Modding the Snes so the Tototek GBA-SNES adapter does not need separate AV cable.

Would this work:
http://www.ebay.com/itm/OMRON-G6H-2...US_Motherboard_Components&hash=item19e1fe8efc

Also could I use a 2n7002 since the 2n7000 doesn't have an SMD package.

 

I think It should. Btw, ive updated the schematic on the first page with parts for my audio fixes.

 

I also updated that pcb I showed you to have that audio fix which wasnt much to add to the board but works fine and hopefully other people try it out so we can have feedback and adjust the design as needed.

 

I tried getting a video transcoder on the very cheap, to test how composite to Component or S-video performs in everyday life.

In other words I raided an electronic repair shop Dumpster and ran off with a couple Panasonic DVD/VHS recorders

One of them had psu issues but the other one seemed to only have DVD trays problem. I connected Composite on the video input and It outputs S-video and Component on the other side. However result is not very good. I get a little lag, some screen tears and the resulting video is interlaced. Maybe this thing has some hidden menues. Maybe I should start a thread on video transcoding, I am suddenly interested by the subject.

 

That's all? I once took an entire truck load of PC stuff from the junkyard behind a PC repair shop.

...with permission of course...

 

My place is already crammed with various junk, so I was selective.

 

If you're getting lag, then almost certainly the image is being processed digitally. Not ideal.

 

Yeah thats what I figured.
I made some research And bought this thing off ebay:
http://www.ebay.ca/itm/Extron-YCS-Composite-SVideo-Transcoder-6032301-/121164514072

I also found this file which is an archive for a DIY YC separator + video enhancer box!
That's kinda neat me thinks, it even comes with the etch patterns for the board
Just uploaded it to my dropbox
https://dl.dropboxusercontent.com/u/43851675/video enhancer & yc separator.rar

 

In the meantime I made some semi random experiments with passive YC separation. Namely an inductor for Luma and a cap for chroma

It kinda works but no matter what values I use its always a compromise between blurry picture and checkboard effect. Just the composite looks better.
Im done with that for now, until I get my new gadget from ebay and see how well it works.

But basically its a nail in the coffin for the idea of a simple YC separation to make a more universal version of this mod.

 

First of all thank you very much to MaxWar (and his little helpers here) for the great work on the mod

I've done the mod for a friend of mine with a PAL-SNES (2Chip-version). I used the second schematic on the very first page here plus the mute-part of the first out of the first schematic.
As I observed some problems with the NAND-gate I've used I descided to replace the IC with a microcontroller doin' the switch on every power cycle. The microcontroller detects the adapters flawlessly.

I can measure the same waveforms of composite video from the SNES (in case of a 'normal' catridge inserted) to the circuit-output as well as of the tototek adapter at the expand-line to the circuit-output. However, the composite video of the adapter seems to be very week and my TV can hardly detect the signal. This results into a very very weak and bad picture on the screen...

Has anybody a solution for that?

Best Regards

 

I think it is pretty awesome you went and built that.
I think you are the first person to actually try to build it. To be honest i am not sure It is a mod I recommend, its is quite complicated and finicky.

I made that mod to challenge myself if anything. This mod, while it works, is kind of crude.
As I understand, you are using the Composite only version, well, I made a schematic but did not actually try it so I have to tell you my friend that you are actually prototyping it xD

What I can tell you is that I had some problems transmitting video signals through the transistors, they would downgrade somehow on my S-video lines, this is why i ended up using small relays. It seems I did not have too much problem with the composite from the adapter though, but then you are in PAL region so things might go a bit differently. Does the adapter works good when used in the intended fashion with the separate cable?

 

The adaptors work fine with the 'normal' cable. I do the mod for a friend of mine who loves these adaptors

I will upload some pictures of the mod as well as from the measurements I did quite soon. Maybe someone has an idea what to do... (I'm at work now)

However, just a few words:
- S-Video is something nearly nobody uses here in the PAL region. So I just think of simply 'cut' these lines anyway in a next step. Although I don't think that this should be the problem.
- The video signal propagates well through the transistors. I've used the 2N7002 as the 2N7000 are not provided in a SMD-package.
- The Vpp of the CV-signal of the adaptors is just half of the Vpp of the CV-signal of a normal catridge... So I think of adding an aplifier right before the first transistor.

 

When the AD adapter is being used you should have a solid 5V at the base of Q2, can you confirm this is indeed happened as expected?

Also, as I check my schematic again I do not remember why I put that C1 capacitor, seems a pull down resistor might be used there instead.

 

You guys are so wonderful. Thank you for all the research!!!
It´s really unbelievable how much effort borti4938 has put into this project.
It would be a shame if it turns out to be a failure...

GOOD LUCK AND I KEEP MY FINGERS CROSSED!

Stefan

 

I just noticed the other day that there is a new version of the AD Adaptor, it's white and comes with an SD based flash cart. I wonder if it works differently.

 

Hi there,

here are some pictures of the mod I've done and the measurements (inside the spoiler)... Note that is an experimental setup so far.

I have lift composite video (out) pin of the S-ENC on connected the output of my PCB to the pad (or better to an appropriate via).

Spoiler

here are the testgames:



F-Zero:


The Adapters:

As mentioned: The video signals passing through the transistors quite well. There is no problem at all. The PIC detects the adapters very well - it is programmed that the detection is during the first second of a power cycle. Afterwards the PIC goes into sleep-mode. Hence I do have solid 5V at the base of Q2 in case of an adapter is inserted.
I think I've read somewhere here that you have added the capacitor C1 because of some interference noise reduction. A pulldown resistor would be miss-placed there

The only thing I can see at the moment is that the Vpp of the adapters is half of the Vpp of F-Zero... So I will try to insert an amplifier, which will hopefully does the job.

The PCB as well as the code for the microcontroller can be taken from this downloadlink: download me

 

What does not make sense to me is that the composite video from the adapter should only go through a single component, the transistor. So without the influence of this component the signal should be identical to what comes out natively out of the output jack of the AD adapter, and you said to me that it works as itended when you use that output jack.

So if we eliminate the transistor that leaves a few possibilities.
1. Your ad adapter is somewhat different than mine and does not output video signal at the same level through the cartridge slot as it does through the jack output.
2.There is something connected to the expand line that affects the signal : IIRC on my snes the only thing connected there was a pull up resistor, that is all. Otherwise it goes to an unused pin of the expension slot.
3. Even with turned off, the transistor that should be shutting down signal from the S-ENC still emits a little something that has a deleterious effect on the signal from the adapter.

Edit: 4. Is is possible that the microcontroller leeches some of the signal?

 

Wow - the last point was very good !!! Can't believe it that I never tested the 'normal' cable of the adapters with the microcontroller installed. I tested it a few seconds ago and... it also don't work anymore.
The last test was with the 74HC00 where the 74HC00 made a lot of problems. Shame on me that I forgot the test with the microcontroller.
I'll put a high valued resistor inbetween of the expand-line and microcontroller.

 

Maybe you could try the RetroPORT NES Adapter or RetroGEN Mega Drive Adapter - all worked fine to me.
Additionally I also have the mobile SNES Clone Retro Duo Portable from the same company. This device passes through the video signal without any modification.
If you want, I can also send this SNES clone for testing purposes...

 

That might just work!