RGB на чипе TCT-6801

[demolition.nick]

Dido, я выаодил s-video с клона на tct6001h, там всё аналогично. Покупать всякие ths кроме как для rgb не вижу смысла. Схема видео во всех современных клонах одинаковая, я просто взял стандартную схему видео, далее нашёл все соответствия на плате, пронумеровал всё на схеме так как это пронумеровано на плате (это всё тупо для дальнейшего удобства).
А дальше по схеме тупо выпаял несколько деталей и подпаялся куда надо. По выходу хромы резистор вроде на 75 ом и кондёр вроде 100нФ (не помню уже).
Остальные номиналы возможно менять не придётся.
У меня svideo вход только на тюнере в компе, но разница ощутимая. Почти как RGB
Короче делай по картинке, не забивай голову

[coconut76]

demolition.nick, а можно в личку схему вывода Svideo на таком чипе ??? Пожалуйста

[demolition.nick]

coconut76, чё сразу в личку. Если речь о TCT6001H, то 4 - люма, 5 - хрома. Схема та же. Всё стандартно

[coconut76]

  спасибо !!!!

[Фамиклон]

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

Вопрос по схеме: нагрузочные R44, R45 встречаются на 500 Ом и 1 килоОм, плюс на выходе сопротивление 10-100 Ом - имеют принципиальное значение?

[Cristián Molina]

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.

[Penyek]

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.

[Rumata]

It really works fine.

А почему бы ему не работать? Только схема вызывает некоторые сомнения. Входы вообще можно было оставить как есть. Просто не монтировать второй выход.

[Rumata]

[Cristián Molina]

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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?

[Cristián Molina]

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. 

[Sanyameloman]

Hola, amigo!
Did you check VCO_sel (xdiv), TV N/P, and TV 6/5 pins (pin 46, pin 3 and pin 4 correspondingly) on your chip? There should be some kind of jumpers/switches (sw1, sw2, etc.) coming from these pins of SM801. Please look at the topic attached to find proper jumper configuration for your clone:
https://www.emu-land.net/forum/index.php/topic,79285.0.html
Black and white NTSC image might be a result of jumper mismatch.
UPD: This chip also has RGB and C-sync out, thus RGB mod is possible but you'll need to work hard to install it in that tiny case
There are some schemes of S-video mods available in the web. Please find attached pictures:
I've done the second one (Another S-video scheme) on the clone with TCT6001H chip but the image was dark and the composite video quality was also lost. It feels like you need to switch chroma and luma signals between composite/s-video circuits to make them work properly. When I've switched off s-video mod the composite signal returned to a normal state.

[Cristián Molina]

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.

[Sanyameloman]

If you say that you've made some modifications with composite video amplifier - may be it would be better to check them again)
I don't think that you have problems with the chip if in the PAL mode the picture is OK.
As far as I can see you have 2 quartz resonators on your plate. Is it a "default" set or you've installed the second one?
Maybe you'll need to check k1, k2, k3 switch pads closely.

And what about S-video... I know that some people disassemble the composite video output in order to make an S-video one. Is it an option for you?)

Upd: In my MD2 clone everything is simple - take a breadboard and do whatever you want (see the creepy image below ))
On the picture below you can see the scale of my mod: left pin is luma (Y) the middle one is GND and the right one is chroma (C).
I've never seen a genesis 3 clone but, IMHO, the roadmap of the process would be the following:
1) make a mod on separate plate/breadboard piece;
2) cut chroma and luma tracks from pins 52 and 53 to insert 2 switches similar to O/J or N/P in order to switch between s-video mod and composite video and place them in available place e.g. in the bottom holes;
3) connect the output s-video signal to md2 av female connector (and make the custom cable) or provide a separate case-attached s-video female connector (the second picture).

[Cristián Molina]

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.

