My "custom" Supercharger modification

[highinfidelity]

Hello there folks! It took me more than two years to finally decide it was time to put my hands on the good old supercharger (not exactly an "executive officer", huh? ) but now it's finally done.

 

I decided I wanted to make something different in order to 1) complicate my life 2) avoid having a pin-cut I.C. glued on the back side of the P.C.B. 3) have a reminder of the normal/modified mode as I knew that I could never remember in which position of the switch the modification was operating.

 

The quad OR I.C. has been fit between previously existing I.C.s - there's just as much room as you need to do so - in a place where the need for cutting and restoring P.C.B.'s copper tracks is minimized. As only one OR gate is used, I wonder if there are smaller I.C.s available (ex: a dual OR) to make things easier, but as I had no time to go through I.C. codes I let this chance go and leave it to people more confident with I.C.s. Back to topic, the quad OR is mounted over its appropriate socket, as thickness is not a problem on the central area of the P.C.B. and sockets totally eliminate any heat issues when soldering, which is very convenient.

 

P.C.B has been perforated with a precision microdrill. You can see I haven't been as much precise as the microdrill as there is a full line of holes I made in the wrong position at first try (damn...!). The socket is then kept in place directly by soldering points on the bottom side of the P.C.B. Cutting a portion of the ground track and rewire it with a short piece of cable has proven to be necessary. Existing tracks had been cut or deleted where necessary with a diamond bit.

 

A dual colour (red/green) L.E.D. has been added as a "reminder" (green = modification activated, red = standard operation mode). This requires the use of a dual two positions switch, which complicates wiring a bit. C.C. power supply is taken directly by the board and sent to the L.E.D through a 470 Ohm resistor (barely visible under the switch cables). The L.E.D. is as well kept in place only by soldering points on the other side of the P.C.B..

 

Sorry if I have been picky but it took me some patience to do this, and I guess that if I tried to discuss it with my girlfriend I'd be single again before this evening

 

Cheers!

 

Edited November 27, 2007 by highinfidelity

[Rybags]

But what does it do? Let you play bank-select cart images or something?

[highinfidelity]

Funny that you've been the first to reply, as the supercharger you see actually came all the way north from... Australia!!!

 

Honestly speaking, I have never heard mentioning a supercharger before subscribing AA, and as I recall even Sir Thomas Jentsch never did, I guess it was not available in our countries altogether...

 

You can read a complete answer to your question here:

 

http://www.atariage.com/forums/index.php?showtopic=41528

 

As a side note, some fellow there pretends the I.C. is "very rare with few leftovers at Radio Shack". Instead, it's an ultra-common quad OR gate you can find almost everywhere.

Edited November 27, 2007 by highinfidelity

[+batari]

Nice looking mod, probably the cleanest I've seen!

 

I notice that the mod uses a whole quad-OR IC but only really needs one gate. A single OR gate can be effected by two diodes and a resistor, as shown in ASCII:

I1 -->|--+--- Out
	 |
I2 -->|--+
	 |
	 \
	 / 100k
	 \
	 |
   GND

Seems like it might be easier to fudge these on there than an entire IC.

[shadow460]

*gears are turning*

 

I had trouble finding a 7404 a while back. This is Oklahoma City where sometimes people are a bit backward about that stuff. If I built my own OR gate, though, I know exactly where I can get parts for that.

I know there's a FAQ somewhere on how to mod the Supercharger, but I must have overlooked it while browsing back through the hardware section.

[CPUWIZ]

*gears are turning*

 

I had trouble finding a 7404 a while back. This is Oklahoma City where sometimes people are a bit backward about that stuff. If I built my own OR gate, though, I know exactly where I can get parts for that.

I know there's a FAQ somewhere on how to mod the Supercharger, but I must have overlooked it while browsing back through the hardware section.

 

Just thought I'd mention that the 7404's are hex inverters and not OR gates.

 

E.G.

 

04:

 

IN 0 = OUT 1

IN 1 = OUT 0

 

32:

 

OUT = IN1 | IN2

[shadow460]

Ah, my bad. I got my numbers mixed up.

