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View Full Version : Turbografx amp / scart wiring question.



Billkwando
07-06-2013, 11:14 PM
I've gone rgb crazy, and I wanted to build a scart cable for my tg16 to use w/ my YUV box. I'm using the mmmonkey amp tutorial (3 transistors) and the expansion port to tap the signals, and I wanted to know a couple things.

1. What's the 75ohm resistor about with scart? Do I need it/them? I already ordered a bunch, but I wanted to be sure.

2. If the 75ohm resistor is required, and I build my amp inside a female scart connecter (just like the plug housings everybody uses but female) will any male to male scart cable have the resistor (or is it more than 1?) or would I add it to the female socket where the amp will be?

Thanks!

Yodd
07-06-2013, 11:34 PM
It's not necessary since you won't be using this with a Euro Scart TV.

The resistor goes between Pins 8 and 16. Normally 5 volts is sent to pin 8 and via the resistor to pin 16. Pin 16 will have a lesser voltage due to the voltage drop across the resistor. Maybe a volt or so. This is used for Euro TV's to detect if the incoming signal is composite or RGB.


Since you won't be plugging this into a Euro TV, you don't need it.


I would still run 5 volts to pin 8 (though not needed in this instance). But don't worry about adding the resistor between pins 8 and 16.

Billkwando
07-06-2013, 11:42 PM
It's no necessary since you won't be using this with a Euro Scart TV.

The resistor goes between Pins 8 and 16. Normally 5 volts is sent to pin 8 and via the resistor to pin 16. Pin 16 will have a lesser voltage due to the voltage drop across the resistor. Maybe a volt or so. This is used for Euro TV's to detect if the incoming signal is composite or RGB.


Since you won't be plugging this into a Euro TV, you don't need it.


I would still run 5 volts to pin 8 (though not needed in this instance). But don't worry about adding the resistor between pins 8 and 16.

Thanks for the fast answer! :D That's exactly what I needed to know. Just out of curiosity, do you know if male to male cables have them? I guess not, since it sounds like that would prevent it from working with composite video.

Oh and what's the pin 8/5v thing about (as in why would you still connect them)? I could probably look it up but I think you would explain it more understandably. ;)

Yodd
07-07-2013, 12:16 AM
Thanks for the fast answer! :D That's exactly what I needed to know. Just out of curiosity, do you know if male to male cables have them? I guess not, since it sounds like that would prevent it from working with composite video.

Oh and what's the pin 8/5v thing about (as in why would you still connect them)? I could probably look it up but I think you would explain it more understandably. ;)


Male Scart cables do not have resistors in them.


5v to pin 8 is traditionally used on Euro TV's to indicated aspect ration (i.e 4x3 or 16x9). While that is of no use to the component video encoder, it's nice to have 5v ran down the scart lead in case you want to power something like a sync stripper circuit or other circuit.

Like I mentioned, you totally don't need it wired. It's just a forward thinking convenience.


However, in the first post you mentioned using a female instead of male connector.

Any reason why?

Or are you integrating the female connector directly onto the TG16?

Reason I ask, is because if you plan to plug in a Male scart cable in from this female connecter on the TG16 to the female connector on the component encoder, you want to make sure sync and audio are on the right pins. It's different when you use a Female scart connector as an output.

Billkwando
07-07-2013, 01:13 AM
However, in the first post you mentioned using a female instead of male connector.

Any reason why?

Or are you integrating the female connector directly onto the TG16?


Yeppers! I was hoping that the pin numbers would correspond to their male counterparts. My idea was to run a short lead from the expansion port pin connectors out the little cord hole where the skinny power cable comes out. I believe there would be room for both to comfortably fit....I think. lol

A short female connector seemed tidier than just having a long cable semi-permanently attached to the console. Obviously a din jack would be more elegant, but I'm thinking of a mod that requires no actual modding (other than maybe a little cutting inside the snap on back cover where you can't see, if one was absolutely insistent on using it (my idea was to use a tight zip tie on the cable, just inside the hole, as stress relief. I also thought of a breakaway cable design, like the xbox controllers use, but really how likely is someone to trip over their TG16?

Yodd
07-07-2013, 01:49 AM
if you are going to use a female jack, wire sync to pin 19 and Right audio to pin 1 and left audio to pin 3. Otherwise when you use a male to male scart cable, you won't get audio or sync/picture will be scrambled/rolling.


I personally would install a 8 pin mini din connector where the original RF jack was. It fits perfect and doesn't require you to enlarge the hole at all.


Here are some pics of a TG16 I did last year:

https://lh4.googleusercontent.com/-6VPnQFnOdO8/UHEODT1Na6I/AAAAAAAAB1s/I_q0RUV88Ts/s1028/IMG_0757%2520%2528Medium%2529.JPG

https://lh4.googleusercontent.com/-NSwfpHRcyx4/UHEODUUFTAI/AAAAAAAAB10/kbXZSiduGW4/s1028/IMG_0758%2520%2528Medium%2529.JPG

https://lh3.googleusercontent.com/-9IEjluPPgRM/UHEODVOQxII/AAAAAAAAB1w/EMfkFoKD3Q0/s1028/IMG_0759%2520%2528Medium%2529.JPG



Looks almost completely stock.

You can also see my internal RGB amp. Unless have some specific reason, I would install the amp inside the machine.

Billkwando
07-07-2013, 02:12 AM
That is awesome, but I'm not that good at soldering. I bought a bag of transistors to do this mod:

http://www.mmmonkey.co.uk/pc-engine-rgb-amp/

and figured I could do the exact same thing that he did in a scart plug, but in a scart jack. That way, it could be completely self contained and wouldn't require opening the console at all. I just thought it might be a cool doodad for people who want to keep their machine stock for whatever reason, or if they're poorly at soldering and don't want to risk wrecking their system (me, lol). It's kinda ironic cos I bought a gamebit and then found out that my N64 is too new to be modded, and then I found out about the expansion port version of the TG-16 mod. No screwing for me.

Funnily enough, my iScan Pro is on the way, and it has a brightness and contrast control, so I might not really need an amp at all, assuming what I've heard (no amp = darker picture) is true.

billbrasky
12-09-2014, 04:35 PM
hey billkwando, i recently did a quick expansion port rgb deal and found this thread when trying to verify the 75ohm resistor on the scart cable. anyway if you're still thinking of going the plug and play route here's the one i did, using broken's rgb amp and the same pinout to the 8-pin mini din from your post. i've done both the internal mod broken mentioned and this expansion port method and i do sort of like the add-on approach better (if you can find a nice enclosure). but of course this is only possible with the PCEs with expansion ports.

http://i.imgur.com/qbkQC0L.jpg
http://i.imgur.com/Ia9dHBQ.jpg
http://i.imgur.com/jxNrLq9.jpg
http://i.imgur.com/7UhJB33.jpg

Atro
12-09-2014, 05:09 PM
Broken, I'm not sure what's underneath your amp on that TG16, but just for the record, PAL TG16's don't need an RGB amp for the mod.
They have a SONY CXA1145 encoder, so the signals can be directly tapped from there.

A friend of mine did it, but it sucks anyway as he can't find any 60Hz mod for the beast.

Billkwando
12-09-2014, 08:26 PM
Hey! Thanks for thinking of me. I still have all the parts and got sidetracked working on other projects (https://www.youtube.com/watch?v=cWsnDW66YZ8&list=PLa2pARIPC9cNxTJnWsDsoCNRAsI_CBA11) but I was just looking at my SCART connectors the other day, thinking I need to finish.