These Two Can Talk to Each Other!
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Why is This Such a Problem?
How to connect your TV to your video game console (Atari or otherwise) was discussed on Page 1, now we’ll look at how this situation came about. First, a brief overview. Then, if you’re interested, I go into the gory details of some of the history of consumer electronics, connectors, and video signals.
Here’s how it went:
TV’s had a pair of screw terminals to connect to an antenna.
Video games come out with a switchbox to connect to the antenna screws. They put out a video signal that simulates a broadcast TV signal.
The antenna connects to screws on the switchbox
The video game plugs in to the switchbox using the new and unusual RCA connector.
Cable TV appears. The cable that brings the signal in the house is a coaxial cable with an ‘F’ connector on the end. This goes into a cable box, and the cable box connects to the TV’s screw terminals in place of the antenna.
”Cable Ready” TVs appear, with an ‘F’ connector on the back that allows the cable box to be eliminated. Eventually, all TVs are “cable ready” and new ones don’t have screw terminals on the back any more.
VCRs become common consumer goods, and they use the RCA connector for a “composite” video signal. The composite signal is not the same as a broadcast TV signal, it’s a signal type that has only existed inside the television up until now in the ordinary consumer’s home. Since it doesn’t have the effects of being converted to a broadcast type signal and then back again, it’s a cleaner video signal. This is the same connector as the Atari, but with a different video signal!
TVs with composite inputs appear, using the RCA connector for the same composite signal as the VCR. If you plug your Atari into this connector, it won’t work because it’s a different type of TV signal. It’s not expecting an antenna-type signal.
The Gory Details
Once life with a TV was pretty simple. You had a TV, and an antenna to put signals into it. No VCRs, no cable boxes, no satellite dishes. Just an antenna and a TV.
Of course, that antenna only got you three or four channels, and you had no control over what was on your TV. But it was simple. So long as the reception was good, the wind didn’t blow over your antenna mast or spark plug noise from nearby vehicles didn’t wash out signals from the TV stations, reception was good and life was good.
Then came the first video game consoles. For the first time, the ordinary consumer had a way of putting something on their own TV.
There was only one way of putting a signal into a TV. First, the video signal needed to be converted to pretend to be an over-the-air TV broadcast signal. Then the signal was sent into the TV through the two screws on the back where the antenna hooked up:
Inputs on a TV from the 1970s.
Top, VHF Antenna.
Bottom right, UHF Antenna.
Bottom left, jumper for
internal coil antenna.
Above is a picture of a TV from the late 1970s. There are two sets of antenna screws, one pair for VHF (channels 2-13), one pair for UHF (the higher numbered channels) and a pair that act as a jumper to select an external or internal antenna. The internal antenna worked fine, so long as your favorite TV station had their transmitter tower in the middle of your living room.
Atari’s Video Connector
When Atari came out with the Pong, Super Pong, and Atari 2600 this was the only way they had to get the video signal into the TV set. Some video games used an antenna-style cable out of the console, known as a 300 ohm twinlead cable. This ended in two forked “spade lug” connectors. (Technically they’re “pressure terminal connectors”, but they’re typically called spade lugs, even though a spade lug is the proper name for a different connector.)
Atari, however, decided to use an RCA connector on the end of its cable, then have that connect to the TV through a switchbox. The switchbox had the twin lead connector on it.
The Atari 2600’s Video Cable
The RCA connector is commonly used for speaker cables and composite video cables today, but back then it didn’t have any common use in consumer electronics. Speaker cables back then had bare wire ends, and there were no consumer video cables. Pro video rigs of the time used BNC connectors and screw on connectors of different types, most commonly the type called “UHF connectors”.
Then came cable vision.
Cablevision’s Connector Choice
Cable television introduced a new connector to the consumer, the ‘F’
connector. It was suited for the coaxial cables that cable TV systems used to distribute their signals, as opposed to the flat twin lead cables commonly used on TV antennas. The ‘F’ connector later became a standard item on the backs of “cable-ready” TV’s.
If Atari had happened to use F connectors on their videogames, you could plug
them straight into the backs of current TVs. But F connectors are larger,
heavier, and more expensive than RCA connectors, so there wasn’t much reason
for Atari to use them. You could argue that the 7800 was released late
enough in the game that they should have had F connectors by then,
but you could also say that at that time the twin screw antenna connector
wasn’t dead yet, either, and that standard game/TV switchboxes all
had RCA connectors on them. So if the Atari 7800 had come out with an ‘F’ connector, it would have required its own unique switchbox. And since most TVs only had one ‘F’ connector, it couldn’t have shared that connector with the cablevision connection. So there was only one weak reason to put an F connector on the 7800, and lots of good reasons not to, at the time.
