I just got my RGB to S-Video/Composite converter and it works very nice... thanks again Mangelore!! I ordered from the guy Mangelore mentioned. It was $25 + $13 shipping. Shipping took about a week but I'm not gonna blame the seller, all things considered.
The converter also came with: Composite, S-Video, and DC Jack cables. Note it does not come with 12V DC adapter. Also included was a specification sheet. It says (amongst other things) that it operates on 8 to 15 V DC.
To test it, I went to RadioShack and bought a 9-pin male D-sub connector, matching housing, and a pack of 9V battery clips. About $8 with tax. The one thing I really needed I could not find: a post connector :mad: The device has two post connectors. One is 'large' with all input signals except V-Sync. The small one has all input signals. Since they didn't have any post connectors :mad:, I used some in-line crimp connectors. Needless to say the video-in wiring looks really bad...
After hooking up the device I powered it on and ... nothing! After double checking my wiring and testing that Ground, RGB, H-Sync and V-Sync signals were reaching the device, I thought maybe 9V wasn't enough (or maybe the battery I was testing with was too old). So I cracked open a 1571 and borrowed its power supply. Connected 12V, powered it up and ... nothing!
I was getting worried at that point. I verified the power connection. Yep, 13.3V on the DC plug and the Positive was connected to the pin labeled +12V on the circuit board.
Then I remember the photo the seller had posted about how to connect the DC plug's wires... they were backwards from what I was using. I used a multi-meter and discovered the connector on the board labeled +12V was actually common to the ground. And the pin labeld CON only went to a diode which was reverse-biased with the polarity I was trying to use.
So I switched the polarity that the 1571 supply was feeding the device and... success! A color 80-column display
Next I set aside the 1571 and re-attached the 9V battery (with the right polarity). I turned it on and... success
At this point I was using the Composite output because the front of my TV only has composite video in. I was worried because the image was very blurry. (Previously I was using composite with the 128's monochrome output and it gave a very sharp picture).
So I crossed my fingers, climbed behind the TV to connect the S-Video cable, turned it on and... success: A colorful and sharp 80-Column display
Obviously I'm biased, but the Color S-Video looks as sharp as the monochrome composite. And it looks better, not just because of color, but because of brightness. With monochrome, the output was too bright with the standard TV settings (I would change from bright cyan to a dark color like blue to get a slightly dimmer but still 'white' text display). But with the Color S-Video, the brightness is perfect. The device comes with 3 pots to adjust R, B, and G signals but I didn't need to touch them.
If you have C128 and no 80-column monitor, I recommend this if:
1) You have TV with S-Video input
2) You have a good 40-column monitor -- meaning one with seperate chroma and luma inputs like the 1702 because seperate luma/chroma is exactly what S-Video is... Commodore was ahead of the home entertainment industry
3) You have a nack for simple electronic projects
Important point to remember: the DC Plug should be wired with a positive tip and a negative barrell (ignore the +12V marking on the board).
Next I'm gonna dig around for some diodes and resistors and see what I can do about intensity. I'll also use some diodes to build a bridge rectifier and put a big capacitor on it, then test it with 9VAC. I should probably get a case to hide my ugly wiring