S-Video Modded TG-16 not syncing - Anyone want to help me take a stab at this?

[Lastcallhall]

Connect them in series and wire them like this:

Gnd --|===|--#--|===|--- CSync
       680   |   10k
             |
             |---||---» LM1881 CVideo input 
                .1uF

LOL @ ASCII schematic :V

Take care, I edited this message like 4 times

I found out that I was tapping into the wrong signal on the EXP port, so I fixed that and tried again...

... It still doesn't work, but I think I have it narrowed down to the chip...

I purposely left the leg on the 10k resistor connected to composite uncut and when I connected it directly to the composite out, it stabilizes the picture, but the colors are all out of wack. I tried to take a picture and video, but it doesn't come out the way I see it in person. Anyway, I'm fairly sure that the CXA chip is the culprit, as I can get a solid sync signal from the EXP port, the C6260, and from the composite out on the EXP port, as well. So, what I'm going to do is I'm going to order a new CXA1645 from a stateside dealer and just redo the entire circuit. This may take some time, so I'll check back in once I get that done.

[Jorge Nuno]

Before ordering the IC, does your current encoder kill the Sync signal: forcing it to 0V? but holy shit, $15 for a video encoder? I can buy FPGAs at that price and do video encoding by hand (not that I want to, though)

[Lastcallhall]

I'll double check, but that's what it seems to be doing.
::measures from sync out to ground::

I'm only getting 40mV out, but it's holding steady.

RE: Encoder - yeah, the only dealer that I can find online sells them for 10 bucks each, plus 5.95 shipping. =\ I could pull one from one of my dead PS1 units I guess, but I'd rather have a new chip.

[Chilly Willy]

Ugh! I hate bad parts... reminds me of when I was in the Skills Olympics - I did well on the theory part, but when it came to the practical, I got bad parts, and when I identified the bad parts, they replaced them with MORE BAD PARTS. Now, when you replace bad parts, would you even think to test that the replacement parts are also bad? Especially in a contest? By the time I figured out the replacements were also bad and got replacements for the replacements and verified they were good (I was paranoid by that point), it was too late to place well in the contest.

I've still got the contest project - a digital clock made from an 8048 (designed by Intel for the Skills Olympics). It works great, even though it's almost three decades old.

[Lastcallhall]

It works! Thanks to TheSteve and Apolloboy over on the PCEFX thread, I finally got it to work:

ya could go simple, and just pull S-Video right off the huc6260

the cap is 0.001uf
the transistor i tested with is an S9013
40 is pin 40 of the huc6260
comp is anywhere you can get composite video (I tapped the vid pin on the RF modulator)

You could try a 2N3904, it's an NPN transistor like the S9013 is and it usually comes up as an S9013 substitute.

15 minutes later I'm good to go! Once I find my capture card I'll display some comparison pics.

[eddiespruce]

You got it working, way to go, man!

Here's some rep for a job well done.

[MEGADRIVE Jeroi]

Nice thing. I just say that unfortunely there was no one in sega-16 to help you so some other geek forum did beat us :/

[Chilly Willy]

Well, we were trying to FIX what he had, not replace it with something entirely different.

[Lastcallhall]

Some comparison photos. S-video is on the left, composite (pulled from A23) is on the right:













(This one I may have picked a different court between the two)


EDIT: Higher resolution shots available here:

File name: Comparison.zip File size: 1.65 MB

[Xian Xi]

For the 1645, did you try adding a 0.1uf cap on the sync input?

[ELabit]

Awesome dude! thesteve is the man, he's done a lot for the pcefx crowd lately and has solved a lot of modding problems everyone else had given up on. I just got my RGB up on a PVM and it's incredible the difference. You don't realise how bad composite is till you see it side by side to svid or rgb

[Guntz]

You know I'm still quite impressed by the TG16's composite. It's unusually crisp and insulated.

Dumb question, but it'd save me some time. Was this S-video mod done with a new video encoder or with the original encoder (ala Genesis S-Video)?

[Phosis]

I believe this is the unit that was sold to me...I received it today and tested everything. To be short; it looks bloody fantastic.

[Lastcallhall]

For the 1645, did you try adding a 0.1uf cap on the sync input?

No, but that's something I'll try for an upcoming mod.

You know I'm still quite impressed by the TG16's composite. It's unusually crisp and insulated.

Dumb question, but it'd save me some time. Was this S-video mod done with a new video encoder or with the original encoder (ala Genesis S-Video)?

The composite is nice and bright, but if you look at the higher quality comparison pics, there's a lot of noise around the sprites and backgrounds. I'm thinking a cap attached to the video line might improve things, but I'm just guessing at this point.

Also, in answer to your question: the chroma and luma were both pulled from the internal hu6260.

I believe this is the unit that was sold to me...I received it today and tested everything. To be short; it looks bloody fantastic.

It was. Glad you like it.