complete DUO S-Video mod

[kid_rondeau]

OK! Got it!
I wasn't satisfied with the distortion on the picture (however minute) so I did some circuit cleanup last night, including:

-I didn't bus all the ground connections together
-I brought the 1881 about 1cm closer to the 1645
-I didn't use a socket for the 1881 (not sure if this helped, but you never know)

After about three hours of work, I tested it, and it works completely perfect now. Huzzah!

[grahf]

Nice work man, congrats on the finished board. Its a great feeling when you finally get something working.

[nat]

Anyone know where I can get a cxa1645m? I see I can get the LM1881 from Jameco.

I don't want to order a bulk quantity of the CXA's, just 1 or 2.

So I guess if any member here has a couple extra they want to sell me... 

[PCEngineHell]

If yo don't have a local source check ebay. They get sold off and on there.

[nat]

There's one listing up right now. The seller has 135 of these chips, but he's asking $20 a pop plus $8 shipping. Needless to say, shipping something the size of a quarter domestically doesn't even come close to $8. Beyond the obvious raping on the shipping charge, $20 seems a bit high to me.

Or is this what I should be expecting to pay for this item?

[PCEngineHell]

Currently,yea,unless you have a local supplier that will let you pay slightly more then what they get them at in bulk.

You can also strip the chip off of dead Saturns and I think Ps 1 systems use them also.

[D-Lite]

There's one listing up right now. The seller has 135 of these chips, but he's asking $20 a pop plus $8 shipping. Needless to say, shipping something the size of a quarter domestically doesn't even come close to $8. Beyond the obvious raping on the shipping charge, $20 seems a bit high to me.

Or is this what I should be expecting to pay for this item?

That's about the going rate.  Unless you feel like buying 100 of them

[nat]

I bought everything else that I need to do this mod today.

I guess I'll go ahead and order a couple of those from that eBay seller.

I'm going to go ahead and build an encoder based on grahf's work early in the thread. I'm going to do the mod first on a core TG-16 and see how it goes. I might try my Duo next if all goes well.

[CkRtech]

Odd place for my first post, but -

I just bought into the TG16 world for the first time this week. The original U.S. TG16 should arrive any day now. It's pretty exciting. I have never owned a TG16 OR played a TG16. I remember the commercials for it - going to Babbage's and seeing it out on display. Never played it.

That day will come to an end soon as it gets added to the collection of game consoles and games. One thing I make a hobby is improving video output of VG consoles. I'm not a guru in the area at all - I just have an interest in it.

nat - I would like to hear about your experience modding the core TG-16. I have an external RGB -> S-Video solution for the Sega Genesis, and I wouldn't mind rigging up a cable on the TG-16 that allows it to use the Genesis adapter. I am not sure if the level of RGB output is the same for the TG16 compared to the Genesis or not. If so, it should be an easy mod.

Look forward to talking TG video output with you guys,
CK

[nat]

I haven't done much with regards to video on the Genesis, but I can tell you that if you're looking to do an external "mod" on the TG-16, there is an expansion port on the back where you can tap the video signal directly off the VDC. You can get both RGB and composite from this port. I am assuming you are tapping the RGB signal from the Genesis in a similar manner, so your method would probably work on the TG-16 too.

The mod that I am doing is internal-- I'm actually going to add an S-Video port to the machine itself. Ideally, I'd like to do a component video mod but I understand that would be a bit more difficult.

Anyway, here is the pinout for the rear expansion port:

AR GG 01 VM 32 30 27 GG 17 20 22 23 13 11 10 08 GG 05 03 GG VV VN VR

02 CD 35 34 VU 29 26 15 19 21 VJ 14 12 VG 09 07 06 04 24 VT 37 36 VP

AL VV VS 33 31 28 25 16 VL VK QQ VI VH QQ VF VE VD VC VB VA GG VZ VQ


The pins you'd be interested in are:

VR -- Blue RGB signal
VP -- Green RGB signal
VQ -- Red RGB signal
VN -- Horizontal sync signal
VZ -- Vertical sync/composite video feed
AR -- Audio Right
AL -- Audio Left

All "GG" pins are ground.

I've personally never done anything with an RGB signal from one of these machines, but I have rigged up a few connectors over the years so I could use standard A/V cables for stereo sound and composite video on a core system that only has RF out of the box. Since I absolutely refuse to touch RF.

[nat]

And BTW, forum member D-Lite does TurboGrafx mods as a hobby. If you wanted to get your system "professionally" modded, he's the guy for the job.

[CkRtech]

I've actually talked via e-mail once before with D-Lite. I had some bad luck with the CXA1145 chip in my Model1 Genesis...

Hmmm....the Genesis uses a single composite sync that carries the combined Horizontal and Vertical Sync information rather than the separate sync info like the TG supplies. I assume these can be combined by tying them together - possibly with some resistors in the mix. Not certain.

Is that expansion connector a "standard connector" of any one type by chance? I don't have the TG16 yet. I look forward to getting it and investigating mod possibilities. That's quite a bit of useful signals on that expansion connector.

[nat]

Hmmm....the Genesis uses a single composite sync that carries the combined Horizontal and Vertical Sync information rather than the separate sync info like the TG supplies. I assume these can be combined by tying them together - possibly with some resistors in the mix. Not certain.

I think you can get the same result using just the VZ pin for sync and forgetting about VN, in that case. I'm sure D-Lite will correct me if I'm wrong but just VZ should be sufficient.

Is that expansion connector a "standard connector" of any one type by chance? I don't have the TG16 yet. I look forward to getting it and investigating mod possibilities. That's quite a bit of useful signals on that expansion connector.