Edited November 29, 2007 by shadow460

[highinfidelity]

Nice looking mod, probably the cleanest I've seen!

 

A single OR gate can be effected by two diodes and a resistor, as shown in ASCII:

Thanks a lot, I appreciate it! These works are pretty easy, in the end, but they take a lot of time and patience.

 

Yes, that is correct, but DDL (diode-diode logic) has obvious drawbacks with fan-out and, as long as this was the only supercharger I had and didn't want to mess it up, I refrained from experimenting so much. It MAY work, though, and yes it would be much easier to fit three discrete components on the board as they could be placed almost everywhere. The wiring would be easier too as they don't need power supply.

 

If you're going to experiment this solution, please keep me updated, I'm curious.

[shadow460]

If I can dig up a schematic for the mod, I may try it myself. I'm not a hardware expert, but I've done a few things. That might be a good tomorrow project one I get back from the battery shop (just fried a set with an experiment...killing batteries is not fun...)

[+remowilliams]

Yeah, that's a lot cleaner looking then my SC mod.

 

If I can dig up a schematic for the mod, I may try it myself.

http://members.cox.net/rcolbert/sc.htm

[shadow460]

Nice looking mod, probably the cleanest I've seen!

 

A single OR gate can be effected by two diodes and a resistor, as shown in ASCII:

Thanks a lot, I appreciate it! These works are pretty easy, in the end, but they take a lot of time and patience.

 

Yes, that is correct, but DDL (diode-diode logic) has obvious drawbacks with fan-out and, as long as this was the only supercharger I had and didn't want to mess it up, I refrained from experimenting so much. It MAY work, though, and yes it would be much easier to fit three discrete components on the board as they could be placed almost everywhere. The wiring would be easier too as they don't need power supply.

 

If you're going to experiment this solution, please keep me updated, I'm curious.

 

Well, I busted out the Starpath supercharger I'd won on ebay a couple of years ago and got busy. I tried the diode-diode logic and it gives me rolling colors on the screen. It does that no matter what position the switch is in.

When this Supercharger was built, whoever built it skeleton wired some components on the board. I did the same thing with the 1N914 diodes and the 100K resistor.

Nothing's shorted, and I double checked the wiring. I did hook to a different ground that what's shown in Bob Colbert's diagram. All three of the discrete components are placed on top of the board just like the ones the Supercharger was built with.

 

I brain farted at first and didn't cut the trace in Colbert's diagram. I powered up the Supercharger and it worked just like it was supposed to with a multi load game. I went back and snipped the trace and that's when the rolling colors began.

 

The Supercharger is still functional after I reconnected the trace under the board. You can see the reconnection in the second picture. I'm not worried about it much, save for the audio line mod I did a couple years back. In the meantime, I'll have to con someone out of a 7432 as Radio Shack doesn't carry them anymore and there's no local supplier.

 

lol, when I was taking these pictures, I pulled the SC's audio plug out of the headphone jack on my computer speakers. I forgot to turn the volume down from max, though, and my webcam program clicks when you take pictures...

 

CLICK!

 

I must have jumped about three feet in the air!

 

A quick rundown of what you're seeing here: The wires over the top of the custom chip are hooked to some things that were skeleton wired in when I got the Supercharger. The wires you see running across the top are what I hooked in this evening. You can barely see the 1N914 diodes I used. The black ends are wired together with one end of the 100K resistor. the resistor is grounded to the ground leg on the middle RAM chip in the photo.

 

Wait a minute...did Colbert cut a trace from the ROM IC or that last RAM IC? What I cut the trace from is actually a RAM IC. I left the Starpath ROM untouched. This is definitely how Colbert's diagram shows, but was his diagram made with an earlier model Supercharger?

Edited December 18, 2007 by shadow460

[+batari]

You might try a smaller resistor. You should measure the voltage at the output - it should usually be 0v I think (not 100% sure on that), and if it's not close to that, the 100k might not be strong enough to pull the voltage down. If you have the parts lying around, try 50k, 20k, 10k, or 5k, but don't go too small. If you need less than that, you probably want to get the 7432. (And thanks for testing my idea, regardless )

 

EDIT: corrections made.

