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

Hey all - I'm going to cross post this over at PCEngineFX, but given the wealth of talented modders here, I thought I'd post in this forum, as well.

Long and short of it is, is that I bought a Duo-R a couple months back to replace my TG-16/Turbobooster combo I've had for a little over a year. Well, the Duo is in need of a CD lens replacement, so in the mean time I thought I'd try and mod the TG-16 for s-video and audio out, and see what comes of it. I was able to look at the documentation shown over at GameSX.com, and from there took the proper signals and fed them into the CXA chip, composite signal included, on top of adding a region chip (Obey chip from BlueBMW and TheSteve from pcenginefx) and reset button. Once I had everything hooked up, I powered it on and got this:



As you can see, the sync signal seems to be trashed. I've done a little research and found the following:

1) The sync signal from C23 on the EXT port is labeled composite sync, as is pin 44 on the 6260 CPU of the TG-16
2) Knowing this, I purchased a LM1881 Video sync seperator, and fed the a) the composite signal from the EXT port, b) the composite sync signal from the EXT port, and c) the composite sync signal from the 6260 into the chip (all at different times, obviously), hoping to get a clean sync signal out of any one of them, but no such luck. This was actually suggested by someone over on the PCEFX forums.
3) I have several 4558D OP AMPs lying around from an earlier CCAM mod attempt, but I'm not sure if I can use them to amplify this type of signal. even so, I don't have the slightest clue as to how to get it done.

I'd really like to get this up and running (and sold...), but I seem to have hit a wall on this. I'm half tempted to take it to school so I can look at it all in a lab with proper test equipment, but if I could solve it prior to that, it would be even better. So what do you all think? Any help is always appreciated. Thanks!

Which CXA are you using?...

1645.

What do you have for the "Scin" input?...

Also, do you have pin 9 with a 0.1u coupling cer cap?..

Quote:

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Originally Posted by ooXxXoo

What do you have for the "Scin" input?...

Also, do you have pin 9 with a 0.1u coupling cer cap?..

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Subcarriers is the standard 3.579545 MHz oscillator, pin 9 is grounded w/ a 0.1uF cap.

Buy a cxa2075 they're way easier to get working.

I've thought about it, but I've already sunk a ton of cash into this system; I'm hesitant to spend more until I know what the root of the problem is...

A quick update:

I took the csync signal from the 6260 and added it to the composite out jack on the system and the image stabilized, albeit in B/W, which leads me to believe that the sync signal is good on the system, I just need to rework the CXA1645 circuit - something must have gotten messed up somewhere.

Parent/teacher conferences tonight, so I doubt I'll get to this until morning, but I'll figure it out...

Which cuircuit are you using to amplify RGB/sync?...

If you haven't, keep in mind that you have to amp these signals prior to feeding them to the CXA as they are too weak on their own...

Yeah, I just noticed that there's a RGB/sync amp circuit on the gamesx website that I didn't construct before.

Back to the drawing board...

cxa1645 has a built in rgb amp. Usually you need to amp the rgb signals from the rgb nes ppu but if you wire it straight into a cxa1645 it gets amped anyway. The cxa2075 also has a built in amp.

Sync I don't think would need an amp you can wire up a lm1881n circuit for sync if you're really concerned with it. Again this's something I learned from experimenting with rgb nes systems.

So here's what I was told on the PCEFX forums:

Quote:

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lastcallhall, seriously, stop jumping around all kinds of hoops and just go with the LM1881. It's pretty much the standard way to do this, and it works. Everyone uses it for everything. Here is a picture of a circuit from the gamesx page:

Original link: http://www.gamesx.com/misctech/lm1881.htm
http://www.gamesx.com/grafx/lm1881.gif

It's incredibly easy, and you only need like 50 cents worth of components. You are ONLY going to use pins 1, 2, 4, 6 & 8.


Composite out is pin 1, which is what you're after. This goes into your CXA1645.

