Converting Apollo Monitors

We have only tested these ideas with LINUX running XFree86

The inspiration for these conversions came from Russell Ayling's Apollo FAQ - monitors info. If you have one of these monitors, check the above document to determine which type you have. To make them work with Xfree86 and svgatext, build the conversion circuit, shown below. Be careful that you get the pinout right for the vga connector.

Relevant VGA pins
+-------+---------------+
|signal	|	pin#	|
|-------+---------------|
| HSYNC	|	13	|
| VSYNC	|	14	|
| R+	|	1	|
| G+	|	2	|
| B+	|	3	|
| R-	|	6	|
| G-	|	7	|
| B-	|	8	|
| Gnd	|	10	|
| Cl Gnd|	11	|
+-------+---------------+
The circuit

The circuit can be powered either by the PC or the monitor (if you are brave), the yellow wire on PC internal power connectors is 12V, the red wire is 5V. If you use 5V you will not need the voltage regulator. Make sure that all unused input pins on CMOS ICs are grounded.

To test: Start up X, and open a few windows, if the windows are "broken" twiddle the little sync adjust trim-pot until the image on the screen is stable.

How it works

Normally the green signal is biased positively by the voltage divider formed by the 1K potentiometer, since the analog switch IC1 (4066) is conducting. The gates are paralleled to reduce impedance, thus increasing the bias. When a sync occurs the switch is turned of, and the green line is dropped, creating a (relatively) negative sync signal.

XFree Settings

1024x800 15" and 19" monitors.
	ModeLine "apollo" 65 1024 1120 1160 1344 776 780 788 824

1280x1024 19" monitors 

(Southern Hemisphere)
	ModeLine "Apollo" 125 1280 1312 1504 1696  1024 1027 1030 1080

(Northern Hemisphere, running in Canberra mind you)
    	ModeLine "Apollo" 125 1320 1400 1504 1664  1024 1027 1030 1080

note you may have to make adjustments to these
Disclaimer: The author, the Australian National University, and the Research School of Biological Sciences are not liable for any injury or damage caused by the use of these ideas, use them at your own risk.

Comments and suggestions?, Javaan.Chahl@anu.edu.au

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