Edited December 18, 2007 by batari

[shadow460]

I'll grab one of those multi packs from Rat Shack tomorrow and give it a try. The parts came in bundles anyway, so I've got like a billion of the 1N914's and the resistors. I can parallel some resistors to find an approximate value and get the right size when I find it.

 

Is there anything I missed in the actual workmanship that anyone's seen?

 

If it's possible to get this working, I'll do it. That'll make it just that much easier to mod the SC for those who don't care much for mail ordering parts or chasing their local suppliers (Synergy ) down.

 

Another thing I thought of was using LEDs for the logic diodes. I was looking at the forward bias voltages, though, and I'm not sure if having a diode that needs 2.8 volts for forward bias would be a good idea. IIRC, the ones I used have a 1.7v forward bias rating.

The LEDs might not be visible for long, but it would add a cool effect to the Supercharger. I assume one might be able to see them flicker as the thing works.

 

EDIT: I wired all five of the resistors in the pack parallel, knowing how this would affect the value. 1/100K * 5 = 1/20K, so the resistance is 20K. The voltage at the output is about 2.5 now, and the SC loads Escape From the Mindmaster just fine. With the switch in the ground position, Escape crashes instantly when it goes from title screen to the first maze. With the switch in the other position, Escape runs fine through at least Maze 3, where I got bored playing. Escape player know that Maze 3 is in the second load, so the unit is multi-loading just fine. I'll test it in earnest later when I try to increase the world record on Escape even further.

 

Now on to Pac-Man and Demon Attack...

 

Pac-Man works. In the normal mode, it crashes as soon as you try to start the game. In the modified mode, it seems to play just fine.

 

I think it's just a matter of getting the right resistor value at R1, probably 5K or something. 20K seems to work, but it leaves the voltage at Y1 around 2.5 volts. Bottom line, though, is that it's indeed possible to do this with discreet components, and those are more likely to be in the parts bin than a 7432 IC.

 

If anyone's following the pictures I posted, the only differences are that the resistor value needs changed and the wire is not needed on the bottom of the board. Everything's still skeleton wired like the other stuff that Starpath built in.

Edited December 18, 2007 by shadow460

[shadow460]

Oh, what the heck...here's a detailed description of how I did it:

 

Here I present The Complete Idiot's Guide to Modifying The Supercharger

 

First, we need to know which pin is #1 on each of the IC's, and how they other pins are numbered. I'm going to treat the row of components on the one side of the board as an IC for numbering purposes. I'm also going to explain a simple mod to the audio line to make it easier on modern music devices and I'm going to add everything on top of the board instead of the bottom. I'm also going to assume you either have actual Starpath tapes and a stereo tape recorder like I do or that you have the mp3 files on your digital player. I'm going to assume that you have a program such as playbin that can turn .bin files into audio the Supercharger can load, and I'm going to assume you have at least one Starpath game in mp3 format on your computer.

 

The parts:

One resistor, 5K to 20K at 1/4 watt should work.

Two switching diodes, 1N914 is common and is what I used.

The smallest SPDT switch you can find. It'll have two positions at the lever, and three pins.

About a foot each of three or four colors of wire, I used red, white, green, and black.

One 1/8 inch replacement stereo headphone jack.

Rosin core solder, probably about three feet if you use a lot.

Elmer's School Glue stick

 

Tools:

15 watt soldering iron, grounded if possible.

Desoldering tool (recommended, but not required)

Straight blade screwdriver

Xacto knife

Wire strippers

#1 point Phillips screwdriver

Hacksaw

Hair dryer

Multimeter (known as a Fluke hereafter)

 

Case mod:

 

Use the hair dryer to heat the Supercharger's main label up. Gently begin peeling at one corner, heating as necessary to loosen the glue. Alternately, you can cut through the label with the Phillips screwdriver, but this will scar your Supercharger's label. Once the screw is exposed, you can leave the label as is and remove the screw. Working from the connector end of the cart, gently pry the halves apart. The cart will hinge open on the end label, so be careful not to tear the end label in half.

