliver this. I e-mailed both en they both replied about the sync to pin 7 that it should be on pin 9 and that was the end of it  :(.

I run the audio through a seperate RCA cable for which I connected the grounds together on both ends. Creating a small groundloop. However, there is less humm than with only one end connected. I'm happy!

beanieboy182

March 24, 2014, 02:20:27 AM #11 Last Edit: March 24, 2014, 02:35:02 AM by beanieboy182
hello!
can you show us how you connect pin 7 to pin 9 ???

i have tried just attaching a wire from pin 7 to pin 9 and it just makes the blues a little less blue ?
still i have quite the X pattern on the blue backgrounds and things?
help!
Also tried solding the wire (blue) from pin 7 directly to pin 9 (but think this is ground)
obviously that loses all blue in the image and still i have the X pattern
(im guessing this is all done on the scart side of things as thats what ive been altering)

PluueeR

I can't show you the inside of the connector, because I ve glued it together with hot melt because there was no strain relief.

You don't connect pin 7 to pin 9. You need to disconnect the wire on pin 9 and solder it to pin 7.

beanieboy182

we are talking about the scart pins or the snes pins ?
i think i got these 2 mixed up
i think i have to cut the trace to pin 9 inside the snes
and find the c sync and connect that to pin 9

is this correct ?

beanieboy182

Quote from: PluueeR on March 24, 2014, 06:56:50 AM
I can't show you the inside of the connector, because I ve glued it together with hot melt because there was no strain relief.

You don't connect pin 7 to pin 9. You need to disconnect the wire on pin 9 and solder it to pin 7.


i think im still confusing scart pins to snes pins lol

pin 9 (scart side) is connected to ground as of this diagram
http://members.optusnet.com.au/eviltim/gamescart/snespal.png

pin 9 (snes side) goes to pins 20 (scart side) and through a resistor 75ohm to ground pin 18 (scart side)
???

PluueeR

Quote from: beanieboy182 on March 24, 2014, 09:52:29 AM
we are talking about the scart pins or the snes pins ?
i think i got these 2 mixed up
i think i have to cut the trace to pin 9 inside the snes
and find the c sync and connect that to pin 9

is this correct ?

On the SNES multi out connector you need to disconnect the wire on pin 9 and solder it to pin 7.

Leave the SCART as it is.

beanieboy182

Quote from: PluueeR on March 24, 2014, 08:08:25 PM
Quote from: beanieboy182 on March 24, 2014, 09:52:29 AM
we are talking about the scart pins or the snes pins ?
i think i got these 2 mixed up
i think i have to cut the trace to pin 9 inside the snes
and find the c sync and connect that to pin 9

is this correct ?

On the SNES multi out connector you need to disconnect the wire on pin 9 and solder it to pin 7.

Leave the SCART as it is.

what is the easiest way of doing this ???
unsoldering pin 9 and pushing it back out the pin socket on the motherboard
or what ?

beanieboy182

Quote from: PluueeR on March 24, 2014, 08:08:25 PM
Quote from: beanieboy182 on March 24, 2014, 09:52:29 AM
we are talking about the scart pins or the snes pins ?
i think i got these 2 mixed up
i think i have to cut the trace to pin 9 inside the snes
and find the c sync and connect that to pin 9

is this correct ?

On the SNES multi out connector you need to disconnect the wire on pin 9 and solder it to pin 7.

Leave the SCART as it is.

ok i think i was being stupid
i just cracked open the end of the scart cable that goes into the snes (the multi out connector) and changed the pin from 9 to 7
hopefully this will fix it :D
just putting it back together now
dont do what i did and try to alter the actual snes (inside) multi out connector