Guide: How To Modify A Model 1 Sega Genesis (with pics!) - 56k Unfriendly!

*Before I begin, I want to thank the numerous people here on Sega-16 that have helped me in my quest to successfully mod a SEGA Genesis model 1, sparking a passion that has become my new focus in life. Without you all, I doubt I would have had the patience to attempt this project, and it's my hope that I can now pass what I've learned onto those that wish to follow a similar path. Thank you.

OK, so here we go...

This guide will teach you the basics on how to mod a Model 1 Sega Genesis with AV outs, S-video out, JP/US region switch, overclock switch, and finally, a halt switch. The model I'm using is a VA2, but I will explain any differences with further revisions as best as I can. That said, let's dig in.

This is the unit we will be working on today:

http://img.photobucket.com/albums/v4...201/Genny1.jpg

Step 1: Preparation

First, clear out a suitable workspace where you can strip and cut wire, solder, drill, glue, and carve comfortably. For this, I used an old dining table that we were going to throw out. Also, make sure you have proper lighting for the job - you will need to see in some tight spots on the Genny; you'll need good lighting to make out certain contact points on the console.

You will also need the following tools:
-Screwdriver set
-Soldering iron (~30w)
-Desoldering iron (~30-35w)
-Desoldering braid
-Painter's tape (1")
-X-Acto knife
-Wire cutters
-Wire stripper
-Electrical tape
-Piece of smooth glass to cut on (A picture frame is ideal).
-Ruler
-Glue gun
-Cordless drill w/ multiple bits
-Dremel or similar cutting tool
-Approx. 5' of stranded copper wire - ~28 gauge; CAT5/5e/6 is the best option for this.
-Fine point sharpie or similar marker
-Sponge or soldering station.
-Caffeine to keep your senses sharp. I use Coke Zero.

In addition to the items listed above, you will need the following components to complete the multiple modifications on the unit:

-(1) 5mm LED (whatever color/brightness you want)
-(1) Set of red, white, & yellow RCA panel mount 1/4" jacks (can be found at Radio Shack, Digikey.com, or various other retailers)
-(1) 4-pin mini-din female connector (I used Digikey part CP-2740-ND)
-(2) Single pole, double throw toggle switches (Radio Shack part number 275-613). Try to get the bushing (the threaded part) as close to 1/4" as you can.
-(1) Push on/push off switch. Make sure you don't get a momentary switch; this is for the halt switch and needs to have a locked on/off position (I used Radio Shack part number 275-1565).
-(1) 6.3v, 220uF aluminum capacitor.
-(1) 2N3904 general purpose transistor.
-(1) 75 Ohm resistor (value can be modified as desired).
-(1) 25 Ohm resistor (value can be modified as desired).
-(1) Oscillator for your overclock - I suggest 10-12 Mhz.
*Note - some processors will not work with a higher clock speed, while others work
just fine. You may have to experiment a bit.
-(1) Project board. Any size is fine - you'll be cutting it down anyway. Just get one you're comfortable working with.

Still with me so far? Good, because we're just getting started.

Step 2: Opening The Case

Materials Needed:
-Screwdriver set

Taking off the case is a relatively easy process. Start by removing the 6 case screws on the underside of the console shown here:

http://img.photobucket.com/albums/v4...1/ff50567d.jpg

Store the screws in a safe location for later - we will need them to reassemble the case. Now, flip the console back over and CAREFULLY lift the top of the case up until you feel resistance coming from the top center of the shell. This is the LED, and it's attached to a wire with bent leads to keep it in place as shown here:

http://img.photobucket.com/albums/v4...1/9b59774d.jpg

To get the unit open you will have to feel towards the top of the inside of the console where the wire and the plastic meet, until you can feel two bent metal wires, one on either side of the LED. Gently bend those down and straight, then wiggle the connector attached to the wire so that it comes off of the LED leads altogether. Once the top is removed, you should be left with this:

http://img.photobucket.com/albums/v4...1/ccab4a3f.jpg

Note the white connector in the center of the system attached to the red and white wires? That's what's attached to the LED on the top cover of the Genesis.

TAKE NOTE: In order to reattach a new LED properly, take note of which color wire is attached to each lead. One wire is longer than the other - this is called the anode. On my console, it's attached to the red wire. YMMV.

