Video Cable

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IMPORTANT: This main article refers to an NTSC TI-99/4a console. The European model used a different 6 pin plug. For details please see the end of the page.

These are instructions for making a video cable to replace the RF Modulator that came with the computer. Whereas the RF Modulator connected to the antenna leads of a TV, this cable will connect to the RCA audio/video connections of newer TVs, VCRs, PCs, etc. *

Parts List

  • 5-Pin DIN Plug (Radio Shack Cat No. 274-003A)
  • Set of RCA type connectors (one for video and one for audio)
  • Solder (use a fine electronics grade solder, NOT the plumbers type)
  • Soldering iron (30W seems to work well for me)
  • Wire strippers
  • Diagonal cutting pliers
  • Ohm Meter (for testing the cable)
  • Some type of clamping device (to hold the plug still while you solder it)

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What To Do

  1. Cut the RCA connectors off of one end of the RCA cable. This will expose the wires for us to work with and leave a set of RCA connectors on the opposite end.
  2. Strip 1/2 inch of the outer casing away, exposing the center conductor surrounded by the grounding conductors.
  3. Cut away about half of the grounding conductors so as to decrease their quantity and enable us to fit them in the DIN plug.
  4. Strip away about 1/4 inch of the insulation on the center conductor.
  5. Repeat steps 2 to 4 on the other cable.
  6. Tin the center conductors of both cables (apply a thin covering of solder to the. This will make it easier to join the conductors to the plug.
  7. Twist the ground wires from both cables together and tin them also.
  8. You should have three wires to work with, a ground and two center conductors.
  9. Cut the tips of all the wires to make a clean and even connection.

Connecting The Wires

You must use caution when applying heat to the pins as the plastic holding the pin will melt if it gets too hot.

  1. Apply a small amount of solder to the inside of pins 2, 3, and 4.
  2. Heat pin-3 until the solder melts and insert one of the center conductors, remove the soldering iron and allow to cool.
  3. Repeat step 2 for pin 4
  4. When connecting to pin 2, you will use the ground wire not the center conductor
  • Pin-1: Unused
  • Pin-2: Ground Connection
  • Pin-3: Audio Connection
  • Pin-4: Video Connection
  • Pin-5: Unused

Testing The Connection

  1. Use an Ohm meter to test the continuity between the pin and the other end of the cable. If you do not get a reading, then one of the connections is bad. Check the connection and reapply solder if needed.
  2. The things to check for are that you have continuity between the grounds on both RCA cables and pin-2 and that the center conductors have continuity from pins 3 and 4 to the respective RCA pins. You also want to ensure that none of the pins are shorting to any other pin.

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PAL Video Output

In Europe a different video output (YUV) was used to connect to an external PAL-G modulator. This used a 6 pin DIN socket. The sixth pin being in the centre.

     sound  o             o + 12V
                  o earth
         b-y  o        o vid (luminance)
                  o r-y

The connection for a monochrome monitor should be across pin 6 (earth), and pin 2 (video). The video is monochrome, colour is obtained using the colour difference signals.

Beware of earthing pin 3 (r-y) to ground which can damage the video output I.C.

The input impedance of the monochrome monitor should be fairly high (above 560 ohms) and not 75 ohms (which is a standard value), as the video output circuit of the console can be damaged feeding a 75 ohm load.

TI did not use RBG output in Europe so obtaining colour on a colour monitor from a European console is not easy but is possible with additional complex circuitry. A monitor with a "colour difference" input may work but do check impedances.