Unfortunately, no. Not of any standard I've ever seen, anyway. I have extensive background in computer electronics and it's not used on anything else I've ever dealt with. As far as I know it's a proprietary connector.

The easiest way to tap signals off individual pins is to use an old SCSI/IDE ribbon cable and slice up the connector to effectively create single pin headers with a decent length wire attached. It's extremely easy to separate the wires on a ribbon cable. This is how I created my "custom" connectors.

[D-Lite]

I've actually talked via e-mail once before with D-Lite. I had some bad luck with the CXA1145 chip in my Model1 Genesis...

Hmmm....the Genesis uses a single composite sync that carries the combined Horizontal and Vertical Sync information rather than the separate sync info like the TG supplies. I assume these can be combined by tying them together - possibly with some resistors in the mix. Not certain.

Is that expansion connector a "standard connector" of any one type by chance? I don't have the TG16 yet. I look forward to getting it and investigating mod possibilities. That's quite a bit of useful signals on that expansion connector.

Nothing standard about the expansion port connector unfortunately.  Your best bet is to get a cheap Tennokoe Bank 2 or AV Booster and pirate the connector out of that. 

For the sync signal to input into the CXA chips, I've had much better results stripping sync from the composite video than tapping pin #44.  Seems to come through stronger.

Hope I was able to answer whatever questions you had with the Genny stuff back then.  If not shoot me another e-mail

[CkRtech]

Hey D-Lite, thanks for your input. Looks like pcenginefx has a really great community here.

So did you use an LM1881 to pull out your c-sync? Seems like it is a useful chip to have around.

Do you know what "state" the TG16 RGB circuit is in at the point it reaches the expansion connector? I know that all these video game consoles liked to put some components in the SCART cables rather than have each RGB output be ready to plug. The Genesis output needs a 75 ohm resister and 220 uf cap before it hits "standard" RGB output. My external converter most likely expects the signal to be "pre 75 / 220" as it plugs directly into the Genesis DIN port, so my experiment requires I essentially match the native RGB output of a Genesis in order to use the adapter.

Any thoughts?

[nat]

The Turbo's native RGB output straight off the expansion port should be roughly equivalent to that of the Genesis.

Check out this page for some more info about pulling RGB off the expansion port:

http://www.gamesx.com/rgbadd/duorgb.php

I see it mentions an amp near the end of the article that uses a 75 ohm resistor/220uf capacitor combo. You'd undoubtedly be just fine using the same setup you've got for the Genesis provided you can construct some kind of connector.

[CkRtech]

Oh awesome. Things are looking good so far...

[flooby]

Hey folks.  I finally found a "cheap" source of CXA1645 chips.  I bought a couple of broken PS1 consoles off ebay and am in the process of stripping the chips out of them.  Works out to be about $10 per chip.

Unfortunately, the first one is not going into the duo.  I'll let you folks know how it works using the RGB out from the Genesis.

[D-Lite]

Hey folks.  I finally found a "cheap" source of CXA1645 chips.  I bought a couple of broken PS1 consoles off ebay and am in the process of stripping the chips out of them.  Works out to be about $10 per chip.

Unfortunately, the first one is not going into the duo.  I'll let you folks know how it works using the RGB out from the Genesis.

Saturns too.  Actually, I think the Saturn has the 2075.  And the Genesis model 3 has the 1645 in it.

Passing the RGB through those chips is also a nice RGB amplifier for the Turbo systems.

[PCEngineHell]

Both my Saturn first gen decks have the 1645 in them.

[Tatsujin]

are there any news or changes concerning the draft-schematic kspiff once did? would be great if this could be confirmed as 100% working

thanx a lot

[kid_rondeau]

are there any news or changes concerning the draft-schematic kspiff once did? would be great if this could be confirmed as 100% working

thanx a lot

Tatsujin,
I have built and can confirm the functionality of kspiff's schematic WITH THE EXCEPTION of pins 15 and 16 on the 1645...

On his schematic, he has pin 15 going to Y-out, and pin 16 going to C-out. But the circuit should be wired OPPOSITELY. (Although, interestingly, the pin numbers listed are correct, e.g.: Pin 15 does go to Pin 4 of the S-video socket, and Pin 16 does go to pin 3 of the S-video socket. They're just labeled backwards.)

In other words:
Pin 15 from the 1645 must go to C-out, and pin 16 must go to Y-out.

It's not his fault that he listed it incorrectly; Sony's product data sheet contradicts itself.


The only other difference between the way he listed it and the way I built it is the substitution of an EC1881 for the LM1881N, which is a direct drop-in replacement.


Other than that, I built it 100% true to the diagram, and I can confirm that it works.

[Tatsujin]

thanx a lot kid^^

shame on sony and its unproper documentation

as soon as i got the parts, i will start with it.

[CkRtech]

Has anyone thought about designing a board for this and getting it printed? It would certainly help keep things neat and tidy when putting the board together.

It may also be helpful to have a "video game S-Video" FAQ as it seems there are plenty of systems you can use that 1645 with. I don't know if there is a FAQ out there yet or not. ....maybe I'll write one. I would be very tempted to fill it full of anti-1145 propaganda, though. I can't stand that chip....

[PCEngineHell]

Same here,I also cant stand the AD724,the favored chip of the Neobitz,useless piece of shit of the encoder world.

[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.

/indexfixed.th.jpg

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 isn't 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 separator (because the cxa1645 doesn't like the sync output from the HU6260 chip, so we strip a clean signal off of the composite video).

I made up a little elementary 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:





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:




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.





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:

[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.