This VGA Adapter for Atari Hard Drivin’/Race Drivin’ Cockpit also provides for delaying horizontal and vertical sync in order to center the picture on those TVs and monitors that need it.

 

When I decided to make a video of my Atari Race Drivin’ cockpit game I discovered that there wasn’t room for the camcorder and still be able to play the game. I made an adapter on a perf board to connect the game to a VGA display.

 

My Vizio VA19L worked! Other TVs didn’t. None of my computer monitors would sync to the game.

 

Horizontal Sync for the Cockpit (Main Board) is 25 KHz, Vertical Sync is 60 Hz. NTSC Horizontal Sync is 15.734 KHz and Vertical Sync is 59.94 Hz. The slowest VGA Mode is 31.778 KHz Horizontal and 60 Hz Vertical (for 640 x 480 x 16 colors) and 31.778 KHz Horizontal and 70 Hz Vertical (for 640 x 480 x 256 colors). That is probably why the Vizio (with a VGA input) worked and the computer monitors did not.

 

Computer Monitors only have to work down to 31.778 KHz. So far I have only found one that would sync to 25 KHz.

 

In the Winter of 2018 when I decided to sell the game I made a PC Board for it. For my first VGA board I spent some time to get the pinouts of the VGA connector right. I got them wrong anyway.

 

Then I tried it on a Samsung T22C350ND. It synced up ok but the horizontal centering did not have enough range. I designed a circuit to delay the horizontal sync so I could center the picture. I made a PC Board for that too.

 

Then I realized that the vertical centering also needed help. More circuitry and another PC Board. This is the one I am posting since there is a switch (SW1) to select either the normal sync from the game or the delayed version with an adjustable delay. 

 

It worked great with my Samsung T22C350ND and really great on my Magnavox 40” LED 40ME324V/F7. Imagine Hard Drivin’/Race Drivin’ on a 40” display. Of course it won’t be HD but if you use an HD camcorder your videos should be better than the ones I made with my Flip Camera.

 

The adapter requires +5V but the test blades along the top on the Main Board provide +5V, GND, R, G, B, /CSYNC. The test blades are not Fastons. I connect to them with alligator clips.

 

To mount the VGA board I attached a short 1 x 2 to the side of the cabinet with white glue. I also used two screws that were short enough so they didn’t poke through the side. The screws probably aren’t necessary. The VGA board is attached to a piece of tempered hardboard (Masonite). The tempered hardboard is attached to the 1 x 2 with two #6-32 x 1" hanger bolts so I could easily remove the VGA board for shipping. A hanger bolt is a screw where half of it is a wood screw and the other half is a machine screw.

 

To use the delayed sync:

 

1. Trimpot R13 controls the width of Horizontal Sync. Adjust it to produce a 4us pulse.

 

2. Trimpot R12x controls the delay of Horizontal Sync and therefore horizontal centering.

 

3. VGA displays don’t like having the leading edge of Vertical Sync delayed so turn Trimpot R15 fully counterclockwise.

 

4. Trimpot R17 controls the width of Vertical Sync. VGA displays don’t seem to mind the width of Vertical Sync. It starts displaying the lines after the trailing edge so R17 controls vertical centering.  

 

5. You need a small slotted screwdriver with a 2mm tip to adjust the trimpots. On eBay do a search for Screwdriver 2mm Slot. Or make your own by grinding down a metal rod.

 

And now some notes.

 

1. The VGA connector is an HD15 connector. It should not be confused with a DB15 or DB9 connector. The HD15 has three rows of contacts. The DB9 connector has the same size shell but only two rows of contacts.

 

I bought my HD15 connectors at Jameco but they no longer sell it.

 

In finding another source I found that most companies wrongly call it a DB15 connector. In order to get the right part you search for “VGA Connector PCB” and then look very closely at the picture. I found some on Amazon, sold by uxcell. I got 10 for $8.72.

 

           uxcell 10Pcs DB 15 Pin 3 Row Female D-SUB VGA Connector PCB Mounting Right Angle

 

You can find the part on eBay with costs and delivery times that vary widely.

 

I recommend you make sure you can get the connectors before you order boards.

 

2. The 75 Ohm parallel resistors might not be needed. It depends on whether you have both your VGA monitor and the game monitor connected together. Play with it to get the video levels that you need.

 

3. You will need a VGA cable to go from the Adapter Board to the display.

 

 

These are the videos I made of my games: Star Wars, TomCat, and Race Drivin’ : www.jmargolin.com/videos

 

In December 2018 I sold the games to the Strong Museum of Play in Rochester, NY.  https://www.museumofplay.org/

 

I have posted much more information on Hard Drivin’ and Race Drivin’ at www.jmargolin.com/schem/schems.htm

 

I was the project engineer (and hardware engineer) on the games and now (36 years after Atari Star Wars was produced and 31 years after Hard Drivin’ hit the arcades) I am finally done with them.

 

If you are not already a Maker (and you want to be one) see my tutorial on Making Things at

www.jmargolin.com/making/jm_making.htm


JM


May 26,2019
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