Sega Master System S-video Mod?

[Lastcallhall]

Cool. if you're still having problems after that, if you can post pics of what you have, it would be helpful.

[16-bit]

Alright, I've tried with the 33 ohm resistor, and I'm getting the exact same problems. I tried to resolder the the chroma output, onto the actual chip leg this time just to make sure there isn't some kind of short, and still, nothing. What types of pictures are you going to need of this to have any sort of idea on how to help me?

[ApolloBoy]

Also, what's your capacitor orientation? It should have the negative leg attached to the chroma out on the chip and the positive side connected to one side of the resistor, and the other side connected to chroma out to the jack.

Actually it should be the opposite, with positive going to the chip and negative to your output.

And 16-bit, make sure you have your S-video jack wired up correctly. I've made the mistake a few times where I accidentally mixed up the chroma and luma and got no picture.

[16-bit]

If there's a chance that will help the colors being washed out, I'll give it a try. I've retried soldering everything but the S-video jack

[Lastcallhall]

Actually it should be the opposite, with positive going to the chip and negative to your output.

Um, no...

http://www.sega-16.com/forum/showthr...l=1#post294849

For chroma is easier :
Take the signal from the pin 15 and connect it to the NEGATIVE side of the cap, then put the 75 ohm resistor and there you go, another useful signal.

Works every time for me.

RE: Pics - everything you've done: solder joints, circuit boards, everything.

[omp]

Hmmm strange can this be confirmed the capacitor orientation? Page 8 of the CXA1645 datasheet shows +ve to the chip. The few times I have done it +ve has gone to the chip. The SMS2 AV mod (done this er, um lots) has the cap +ve to the chip. Would be interesting to know it works either way......

[16-bit]

So I need to have the resistor soldered onto the negative of the capacitor heading towards the chip, and not the svideo jack?

I'll upload pictures tomorrow if I have time, I have a philosophy midterm I've got to study for.

[Lastcallhall]

Hmmm strange can this be confirmed the capacitor orientation? Page 8 of the CXA1645 datasheet shows +ve to the chip. The few times I have done it +ve has gone to the chip. The SMS2 AV mod (done this er, um lots) has the cap +ve to the chip. Would be interesting to know it works either way......

So here's the deal:

Regardless of capacitor/resistor placement (pin 15 --> cap --> resistor --> Y out OR pin 15 --> resistor --> cap --> Y out), the impedance is the same: (1/2(pi)fC). The capacitor orientation SHOULD be positive to negative to y out, BUT since the circuit is at such a low voltage, you can get away with some negative biasing and be ok. But, to be on the safe side, use ApolloBoy's layout to err on the side of caution.

Per my electronics instructor w/ a masters and 30 years experience in the field.

[MEGADRIVE Jeroi]

I've got one more question here though, what about giving the SMS dual mono audio?

Dosent nearly every tv take mono signal from left channel and divide mono into 2 channels left and right? I don't mean true stereo or anything but most all tv's take the mono and divide it to both speakers.

[ApolloBoy]

Dosent nearly every tv take mono signal from left channel and divide mono into 2 channels left and right? I don't mean true stereo or anything but most all tv's take the mono and divide it to both speakers.

Not all TVs do that, and in my experience most of the TVs I've used didn't do this.