[Sanyameloman]

Dude, I DO NOT recommend you to lift the chip pins - as for me it would be safer to cut the tracks to composite video amp and tap to the track remains near the chip) I've already broke one pin on my SM801 chip while doing an RGB-mod)
For the scheme on the photo above you'll need:
2 resistors of 1 kiloOhm (1k);
2 resistors of 75 Ohms;
1 resistor of 560 Ohms;
1 resistor of 3.3 kiloOhms (3.3k);
1 condensator of 0.1 microfarade (0.1 uf);
1 transistor c945.

All the details placed in a row exactly as on the scheme that I've already mentioned above.

May the force be with you and, as a DIY desperado, remember: you do this at your own risk

[Nhisti]

Sanyameloman,

"Force" из ЗВ с заглавной пишется   

[Sanyameloman]

Nhisti, ну да, простите падавана)

А если по-серьёзному для "одарённых", то бишь для меня: есть вариант, как одним переключателем (желательно ползунковым, как регионы переключают) коммутировать сразу две дорожки?
Подскажите, пожалуйста.

[Cristián Molina]

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?

[Sanyameloman]

I have really bad theoretical skills in electronics but it seems to me (if I got the question right and we're still talking about s-video mod scheme) that 5 volts it's just the power for transistor and it's doesn't depend on NTSC/PAL specifics. You just power the transistor and it amplifies the signal - that's my lamer's logic)))
P.S. By the way, do not mess the position of transistor in a hurry or something like that - on the photo it looks with a flat surface to the left. But checking the real pinout of collector, base and emitter of transistor you'll find with the graphical description on the scheme would be much better. Just in case, you know

[Cristián Molina]

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.

[Sanyameloman]

I quote you a translated comment of one cool russian guy about the initial SM801 scheme:
One IMPORTANT point! On a couple of available SM801 circuits, for some reason the C and Y signals from the processor are mixed up. It is very easy to determine where which is on other processors. The brightness signal (Y) passes through the 22uf electrolyte and through the 100µH inductor, and it is difficult to confuse it with (C).

So, you need to trace which pin goes to 22 uf capacitor in the initial scheme of your clone and there will be luma

[Cristián Molina]

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... 

[Sanyameloman]

You know, I've never faced clones with such variety of switches "in stock": two quartz and two 4-position switches Usually clones we meet in Russia have 1 quartz for PAL (17.... MHz), O/J and N/P switches of 2 positions each or just one 4-position switch for regions. There may be contacts for another 4-position switch which are shortened by solder balls to provide one single mode (PAL 50 as default). E.g. if you need PAL 60 you just shorten the contacts in a different pattern.
Did you try to make different combinations of these two switches that you have? Maybe there is problem. Otherwise, check the soldering, make sure that all switch pins are soldered securely, there is no ring cracks around the pins or loosened contacts.

[Cristián Molina]

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.

[as32888]

Матчасть подучи

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Кстати, БП на 5 Вольт, что настораживает немного. Но если импульсный БП, он умеет коэффициент заполнения импульсов, близкий к 100%, и тогда сега получит свои почти 5 Вольт, а с 7805 трюк не пройдет, вероятно.

На своем опыте припоминаю, что sm801-a1 работал и не зависал при снижении питания до 3,3 В, а, может быть, и ниже, но при этом размах видеосигналов уменьшается.

[Sanyameloman]

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?

I think the only way to check it is to test your S-video mode, and make all the suggestions afterwards) Please let us know about your results

[Cristián Molina]

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.   

[Sanyameloman]

Hmmm... I'm currently working on S-video mod for TCT6001H clone and I've checked both of the schemes that I'd posted here and both of these schemes provide image.
I cannot see the exact wiring of your thingy so I only can make some suggestions.
1) The transistor you used in the scheme is C945 or its NPN analog?
2) Is everything okay with power and ground?
3) I'm very far from a mastermind's degree in electronics but despite the fact that the mod is fed from 5 volts you've reduced the resistor nominal by ~30 percent (2k instead of 3.3k). I think it's not the key issue but, IMHO, it may affect the result when it will be.

[Cristián Molina]

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.