Remove the board and the audio wire, then reassemble the cart without them. Tighten the screw. Look at the end label, and look down the sides. You'll see a hole for the audio wire. We want another hole on the other side for the toggle switch. The plastic is not too tough, so your #1 Phillips will cut right through it. Note that there is a split between the case halves where you need to make the hole, so you have to squeeze them together a bit while you cut the hole out.

 

Now let's get an overview of the board. Hold the board with the component side facing you and the edge connector pointed down. Four IC's should be on the left. The top is the ROM IC, or U1. The next three are RAM, and for this guide we're going to number them from the top down, U2, U3, and U4. The largest IC is the custom Arcadia chip, which we'll call U5. LAst is the row of components which we will fudge and refer to as U6. U7 would refer to the 7432 in a modified Supercharger, but that's not present or we wouldn't need this guide.

Time for more physical mods. Make a square cut on the top left side of the board. It should extend down almost all the way to U1's legs, and it should be about that same distance across from left to right. In other words, make it square using U1 as a guide. My Supercharger had no traces in that area, but check yours anyway and if they are there, cut around them.

Next, let's knock out the simple mod first--the audio line. Cut the audio wire as close to the plug as possible, then strip about half an inch off the conductors. Grab that stereo jack you have and hook the white wire to BOTH of the connections inside the jack. The other wire is ground, so solder it to the largest connector. Make sure the ground and the other wires don't touch, then use the Fluke to ensure that the ground wire has continuity from the SC board all the way to the largest ring on the jack. The white wire should have continuity from the SC board to BOTH the middle ring and the jack's tip. If so, assemble the jack and that's done.

Another solution to this is to permanently mount a 1/8 inch mono male to 1/8 inch stereo female adapter onto the existing jack. That's what I did, then I taped the jack on with electrical tape and glued that down so it would not unwind.

 

Why mod the audio line anyway, you ask? Simple. Back in the day, shoebox recorders were common. That's whaty ou see pictured in the Arcadia manuals with the Atari--a shoebox recorder. Those old recorders have a monaural output.

On the other hand, today's portable CD players, tape players, ipods, mp3 players, etc, have a stereo output. The Supercharger was not designed to be used with these new devices, and plugging it into them results in the left channel only being fed into the supercharger, while the right channel is shorted to ground. This can strain the audio circuit inside your player (or whatever it's hooked to), resulting in premature failure of the right channel audio. I'm not saying it will damage your ipod or whatever, just that it could. It can also cause problems when loading games into the supercharger, as essentially only half of the signal gets through from the ipod (remember that an old shoebox recorder is going to route the whole signal to only one channel, the ipod routes it to two).

 

Now for the more fun mod:

 

A few posts up, Batari has a simple diagram which is the actual bankswitching mod itself. In his diagram is an OR gate. If you look at the pinout of a 7432, you see that each of the OR gates on that IC has two inputs, Ax and Bx, and one output, Yx. Let's consider just the first gate, then, which has inputs A1 and B1, and output Y1. The 7432 has a ground leg, which we will also recreate, and a power leg which we do not need.

Take your two diodes and note which end has the stripe. If you set the fluke to the diode check you can hook the diode up so that the black fluke lead is hooked to the striped end lead on the diode, and the red lead to the other end. You'll see some numbers on the fluke. If you hook the fluke leads up the other way, it will show an OL or some other odd message instead of numbers. This tells you which lead on the diode is anode--when the numbers show, the red fluke lead is on the anode. The striped end of the diode is cathode, and that's where the black fluke lead would be when you have numbers on the LCD screen.

take the two diodes and twist their cathode leads together. The resistor does not have anode and cathode, so just pick a lead and warp it around the cathode leads. Leave about 1/4 inch of the resistor lead untwisted. Solder the whole thing together save for that last 1/4 inch. Trim the diode leads but leave the resistor lead alone.

