Hello and welcome to another episode of the 8-Bit Guy.
Today, I’m going to be attempting to modify this Atari 7800.
Now, for those who are unfamiliar with the console, let me tell you a little bit about
it.
So this is the 7800, mine is not in perfect condition, unfortunately.
But that also means it is a good system to mod since I don’t need to worry about keeping
it in original condition.
In fact, that’s why I don’t want to mod my 2600.
This is the power supply.
I usually label mine so I don’t get them mixed up.
I also keep the wires rolled up like this to keep the wires from getting kinks in them.
On the front you have two joystick ports.
And next to those you have two unmarked switches.
These are actually the difficulty level switches.
On the rear, you have that funky power connector, The RF output jack, and here’s another crazy
thing.. a switch that selects between square or circle.
Apparently this is to select channel 3 or 4 as your transmit channel on the RF port.
So, one of the things that makes this console so interesting is that it can play all of
your old 2600 games like Space Invaders, Yars’ Revenge, and Missile Command.
But it can also play its own, more advanced games.
This is the only 7800 specific game I have in my collection right now.
The cartridges do look more or less identical, which makes sense being the slot has to be
able to accept both kinds.
So let’s hook this thing up and see how it works.
So we’ve got the power connector in..
Next the video cable, and finally a joystick.
I should mention that the Atari 7800 has its own special joysticks, which I don’t currently
have.
But it can also work with standard 2600 or Commodore joysticks as well, but some 7800
specific games require the second button.
So, you might think you could just plug this straight into your TV or monitor’s video
input jack.
But that won’t work.
This is an RF signal, and besides where would the audio come from?
So, you’ll need an adapter such as one of these old switch boxes.
And in my case, I need another adapter for the F-type connector since my TV is from the
1990s.
So, these things are a pain in the butt, and honestly, it’s the reason I’ve never bothered
to collect any other Atari 7800 games or peripherals.
In fact, I’m really surprised that Atari didn’t put a composite video connector on
the machine.
I mean, when the 2600 came out in the late seventies, really, pretty much no TVs had
composite on them, but by 1986 or 87 when the Atari 7800 was coming onto the market,
a lot of TVs did have those, plus there were computer monitors and other things, so I really
don’t understand why it doesn’t have composite on there.
So I bought one of these composite video conversion kits from ebay for around $10.
I’m going to find out how hard it is to install this, and hopefully it will make it
look better!
So, this mod will improve the output of both the picture and the sound.
However, I think the most important benefit that this mod gives is simply the ability
to connect it to more modern televisions and monitors without having to worry about finding
something with an, you know, analog RF interface.
So, here are all of the parts that came with the kit.
It really isn’t a lot, actually.
So I suppose the first thing I should do is assemble it.
I’ll just bend the leads on this transistor like this, and poke it down in the holes.
Then I’ll solder it in place.
And, of course, trim the excess leads off.
That was simple enough, now onto these two resistors.
I’ll just bend the leads here and poke them down in the correct holes.
Then I’ll solder them in place.
And this part is all finished.
So, now it’s time to open up the 7800 and take a look inside.
There are 5 screws on the bottom, which I’ll take out fist, and it opens right up.
OK, so this shield has to be removed.
There are these little twist tabs that will need to be straightened out with needle nose
pliers.
Then, in theory, it should lift off.
However, mine was extremely stubborn, almost like it was glued down.
I realized I could still pull the board out, even with this shield on.
And, I eventually managed to work the shield loose.
Looking at this bottom plate, you can see some significant corrosion going on here,
and it looks like it started there, leaked its way over, and worked its way down.
And I’ve come to the conclusion that this was exposed to some water.
It probably went in here, and it came through right there in that hole for the cartridge
port.
And that’s why there’s.
That’s why there’s some corrosion on the board there and over here.
However, it seems to still work.
You can also see a lot of the corrosion down inside the plastic case.
So, I’m going to wash that out before we re-assemble it.
Lots of people joke these days that they want to see vinegar in every episode.. well, here
you go.
I’ll scrub some of this on here and come back and check on it later.
So let’s take a closer look at this board.
Over here we have the Maria chip, which gives the 7800 it’s enhanced graphics capabilities.
Over here we have 4 KB of static RAM, followed by 4KB of system ROM.
So there’s essentially 8K on board, and another 48K can go in the cartridge slot.
So this is the 6502 compatible CPU, although Atari calls it the Sally chip.
Keep in mind this is more or less the same CPU that runs the Commodore computers, Apple
IIe, Nintendo, and pretty much all of the Atari line of 8-bit systems.
Over here we have the TIA chip.
This known as the television interface adapter.
It’s the exact same chip used in the Atari 2600 to give it video graphics and sound.
It’s here for backwards compatibility with 2600 games.
However, it is also the sole source of sound on this machine, unless your cartridge has
its own sound chip.
This was a sore point on this particular console.
And last is the RIOT chip, which is just an input output controller for the joysticks
and other things.
OK.
So I just took this thing out and rinsed it with the garden hose and it looks a lot better.
The bottom RF shield looks much improved.
I can at least say the corrosion is neutralized so it won’t continue.
According to the included documentation, I’m supposed to literally just cut out these two
resistors as they won’t be needed anymore.
So I’ll go ahead and do that.
At first I thought maybe I should desolder them because I figured I’d be attaching
wires here.
But nope, they are just going away for good.
So the easiest thing to do is to just to cut them out.
They also want these 4 wires removed and the official documentation actually says I should
break the entire little board off of the RF modulator.
But I do not like that approach for two reasons.
One is because it makes this process irreversible.
If the mod doesn’t work out, I want to be able to put things back the way they go.