Inside shot of the top of the Genesis shell (the anode is on the left):

http://img.photobucket.com/albums/v4...1/11f357a5.jpg

Set the bottom portion of the Genesis aside for now - We're going to prep the top for modification.


Step 3: Preparing The Case, Part 1

Materials Needed:
-Smooth piece of glass
-Painter's tape
-X-Acto knife
-Fine point sharpie.

http://img.photobucket.com/albums/v4...1/b6ccdc9c.jpg

In this section, we will detail the procedures needed to prepare your case to accept your input jacks and switches. To begin, lay out your piece of smooth glass and adhere a ~6" strip of painters tape to it as shown here:

http://img.photobucket.com/albums/v4...1/4f2453f0.jpg

Then, section off a 5.5" strip of tape using your ruler and mark it off with the Sharpie. Cut off the ends using your X-Acto knife and the ruler as a guide. Then, going from left to right, mark off the following points:
1 - 0.25"
2 - 0.75"
3 - 1.25"
4 - 2.00"
5 - 2.75"

Now, going from the right side and working left, mark off the following:

1 - 0.50"
2 - 1.25"

When you're done, the tape should look like this:

http://img.photobucket.com/albums/v4...1/7af05c3f.jpg

Finally, we will need to draw an intersecting line 0.50" high to mark off the exact points where we will need to drill our holes for the jacks. The result should look like this:

http://img.photobucket.com/albums/v4...1/ae487f68.jpg

Moving forward, take the tape and carefully lay it against the top cover of the Genesis Console. When adhered, it should look like this (sorry about the flash):

http://img.photobucket.com/albums/v4...1/13b4ea32.jpg

Now, take your handy dandy X-Acto knife and CAREFULLY place the tip of the blade into each intersecting point on the painter's tape, twisting the knife to create a small guide point for the next step. If you want to have your jacks looking nice and aligned, then this step is a must.

http://img.photobucket.com/albums/v4...1/61c9c298.jpg
Up close shot of where to make holes.

Now, using the smallest drill bit you can find:

http://img.photobucket.com/albums/v4...1/25be6935.jpg

CAREFULLY drill holes into each of the guide points you made. This will make the next step much easier. By now, your case should look like this:

http://img.photobucket.com/albums/v4...1/d776f748.jpg

You can clamp the shell down to something if you have the proper equipment, but beware of scuffing/cracking it in the process. Personally, I didn't feel it was worth the risk. Moving on...

Using a 1/4" drill bit, widen the holes in the case using the guide hole as a starting point. The end result should look like this:

http://img.photobucket.com/albums/v4...1/5ab46774.jpg

My holes are a little off (it looks worse than it is due to the curvature of the Genesis itself), but the whole thing will look fine once the switches/jacks are installed.

Now, using a 7/16" drill bit widen the 4th hole from the left and the second hole from the right, as the jacks for these are slightly bigger. Here's a pic of the hole sizes; don't worry about the switches in this pic just yet - we'll get to that soon enough.

http://img.photobucket.com/albums/v4...1/ade4915d.jpg

That covers the preperation for the jacks and switches, next up is the LED assembly and installation.

By the way, if you're not matching up to what I'm showing you in this guide, feel free to drop me a PM. I can't guarantee I'll get you immediately, but I'll help out as much as I can.

Step 4: Preparing The Case, Part 2, & LED Installation

Materials Needed:
-Wire cutters
-Drill & drill bits
-5mm LED
-Glue gun

Now we're getting into the actual modification of the system, and the easiest place to start with is the LED. Replacing the LED is a relatively simple process, while adding a level of customization to the project.

http://img.photobucket.com/albums/v4...1/1dd2691c.jpg

Personally, I go with a 2500 MCD red LED to light up a dark room, but others have used blue, yellow, and green, as well.

First things first - heat up your glue gun so you won't have to later:

http://img.photobucket.com/albums/v4...1/e543754a.jpg

Now, let's go back to the picture of the LED I referenced earlier:

http://img.photobucket.com/albums/v4...1/11f357a5.jpg

You can see it's sealed underneath the plastic of the console. What we're going to have to do is drill it out. I started by cutting the leads and using a 1/16" drill bit, carefully drilled inbetween the cut leads spacing to expose the LED underneath. Don't worry if you break the LED - we're replacing it anyway. If the LED doesn't come out using the 1/16" bit, keep going up in size until you get a size that works.

http://img.photobucket.com/albums/v4...1/3567dd17.jpg

Mission accomplished.