 

Now look again at the SC board. Each of the IC's has a notch EXCEPT for U6 (that's the component bank). With the notch pointed UP, the top left pin is pin 1. The pins are numbered down the left side, then back up the right side. The memory chips U1 to U4 all have 24 pins, so the top right pin is pin 24. On the left side, ging from notched end to other end you have pin 1 to pin 12, then going from other end to notched end you have pin 13 to 24. REMEMBER THIS. As for the component bank at U6, we're going to assume U6 is oriented the same way as the custom IC, U5.

 

Hook one of the anode leads from your OR gate (that's the diodes and resistor circuit you made) to pin 7 on U4. It's the seventh pin down on the left of the chip. Flip the board over and cut the trace on THAT side of the board that leads from pin 7 of U4 to pin 35 of U5. pin 35 is sixth up from the bottom on the left side of U5 as you held the board earlier. Check it for yourself and see, though.

See that conglomerate of wires with the cathode leads? Tin the 1/4 inch lead that you left on the resistor, then solder it to pin 35 on U5. Ensure that the three leads you soldered together are still, in fact, together.

Next, solder the other lead of the resistor to pin 12 on U3. This is where the ground connection from batari's diagram is made on the SC board.

Cut the other anode lead to a length of about half an inch. Position the OR gate above U3. You're done with the board for now.

 

Now take the switch and hook about six inches of three colored wires to it. I hooked red to the center lead, then I flipped the switch body so it's perpendicular to the board. I hooked black to the top lead and green to the bottom.

While you're at it, let's prepare the switch to be mounted in the SC case. It should have a large flat washer and a smaller star washer. Remove all the hardware from the switch body, then place the flat washer on followed by the star washer and one of the nuts. Leave the nut loose until you have the wires connected to the switch.

Once the wires are connected, lay the switch and the SC board back into the case. Cut the red wire so that its long enough to solder to the remaining anode. Strip and solder it there.

Cut the green wire so that it can reach pin 13 of the component bank at U6. You can sloder to the component's lead if you wish. Strip and solder.

Cut the black wire long enough to reach pin 27 of U5. Once again, strip and solder.

 

Now for the testing:

 

With all of that done, you're ready to test the mods. Plug in the Supercharger, then connect the fluke leads on either side of the resistor so that the black lead is hooked near U3 and the red near U5. Set the fluke to measure DC volts, then hit the Atari's power. You do not need to set DevOS to play a 2600 game, just hit the power. (If you don't know what DevOS is, then you don't have to worry about this.)

The Supercharger will power up. If the screen is normal, then everything is good so far. Check the voltage on the fluke. If it's between 0 and 2.5, then you're good. If the screen is NOT normal, then the voltage you're measuring is probably too high. Take another 20K resistor from the pack and solder it in parallel to the first one. I literally mean that, solder them so that it looks like current should flow through BOTH resistors (because if you do this right, it will). Try it again. The voltage should be lower this time, too.

 

Now let's hook the SC to your sound source. You know the drill, set volume and tone controls to max, then play the file. MAKE SURE to reset them when you are done!

Flip the switch so that its lever is toward the component side of the SC board. You should be able to load a Starpath game into the supercharger and play it normally. If it crashes at any point, flip the switch and try again. I used Escape From the Mindmaster. It will crash just after the title screen if the switch is wrong. If that happens, flip the switch back and try again. The Starpath game should load and play correctly.

Now flip the switch to the opposite position from the one that you played your Starpath game in. Use playbin to load Atari's release of Pac-Man into the Supercharger. Yup, non a non Starpath game just made its way into your supercharger! If the switch is in the correct position, Pac-Man will play normally (and it will still suck). If the switch is wrong, Pac-Man will crash as soon as you try to start a game.

 

If it passes all the tests, then you're ready to reassemble the SC. Ensure that the switch, the audio wire, and the SC board are in the lower part of the case correctly, then carefully close up the SC like a book. Tighten down the nut on the switch, then replace the screw. If you peeled the label off, cover the entire area with the stick glue and press the label back into place. If not, you might throw some paint on the screw head to make it match a little better. Mine's still silver.

