nessus@nsc.UUCP (Kchula-Rrit) (04/26/85)
[I found your flame verbose. You scream and you leap.]
The following shows how I connected a monochrome monitor to a TI 99/4A
console. This is dependent on the console having some jumpers on the CPU board
connected in a particular way, so it may not necessarily work on all consoles.
All schematic references are to Sheet 1 of the schematic diagram on Page 59 of
"TI-99/4A CONSOLE and PERIPHERAL EXPANSION SYSTEM TECHNICAL DATA".
First, check the resistance between Pins 2 and 5 of the video cable
connector(J201) and ground. I accessed ground by means of either the metal
collar around the connector or the copper tabs that are visible when the
expansion connector door is open. The expansion connector door is the
rectangular door on the right side of the console as seen from the front.
If either of these resistances do not read 0 ohms, then DO NOT CONTINUE.
I STRONGLY advise using a ohmmeter as opposed to a test light for these
measurements.
Parts required:
0. 1 5-pin DIN connector
1. 1 5-conductor cable
2. 2 RCA-type stereo plugs(my monitor used these)
Items 0 and 1 may be obtained together by removing the modulator from
your cable, though I didn't go this route. A surplus store(Advance Component
Electronics in Santa Clara, Calif.)was my source for these items. They had
TI modulators & cables, they just cut the modulator off of the cable and sold
them both side-by-side. I picked up a modulator to see how it connected to
the cable, and just plain curiosity.
0. I left Pin 1 unconnected since my monitor has its own power supply and
hence doesn't need +12V. This may help your console run a little bit
cooler since it doesn't need to power a modulator now.
1. I Connected Pin 3 and one of the GND pins on the DIN plug connector to
two of the wires in the cable. On the other end of the cable, I connected
the Pin 3 wire to the center wire and the GND wire to the shield of an
RCA-type stereo plug.
2. My cable had one shielded and three unshielded conductors, so I
connected the other GND pin to the shielding and the Video Out(Pin 5) to
the center wire. I then connected the center wire to the center wire of
another RCA-type stereo plug then connected the shields together.
Key slot
|
|
V
** **
******* | | *******
**** | | ****
** |___| ** Pin connections:
* *
* * 1. +12V
* * 2. GND(my console)
* O <-- Pin 3 Pin 1 --> O * 3. Sound Out
* * 4. GND(my console)
* * 5. Video Out
* * 6.(Collar) GND
* O <-- Pin 5 Pin 4 --> O *
* *
* *
* *
* O <-- Pin 2 *
** **
**** ****
******* *******
*******
I made up two of these things, tested them on my set-up, and gave one to
my supervisor, who reported that the cable worked pretty well. Also, taking
measurements on my console with an oscilloscope, I found the video output
level about 1 to 1 1/4 Volts peak to peak. This is included because the
video output voltage is nowhere in the manual, and I wanted to make sure
any monitor I bought would be compatible with it beforehand.
The best color combinations on a monochrome monitor are black, gray, and
white for foreground and background according to choice.
I almost forgot. TI and 99/4A is a trademark of Texas Instruments
Incorporated, RCA-type stereo plugs are(?) trademarks of Radio Corp. of
America, Advanced Component Electronics may be a trademark of Advanced
Component Electronics, and DIN may be a trademark of Germany(?) or Europe(?).
Deep Breath.
Kchula-Rrit