complete DUO S-Video mod

[CkRtech]

Alright. That's it. I'm writing an S-Video mod FAQ for multiple consoles - starting with the Turbo/PC-Engine. It's about time one gets made. I've been running around newsgroups, google, neogeo.com, atariage, benheck, and now pcenginefx too much.

If someone knows of one that has already been made, please let me know and I'll save myself some time.

[nat]

No one has written a FAQ for the Turbo.

That would be great for all the DIYers out there. Can't wait!

[CkRtech]

Those of you that ordered from Mouser or Digi-key or wherever, would you mind posting your part numbers that you used when ordering? If you have the e-mail or invoice filed away somewhere, do you mind dusting it off.

I am going to try to put together that S-Video FAQ and it might get paired with a how-to depending on how ambitious I am. Since I am going to gear this toward Turbo consoles, I might as well take the time to modify mine as I write the guide.

After I get a good idea of part numbers, I will probably order those exact numbers and then use them in the FAQ to make it easier on those that need a grocery list.

I personally started filling up a cart on digi-key...but I don't know if that is the route I want to go or not.

[Jitawa]

If someone could put up a copy of the trace for the little project board part, then people could just print the PCB themselves and just insert the parts in the appropriate holes:
http://www.5bears.com/pcb.htm
Well, if they had a laser printer, but maybe you could do it at Kinko's or something.
 :-"

[Duo_R]

Any updates on the guide? That would be awesome if you could put that together!

[Duo_R]

bump - BTW I ordered a board that is designed to make soldering to SMT pins easier. Will see if this will work with the CXA1645 chip from a Sony PSX.

[CkRtech]

Hey Duo_R -

No updates on the guide. I collected a lot of information, got sidetracked in messing with SCART/Component video options for various consoles...and then had Hurricane Ike hit. ....someday...

[Duo_R]

just a correction to the diagram that was previously made by Kspiff. Corrections to the Y and C pins.

Kspiff, first of all welcome to the forum! Secondly, good job on the schematic. You saved me the trouble of finishing mine. As far as I can tell, everything is 100% correct. You did fine on the LM1881 also, the CXA1645 likes the composite sync input fine. The actual construction of this encoder isnt really hard, but its difficult to understand what goes where if your not familiar with electronics schematics and terminology. Plus, soldering to the SMD cxa1645s is a bitch. You really only need a few things:

cxa1645
Assorted ceramic caps.
Assorted electrolytic caps.
Assorted resistors.
The 3.579~ oscillator (makes the output of the chip NTSC).
LM1881 sync seperator (because the cxa1645 doesnt like the sync output from the HU6260 chip, so we strip a clean signal off of the composite video).

I made up a little elementry level chart for those who are unsure what the symbols on the schematic mean:

[Sensato Black Lion]

I just finished performing this mod for myself. Congrats to everyone who worked on this project!

Before trying the mod on a Duo (was kind of afraid I might damage the Duo if I did something wrong), I tried it on a US TG16. Built the circuit and tried it out. The result was a sharper picture but with a lot of bleeding and color distortion. Double checked everything on the CXA board and everything seemed fine. I then decided to build a second CXA encoder pbc. Obtained the same bleeding and distortion. Double checked everything once again and everything seemed fine. Thought the problem might be on the TG16 itself so after a dozen hours of work, I connected the encoder to my Duo and powered it up. IT WORKED JUST FINE! Hurray!!!

S-video vs composite on the PCE doesn't make a difference as huge as I expected (not as much a the Genesis s-video vs compsite anyway) but it still is really great to have a sharper, less washed out picture on screen. I've been looking for a PCE s-video mod like this for years!

Anyone else had problem with this mod on a Turbografx system or is there really some problem with the system I have? I'll eventually be able to try the encoder on another Turbografx to see if the problem comes from my system or not.

With S-Video on your Duo do see any faint vertical lines kinda like this?



The above image is an exaggeration, but I have a very faint version of those lines with my system.