 

That's it! thanks to Bob Colbert, batari, Chad Schell (for his work with the Cuttle Cart and getting the audio files into both it and the supercharger) and anyone else who's worked with the supercharger to make this mod possible.

Edited December 18, 2007 by shadow460

[+batari]

Awesome! Glad it works.

 

2.5v may be perfectly fine. A typical VIH=2v. (VIH is the minimum voltage for logic 1.)

 

Now that you've done this successfully, I will probably go mod my own SC.

[shadow460]

Definitely post the results. I'd love to know what size resistor you use and what the output of the OR gate is.

[Sincity]

Ok. I'm lost. How does this differ from Bob Colbert's mod?

[shadow460]

This mod uses parts that can still be found at Radio Shack. I think my instructions are a little more complex, but I didn't have to wait for parts to ship in from Best.

 

The first mod listed in this thread has some fun extras to it, like an LED to tell you what mode the SC is in, and the board in that mod looks professionally done.

[Sincity]

I see. I ended up buying the IC the Mr. Colbert uses at Ebay.

Edited May 18, 2008 by Sincity

[Mark Wolfe]

Wow, great thread. I thought I was the one who thought of the audio mod, I didn't know anyone else was doing it or had even thought of it. The female stereo 1/8 jack instead of a clumsy mono wire or adapter is really the only way to go, especially since it's so dang easy, even those that can't do the main mod like myself can do that one.

 

Supercharger enthusiasts may find these threads very handy:

 

http://www.atariage.com/forums/index.php?s...=125293&hl=

 

http://www.atariage.com/forums/index.php?s...c=65897&hl=

[Sincity]

Wow, great thread. I thought I was the one who thought of the audio mod, I didn't know anyone else was doing it or had even thought of it. The female stereo 1/8 jack instead of a clumsy mono wire or adapter is really the only way to go, especially since it's so dang easy, even those that can't do the main mod like myself can do that one.

 

Supercharger enthusiasts may find these threads very handy:

 

http://www.atariage.com/forums/index.php?s...=125293&hl=

 

http://www.atariage.com/forums/index.php?s...c=65897&hl=

 

I agree that the female 1/8" is the way to go. I was too lazy to open up the SC and solder it in so I hacked the existing cable.

[Mark Wolfe]

I finally got my audio hack done. Here is a closeup of the part I used for the audio mod. The tab sticking out of the top is the SLEEVE. I cut off the round part of the tab and then bent the prong down in to the RING connection, thereby bridging the two and connected the bare wire GROUND to the RING post.

Then I attached the white wire to TIP.

 

and it was as easy as that. the bottom base should be flush with the SuperCharger's circuit board and I was able to directly solder the RING post to the back solder point of the circuit board.

 

it works great.

Edited June 7, 2008 by Mark_Wolfe

[Sincity]

That is the "cleaner" way of doing it. Good job, Mark!

[shadow460]

So have you still got the ring and ground connected? It needs to have the ring and tip connected, or you could just let the ring "float". That jack you used would be perfect for use with a 1/8 inch male dubbing cable.

 

Have you tried the other mod yet?

[Mark Wolfe]

So have you still got the ring and ground connected? It needs to have the ring and tip connected, or you could just let the ring "float". That jack you used would be perfect for use with a 1/8 inch male dubbing cable.

 

Have you tried the other mod yet?

 

The ring and sleeve are bridged and grounded. Tip caries signal . The only problem would be if I fed it a true stereo signal with one side carrying tone and the other with nothing but all my MP3s on the iPOD are mono so they feed the same signal to both channels, so it works perfectly. The whole reason I did it was to be able to get rid of the clumsy mono cable and use a short stereo cable that won't cause problems with my iPOD or laptop.

 

My SC is modded in the other way as well, but I had a friend from atariage do it for me not too long ago. I've also got my 4-switch 2600 A/V modded and I did that one myself with a kit.