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4 поколение / RGB на чипе TCT-6801

« : 20 Апрель 2023, 22:56:11 »

The traces were cut a couple milimeters away from the chip, so there is nothing else but my circuit .. I went for a rebuild and changed the transistor and the capacitor and tested, but still nothing on screen. So I called it a day and restored the traces back to composite video. One of the traces broke but I was able to jump wire it to where it belongs  . Now the clone is back wherenI started. I think I will leave it to rest, still no colour in the 60hz ntsc setting.
I will attempt this modification on a tct clone when I get one of those 
This is just the beggining, I will eventually get it to work. Thanks for the diagrams and the pictures and your good will to help me guys.

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4 поколение / RGB на чипе TCT-6801

« : 20 Апрель 2023, 18:42:38 »

Hello brother, greetings, The wiring is almost as the diagrams, except for the traces and distance between each component, I paired the components closely and the signals directly to those joints, Maybe thats the issue, I consider rebuilding the entire thing and leaving the space, maybe its all clustered up and because of that it doesn't work.
1- the transistor I used says C945 and other words and numbers, I don't know if it makes a difference but I was suspecting of it too. I will replace it just in case.
2- power and ground is ok I believe, the transistor runs at 5v fine and there is no overheating, on the other legs appart from vcc it outputs 4volts or a bit less. if its NPN analog I really can't say nor how to determine it.
3- I will also replace the resistor for one of at least 3k next time.

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4 поколение / RGB на чипе TCT-6801

« : 19 Апрель 2023, 00:45:33 »

Hello. It took me 4 hours maybe, but I built the thingy and made the soldering to the pins, cutting traces and all. I checked and double checked everything carefully before testing. But I get nothing on screen 
I had to pair 150ohms resistors in order to get 75ohms in the outs. And the 3.3k resistor is abscent, I only got a 2k instead, but as it is going to the 5v I thought it wouldn't be an issue. Maybe it is, the transistor is recycled from an old vcr but i gues it works as it the one the diagram requires. Just in case I swapped the cables in case C and Y were crossed, but still nothing happened. I don't know where the deal is. Or maybe its just not meant to work.   

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4 поколение / RGB на чипе TCT-6801

« : 18 Апрель 2023, 00:17:56 »

Yes I understand, I put some heat on those pins but still. So you are used to play always in Pal setting, but with 60hz its still the same. in the board there are 3 solder dots as jumpers, but they arent connected, one of the dot has 5v, the other is ground I guess and the last one is going to the smb... I will keep checking what is the deal with this haunted clone of mine 
Once I install the s-video mod, it WILL have colour in every setting right? Because I will be getting the signals right from the chip bypassing any dead component there might be on the board . Right?
 if you have any other suggestions please let me know.

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4 поколение / RGB на чипе TCT-6801

« : 17 Апрель 2023, 20:17:42 »

Very important information indeed. Thank you again.
Last night I was messing with the switches in my clone, there are 3 switches.
The first has 4 positions (ntsc 60hz- pal 50hz -ntsc and pal again)
The second also 4 positions (I think for regions)
And the third switch only has 1 and 2 positions. In the first position the sega is turned off and in the second is on...

The thing is I tried to measure the pins of that third switch to the ground of a capacitor and somehow I made a short or whatever, but the colour in the ntsc 60hz returned! Weird stuff.

It only worked until I turned the console off an on again and ntsc60hz went back to black and white... 

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4 поколение / RGB на чипе TCT-6801

« : 17 Апрель 2023, 00:53:58 »

Thank you all for your responses, yes I will double check everything before I power it up, I see there is already a transistor on the board. As I have to completely cut that part of the genesis I guess I might take it and use it in the new home-made thing. One less component to find ...
Please confirm if the image I just made is correct?

EDIT: Sorry the 52 is Chroma and the 53 is Luma. I pointed them reversed.

EDIT2: According to the sm801 pinout pdf document I pointed correctly but in the diagram the C and the Y are reversed in pin number.

Hopefully the s-video diagram is only number mistaken and not pin mistaken.

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4 поколение / RGB на чипе TCT-6801

« : 16 Апрель 2023, 23:32:26 »

Thank you, thank you for real Russian brother . Yes, Id better not lift the pins, might as well do as your experience say. I will start searching for the components right away, I have novice- intermediate soldering skills, but that was enough to pull out a couple jobs like in the image, that simple circuit for s-video for the clone and original genesis/megadrive is all over internet and is really easy to build, plus makes miracles.
Again thank you whenever I have the circuit built and tried I might post the results.
I have another question. That 5v input is for running the image in ntsc 60hz right?

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4 поколение / RGB на чипе TCT-6801

« : 16 Апрель 2023, 22:45:33 »

Ok , you are definitely showing me what I want to see and read,
You say I lift the pins from the chroma and luma outs of the sm801, then I should build that set of resistors and caps and make the pins signal go trhough that set you built and out to a s-video chassis? If thats what you made in your machine I guess it would work just the same in mine because goacs are the same in each model. I dont care for composite nor switches. Just S-video output and I will never use composite again  please if you are allowed to share the values of those components in your picture and its circuit scheme, even hand-drawn I will understand and start searching for them so I mighr build it and experiment.

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4 поколение / RGB на чипе TCT-6801

« : 16 Апрель 2023, 20:35:15 »

Thank you so much for your reply, I might check those pins later on in order to try gettin the ntsc colour back, maybe it is a smd capacitor gone off? Maybe the crystal... Ill check when I have time.

Im most interested in getting s-video from these clones, one guy uploaded some pictures but I still dont understand how he installed those inside, but its becoming really clear everytime you guys show information about this. I tell you, its unique, I never thought S-Video would be possible in model3 clones, I don't take RGB too serious because where I live there aren't RGB/Scart Tvs available, we need an expensive RGB to Component converter to be able to enjoy such quality, so S-video is the cheapest DIY option. I would really love if anyone of you guys make a video installing one of those circuitry inside the clone and adapting the female chassis connector to the body of the sega. I have made several S-video installs on model 1 and 2 clones so the only clone missing in my curriculum is the model 3     .Sorry for the lenghty message because I don't want to infringe multi post policies. Again thank you for you forum, its great if I ever get S-video from my genesis will be thanks to you boys.

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4 поколение / RGB на чипе TCT-6801

« : 14 Апрель 2023, 19:20:56 »

This is the clone Im trying to learn to get s video from. It has a black and white ntsc image right now because I messed it up, but still I might attempt to mod it for s video, just for knowing the procedure and perform it in a future with another full working console.Greetings from Argentina. 

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4 поколение / RGB на чипе TCT-6801

« : 14 Апрель 2023, 18:29:32 »

(Ссылка на вложение)

Entonces debo levantar los pines chroma out y luma out del SM801 y luego intentar replicar ese circuito? Alguien ya lo hizo y tiene alguna imagen del interior de la consola con el trabajo hecho?

Добавлено позже:

Hello. I used this scheme and made my own pcb in eaglecad. Then made order on jlcpcb.com and got quite good result. It really works fine.

I have an issue, my clone model 3 with sm801 had a short in a rca mod I made and the colours in the ntsc setting went off, now its a black and white image, but in pal it looks fine, colours and all. What could it be?

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4 поколение / RGB на чипе TCT-6801

« : 24 Октябрь 2022, 07:21:41 »

Dido, на tct-6703, 6801, 6803:
120 - Y (люма)
121 - C (хрома)
Схема:

Please. Would you share an image of the job done to get s-video? I am terrible at reading schematics and can't tell if you cut traces or what. Please I am very interested, greetings from Argentina, we have tons of genesis clones here    hope you or anyone could help me.