Composite Video goes into pin 2, NOT composite sync from the HU6260. The easiest place to get composite video is off the back of the original AV out plug. Just solder a wire to the right place on the inside of your Duo. You need to put an 0.1uf capacitor in-line, which looks like this: http://www.newpages2u.com/images/128...2142f88ecc.jpg and will say "104" on it.

Pin 4 goes to ground. Make sure the LM1881 and your CXA1645 circuit share the same ground. The grounds for everything should end up connected to the ground on your Duo's motherboard.

Pin 6 is the "set" pin. Not reset. You need another 0.1uf capacitor, the same one as above. You also need a 680kohm resistor. Make sure the value is correct. You hook both of these parts to pin 6, then the other side of them goes to ground. The same ground as everything else.

Pin 7 is 5v input. You can use any value up to 12v, but it's easy enough to get 5v off of the Duo motherboard, and I personally use 5v.


Good luck, and if this still doesn't work please post pictures of what you have currently made.

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It didn't work, and here are my results:

:?

Still didn't work.

Here are some closeups of what I'm looking at:

Here's the LM1881. Solid green is video in from pin A23 on the EXP port, striped green is sync out, solid blue is 5V in and the two striped blue are tied together and are connected to ground.
http://img.photobucket.com/albums/v4...l/bd2fd2ca.jpg

Here's a shot of the voltage regulator. You can see the striped blue wire coming from the LM1881 to the center pin which is ground, along with another ground wire from the CXA1645, as well as the solid blue 5V wire from the LM1881, and the 5V line from the CXA1645 (Will show shortly) connected to voltage out, which should supply a 5V voltage to all components.
http://img.photobucket.com/albums/v4...l/6baf5fbb.jpg

Here's the CXA1645 itself. Pin 1 is grounded, pins 2,3,&4 are RGB respectively, pin 5 is No Connection, pin 6 is connected to pin 3 of the oscillator (shown above the IC), pins 7, 12, & 19 are all tied together, and fed into pin 4 of the oscillator, which is connected to the voltage out on the regulator (shown in the previous pic). Pin 8 is no connection, pin 9 is grounded, and pin 10 is sync in. Pin 11 is no connection.
http://img.photobucket.com/albums/v4...l/91cf419e.jpg

Bottom half of the 1645. Pin 13 is connected to a 47KOhm resistor and a 0.1uF capacitor, which are then each ran to ground. Pin 14 is connected to a 10uF capacitor connected to ground, while pins 15 and 16 are connected to a 75ohm resistor and a 220uF capacitor in series each, connected to chroma and luma respectively. Pin 17 has no connection. Pin 18 is connected to a 20kohm resistor out to ground. Pin 19 has been discussed earlier, pin 20 is also connected by a 75ohm resistor and 220uF capacitor in series out to composite out. Pins 21, 22, & 23 are not used for this circuit. Pin 24 is connected to ground.
http://img.photobucket.com/albums/v4...l/58f0127d.jpg

Here's a shot of the ground wires all bundled together and fed into a single wire for organization's sake (note: my finger is on the composite out wire; the striped orange wire ABOVE my finger is connected to the bundle of wires running to ground:
http://img.photobucket.com/albums/v4...l/e9bbf757.jpg

So... here we are.

Any thoughts?

Is there any place onboard where you have a working sync or video?

Jorge! Haven't seen you in a while!

From what I can tell, I can take the csync signal from the C6260 chip and feed it into the composite out and the image stabilizes, but it's a B/W pic (obviously). I haven't tried the sync signal from the EXP port, because everything is screwed and soldered in place so I don't really have access to it. I'm going to try and take the sync out from the LM1881 here in a bit and connect it to the comp out and see if I get a steady signal or if it still scrolls. If it does, I'm guessing it's the chip that's screwy...

Ohh so you do have a CSync source onboard. This makes things easier :P Do you have a multimeter and 2 resistors around the thousands of Ohms?

I never looked into this system so I'm gonna ask some simple questions:

Where does it's video come from? Is it directly from the VDP? Does it work fine?