Number two is because you know, if the RF modulator is not going to work anymore, I
don’t want to have the jack back there.
It might confuse somebody, maybe even myself later if I forgot the jack doesn’t work.
So I decided to just remove the modulator completely.
I don’t have any fancy desoldering equipment, so I just used solder-wick, or some people
call it desoldering braid.
Either way, it is cheap and it works.
So I was able to remove the modulator.
OK, so I thought I would turn my attention to the case plastics.
I need to drill 3 holes, so I usually put down some masking tape, which makes it easier
to mark on it where I need the holes to go.
I am spacing them a half-inch apart.
And the holes will go at the intersection of these marks.
This plastic is very brittle, so I will be starting with a small bit and working my way
up to a larger one.
Some people ask why I don’t just use a special step drill bit.
Well, it’s because I don’t have one and most people probably don’t either.
Plus they are expensive.
And this process works just as well for occasional use.
OK, so I’ll do a test fit of the RCA jacks.
Looking good!
Next, I’ll strip these wires.
Then I’m going to bend the edges of these grounding connectors to make them easier to
solder to.
I’m just going to run these over the wire like this.
The reason for this is that all 3 jacks will share the same ground.
So I’ve soldered this one on.
And I’ll solder the other two once I attach them to the jacks.
OK, the common ground wire is finished.
I should point out by the way that this kit came with 3 jacks, one for video and two for
audio.
However, this console does not produce stereo sound.
So really, the two audio jacks put out exactly the same thing.
In fact, I thought about just eliminating one of the jacks and just putting one audio
and one video jack on the console.
OK, so all that’s left to do now is to solder the wires to the main board where the RF modulator
used to go.
I’m just going to go ahead and do a test of the system just like it is before I bother
to re-assemble it.
And, it works! first try!
So, I captured some video from this thing using the RF output before making the modification.
And I wanted to be able to show some comparisons with how it looks now.
So this is Missile Command, and now let’s take a look at it on composite.
The image is noticeably cleaner.
Let’s take a look at Space Invaders.
The sold background really shows off the interference on RF.
And now here’s the composite version.
OK, so Yars’ Revenge revealed something odd.
Pay close attention to the background sound on this game.
Now listen from composite.
It sounds different.
I think the signal is too hot for my capture device.
However, I’m not going to worry about it because it still sounds fine when played on
my TV.
Speaking of sound..
Here’s Ballblazer on RF.
Wow, there’s such a huge difference in graphics when you move to an actual 7800 game.
And, of course, it will look even better when I show you the composite version.
And it does.
However, on the composite version it actually has no sound at all.
So, Ballblazer is one of only 2 cartridges that contains its own sound chip.
It turns out this mod doesn’t support these sound chips the way I’ve done it.
However, it is possible to fix this by the addition of one extra wire.
So that’s what I’m going to do next, since I do actually own one of these games.
OK, since this switch is technically no longer needed anymore and it’s in the way if where
I am wanting to solder, I’m just going to go ahead and desolder that.
Again, I’m just going to use some solder wick to remove the switch, then I’m going
to need to remove a small capacitor.
OK, so the switch is done, and I’ve already removed the solder for this capacitor, so
I’m just going to pull it out of there.
OK, so the extra sound wire for the cartridge pokey audio chip goes here.
OK, so the instructions with this kit said to throw away the RF shield, but I am unwilling
to do that, so I’m going to put it back on.
But I did run into one problem which has nothing to do with the shield.
The board will not fit back in the machine due to this wire, and there’s really not
anywhere I can see to run the wire.
So I’ve decided to make another modification.
I’m going to cut off this small section of the shield, along with a corresponding
piece of the logic board.
This is a pretty small area of the board and doesn’t even have any traces on it, so it
shouldn’t hurt anything.
And, it does seem to fit perfectly now.
Now to just figure out where to mount that tiny little board that I added.
It came with this little piece of double-sided tape, however, my experience is that double-sided
tape lasts maybe a year or two at best and then it always falls off, so I decided not
to use this.
Instead I’m going to use this zip tie through the holes that used to hold down the RF modulator,
and that will hold the little board in a perfectly benign place without any problems.
Now I’m just going to put the cover back on and screw it back together.
So here’s the finished product.
And I’ll take an opportunity to try out Ballblazer again after the last modification.
And it does seem to be working just fine.
OK, so this mod certainly turned out very well.
This is a mod that is inexpensive, and definitely one that I would recommend doing.
In fact, I might actually consider buying some more native Atari 7800 games to play
on this console now, as well as getting the proper controllers for it.
But anyway, I may even look into modifying some of my other Atari systems as well.
Anyway, I have three quick announcements that I need to make.
The first thing I want to tell you about is the game I’ve been programming for the Commodore
64.
It’s a real-time strategy game, only the interface has been simplified so that it can
be played with a keyboard and joystick instead of a mouse.
I’ve sort of adopted the look of the Ultima games, with a bit of Sim City thrown in too.
I think it’s going to be a really fun game to play and I will be launching a Kickstarter
for it very soon, because I want to make this a fully boxed commercial release.
I have a page on my website for updates on this game, so check there for more information.
Also, I wanted to let you know that I will be at the Long Island Retro Gaming Expo this
August, again check the description field for more info.
Last year I went to a similar expo in Portland and talked to a great group of people, signed
some interesting artifacts for people, and I met a lot of really cool people, and generally
had a great time.
So I hope to see some of you there!
And the last announcement I need to make is that I’ve been invited to be part of the
upcoming documentary called “The Commodore Story,” which is currently in a Kickstarter
phase.
Check that out, there is more detail in the description field.
Well, if you made it this far, then thanks for watching, and as always stick around and
keep checking back regularly for more content!