The Inputs of a “pro-sumer” TV set of the 1980s
The Atari Plan
Atari, and other companies of the time, wanted to make it simple to connect their electronics to the TV. This means that you don’t have to disconnect your antenna every time you wanted to play the video game, then reconnect the antenna every time you want to go back to watching television. They knew that if people had to do that, people would probably never disconnect their antenna, leaving the video game unused. That would not encourage further sales.
It’s worth noting that most households of the time did not have extra TVs sitting around. Most homes had only one television, and if there was a second TV it was used for watching TV. There weren’t any TVs hanging around waiting to be used as dedicated video game displays. A TV was too valuable as a TV for that, and there wasn’t room in the house to have a bunch of TV sets hanging around. Having a second TV set was a luxury.
So the switchbox allowed both the antenna and the video game to be hooked up at the same time. There were switchboxes with twin lead terminals (the pair of screws) on them as well. But the RCA connector is cleaner looking, and easier to connect and disconnect. No screwdriver (or kitchen knife) required.
You could hook up your antenna and video game at the same time by putting two sets of lugs under the screws at the same time. But this could cause interference or reduction in the TV signal, even when the video game was turned off. So it wasn’t the right way to do it, especially since TV reception was usually pretty flaky to begin with.
The Switchbox Solution
In the picture above, the twinlead that comes out of the switchbox connects to two screws on a transformer. Originally they were intended to connect to the screws on the back of a TV. But TVs don’t have screw terminals on them any more, now. The screw terminals have been replaced by the ‘F’ connector popularized by cablevision. There are two screws on the bottom of the switchbox. This is where the antenna wire that used to go straight to the TV would be connected. The connector on the top is an RCA connector, this is where the video game connected.
Because the Atari uses a different connection than the antenna, you can’t mix up the two connections. That means when you put the switch on the “Computer” side (also printed as “Game” on some switchboxes), you’ll get the videogame, and when you put it on TV you get the antenna, not vice-versa.
A Collection of Matching Transformers for TVs
When the connector on the back of the TV changed from a pair of screws to an ‘F’ connector, it wasn’t just the type of connector that changed. Otherwise it would be possible to simply strip the ends of our twinlead antenna wires off, stick one in the center hole of the ‘F’ connector and tape the other one to the outside barrel.
This wouldn’t give a good signal because the impedance of the signal changed as well. I’m not going to go into the electrical theory behind impedence here. Let’s just say that the change from a flat twin lead wire to a coaxial wire will cause a lot of the signal to be lost unless you use a special component called a matching transformer. The matching transformer lets the signal go smoothly from one type of wire to another.
Since we’re getting our videogame console’s signal out of the switchbox in a flat pair cable, and we need to put it into a coaxial ‘F’ connector, we need one of these (unless we use “Method 2” from Page 1).
Matching transformers, by the way, were something of “black magic” to most people back in the 1970s and early 80s. They didn’t know what it did, or what was in it. They didn’t know that it’s a component that doesn’t burn out or age appreciably. Cable TV technicians took advantage of this ignorance. When they made a service call where someone was complaining about bad reception, if they couldn’t find any other obvious problem they’d replace the transformer to make a show of doing a “repair”. I managed to build up a fair collection of transformers by asking people for the “bad” transformers that the service technicians left behind.
Once people found out I knew something about TVs, they’d often call me when they had problems. Especially since a cable service tech wasn’t going to be around until after the show they wanted to watch now. I would replace their transformer, too, telling them it was one that I had “repaired.” Though I would also do some other troubleshooting, looking for bad or oxidized connections, damaged cables, connectors exposed to weather, and so on. Then I’d show the person what the actual problem was, so that they could direct the cable tech to get the proper repair done when they arrived.
Since I had replaced the transformer, they would know that it wasn’t the problem and wouldn’t let the cable tech get away with replacing it and claiming to be done. To be honest, I did actually do some work on the transformers. I would clean oxidation off the contacts and I used a tool I had made to push the internal contacts back into shape if they’d been bent so as to not contact the center conductor properly.
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