I actually have these faint lines which I noticed for the first time on a white screen. Unless a white screen shows up, I can barely see them.

I have also noticed that in the Kaze Kiri option menu, the blue background is kind of wavy (not the text but only the blue screen). There is some slight pixel movement in the blue color when compared to the composite output. Maybe this is normal thought... I'll perform more tests soon.

[SNKNostalgia]

The faint lines on white backgrounds and the wavyness/RF like interference on solid blue backgrounds is always going to happen with PCE/Duo S-video mods. The RGB coming from the GPU just comes out that way. Mostly you just get rid of the shimmering, rainbowing and dot crawl with the mod. It is still worth it in every way. I also noticed that if you use a shorter S-video cable, it comes in a little stronger and there is no dot crawl at all on the blue backgrounds you mention. Avoid S-video selector boxes if you can.

[chop5]

i took a gander at this mod following the revised schematic to the T. worked great and thanks kspiff,graf,duor,nat and everyone else for all the helpful info.

Making the pcb was quick and easy,just a few hours but what took a heck of alot of time was locating and ordering the parts. between digikey,maouser and ebay months had passed. this is what i made for a client(named withheld for anonymity)

i was gonna make 3 test boards each with different chips and components bought from multiple sources so the chance of failure would be slim but time was running out so made 2.

board 1:

http://img.photobucket.com/albums/v238/jetbue7/chiptopus.jpg
http://img.photobucket.com/albums/v238/jetbue7/board1finished.jpg
http://img.photobucket.com/albums/v238/jetbue7/board1back-1.jpg

chip harvested from a dead ps1,cxa1645 chip surface mount. snowkitty helped in the harvest.
the chip was wired to make it easy to handle. Both boards were done with common telephone wire braided and solid core chosen for its durability.

board 2:

http://img.photobucket.com/albums/v238/jetbue7/board2finished.jpg
http://img.photobucket.com/albums/v238/jetbue7/board2back.jpg

done with a DIP cxa1645 chip,larger for easy soldering.

this was a prototype so i can just drop in a chip of my choice and solder. pre wired board but was to big so it was scrapped.

http://img.photobucket.com/albums/v238/jetbue7/protoboard1.jpg
http://img.photobucket.com/albums/v238/jetbue7/protoboard1back.jpg


i had to use my own breadboard cause the one suggested was way to small for me to use. to make more wire and connections i drilled some of the breadboard holes larger.

The boards were sent untested to my client cause they were meant for a duor or rx. i didnt want to test them on my american duo cause the chips are on the bottom and will be difficult. So i prayed to the various gods and goddesses that at least 1 will work.

client plugged in board 2 first and it didnt work. found out from my pics i soldered on some wrong pins 
he fixed the wrong pins but still a mess of a picture. I figured cause of my mistake the chip fried as soon as it was plugged in. mmm fried chips 

client plugged in the first board and it worked great after some ground tweaking.
So i can be witness that the schematic here works great and the mod. will be making a few more boards and do more testing. hopefully smaller boards than the monstrous ones i made



a rough drawing of the layout used for them:
http://img.photobucket.com/albums/v238/jetbue7/layout.jpg

[BlackandBlue]

Glad to see so much success with this mod.  I think I might try this out with my TGCD unit next time I'm bored    Thanks for all your work guys!

[nat]

How important is the 0.1uf capacitor connected to pin 13 on CXA1645M before it goes to ground? What is it even for? I didn't have one on hand, so I built my latest encoder with 1uf in its place because it was the closest I had... I know you shouldn't do that, but I can't figure out what this particular capacitor is even used for. It doesn't seem very important IMO. However, the joke's on me because the encoder outputs no video. I find it hard to believe substituting a 1uf in place of that 0.1uf would be the cause, but I thought I'd check to be sure.

If that's not the cause, as I suspect, I've got something else going on. Which is a real bummer because everything looks good and I've triple checked all my connections. I'm trying to mod an RAU-30, which I've never done before, to avoid cutting into my SuperGrafx.