Thursday, March 17, 2011

Dreamcast: S-Video Cable DIY

I ordered an S-Video cable from Amazon for my Dreamcast. The cable didn't work though. The composite and audio channels were fine, but S-Video gave a crappy black and white, fuzzy image.
I cracked the plastic off the plug (on the dreamcast end) only to find that the S-video's chrominance and luminance cables weren't even connected to the right pins! Both wires running to the S-video connector were attached to the composite pin @_@

Wow; talk about spotty workmanship. Apparently, the creators of this cable had NO idea how the dreamcast pinout works.
Anyway, I re-soldered the wires, and eventually got the S-video signal I was looking for.

Making your own S-video cable for Dreamcast
(starting with a bad cable, though, due to pin restrictions).

1. You need to buy a bad S-video cable to make a good one. Unless, of course, you already have a dreamcast cable that has all of the pins in the plug. If you do, there should be 16-pins on the connector head. If there are only 4 or 5, then you can't use that :(

Here is a link to the bad cable I bought (ignore the picture. The actual item had all the pins):
http://www.amazon.com/gp/product/B001QVDSRO

2. Strip the plug off your video cable. The plastic casing around the end of the connector has lines along side of it, and if you gently pry with a sharp knife, it should just pop off.

3. The pins are staggered up and down. From your left (with the flat part on top) you've got pin 1. It goes in a zig-zag until pin 16 at the right. The pins you want to find are pins 11 and 12. This is S-Video Chrominance (C) and S-Video Luminance (Y). They should be right next to a connected wire(s) (pin 13) which is composite.

4.  Gently disconnect the composite wires from their pins (there are 2, and the wires later split into both the yellow composite plug and the s-video plug).

5. Plug the s-video cable in, and turn on the console (with no game in).

6. Plug the Dreamcast end in.

7. Now, you want to touch the two wires you just disconnected separately against pins 11 and 12. You're looking for a picture to appear. When the picture looks proper (the color and brightness look normal) then you've found the right wires.

8. Write down which wires goes to which pins!

9. Now all you have to do is solder the correct wires to the correct pins (from step 7).

I simply electrical taped my plug when I finished, since I had a more exploratory journey than the one I just described. If you can manage to snap the same plastic cover back onto your plug, that's awesome!


Note: 
The yellow composite plug is now useless. The reason being you just disconnected the wire from the composite pin. In order to have everything work with this cable, you'd need an extra wire entirely. A small tip for the adventurous: There are at least two ground wires (brown and black in my cable). You could rewire one into the composite if you want to, and then use the other as a universal ground. It didn't cause any problems in my experience. You'd have to reconnect some wires down the line though. I recommended just using your old composite cable when needed.

Links:
http://pinouts.ru/Game/dreamcast_pinout.shtml
http://www.gamesx.com/wiki/doku.php?id=av:dreamcastav

Wednesday, March 2, 2011

Using USB power in a pinch!

In my electronic repair experiences, I've twice has to find alternative power sources for cooling fans. One was an existing problem where the physical power connector on a laptop motherboard had somehow snapped off. The other was my own fault. I replaced the fan in my PS2 to reduce the noise, and accidentally shorted the leads (thank goodness for fuses; only the fan power was damaged).

To remedy both problems, I utilized an often forgotten power source: the Universal Serial Bus port. USB provides an easy source for 5 volts of direct current. This solution requires zero soldering (unless you really want to), and can be performed with a pair of scissors and a sacrificial Male-A USB cable.

Let's get started

1) First, snip the USB cable so that the MALE-A* size stays intact. You'll need enough length to reach from the external USB port (or you can solder directly to the port internally if you've got the ability) to the fan (12V-5V) you're powering.

2) Now take the Red and Black wires and strip the ends by about half an inch.**

3) Strip the ends of the fan's wire by about half an inch as well.

4) Now you'll want to plug in the USB cable, and test the fan. Make note of the configuration of wires that works. Mind the polarity! This is DC, bro, not AC.

5) Now unplug the USB cable.

6) Twist the correct stripped wire ends together, and then electrical tape them so that they don't come apart.

7) Install the fan, and then rig the wire however necessary to reach a port!


After Notes:

Plan ahead. Make sure you're going to be able to reach the port from wherever the fan will sit. 
Since the power is now provided by a USB port instead of the default fan connector, there won't be any dynamic speed changes. This can be very noisy! In the case of my PS2, the fan runs constantly, but is way quieter than before. The laptop was a lot louder, however, since the fan usually only runs when the CPU reaches a set temperature.