Once the LED is out of the system, use your drill to widen the LED hole on the Genesis case itself. I used a 5/32" bit and went up in size from there, making sure the LED was snug. Here's an extremely blurry pic, but as long as you get the idea, it'll do for now:

http://img.photobucket.com/albums/v4...1/97aaf869.jpg

Remember to keep in mind which side the anode goes on and to seat your LED accordingly. Once you feel it's in a good spot, use your now hot glue gun to seal that sucker in place:

http://img.photobucket.com/albums/v4...1/29d4d479.jpg

All we do now is wait for the glue to dry and that's your first mod out of the way! Now would be a good time to test your work before we go any further.

Step 5: Fitting & Securing the Jacks/Switches

Materials Needed:
-Red/White/Yellow RCA jacks
-S-video jack
-(2) SPDT switches
-Push button on/off switch
-1/4" Rachet or wrench (optional)

Now that the glue has dried on your LED, and you've made a mad dash to your nearest television to ensure that it works, it's time to secure the RCA and s-video jacks, along with the region and OC/halt switches.

http://img.photobucket.com/albums/v4...1/ca88774f.jpg

Starting with the RCA jacks on the left, unscrew the bolts, washers and grounding tab from each jack, setting them off to the side in an accessable place. Next, fit the jacks to the first three holes in your desired configuration, so that it looks like this:

http://img.photobucket.com/albums/v4...1/543c246a.jpg

Next, secure the grounding tab and washer to the jack using the bolts you've set aside earlier. On my system, the way I fit the components was having the grounding jack on the innermost position, the washer on top of it, then tightning the bolt around them both. Try to set your grounding tabs so that they're sticking straight up out of the case - it'll make things easier later on. For the actual input tabs on the center of the jacks, just make sure the holes are accessable. Hand tighten them as best as you can, until you're sure they're where you want them to be, then use additional tools if needed. By now, your mod should look like this:

http://img.photobucket.com/albums/v4...1/cdd0c434.jpg

Note the position of the tabs on each jack.

Skipping over the s-video mount for the time being, use the next two holes to attach the two SPDT switches to the case. The bushing on my switches was too small to accomodate the two bolts included on the switch, so I removed one to make more room, but I kept the locking washer on the inside, and the standard washer on the outside, all held by a single bolt, as shown in the pics here:

http://img.photobucket.com/albums/v4...1/bc0f50cc.jpg

http://img.photobucket.com/albums/v4...1/a4bbcfcc.jpg

You can align the base of the switch any way you want; I just thought mounting them vertically would be easier for me to reach the tabs.

http://img.photobucket.com/albums/v4...1/0d45589f.jpg

Next, take your on/off switch and mount it in the hole closest to center of the console. Please try to use the same part I used (Radio Shack part 275-1565), as other switches seem to have lower shafts, causing you to potentially cut off one of the screw mounts on the case. Again, secure it the way you want, and tighten as necessary.

A quick shot of the outside of the case:

http://img.photobucket.com/albums/v4...1/f6eb3cfe.jpg

Now, onto the s-video jack. I saved this one for last, because this is the one part I've found to have a whole variety of sizes, making it's installation a bit more difficult than the others. For the part I'm using (Digikey part number CP-2740-ND):

http://img.photobucket.com/albums/v4...1/f290cdee.jpg

I'm going to take my trusty X-Acto knife and carve the hole on the console out so that it can fit the part just right (You could use a drill, but I don't have the right size bit) like so:

http://img.photobucket.com/albums/v4...1/2aeb9264.jpg

Once complete:

http://img.photobucket.com/albums/v4...1/3420eb58.jpg

I test fit the jack:

http://img.photobucket.com/albums/v4...1/c657a7ca.jpg

Looking good! Be sure to take your time on this part, as you can always cut more plastic off if it doesn't fit, but once you go too big, it's hard to cover your mistake.

Note: this jack does not have a threaded barrel, so I'm going to gorilla glue it in place once we're ready to re-assemble the case. For now, i'll just set remove it from the case and set it off to the side.

Congratulations! You've now completely prepped and assembled the connections for your case! Be sure to tighten anything that needs tightning now, as it'll get harder once we start wiring things up.

Step 6: The JP/US Region Mod

Materials Required:
-X-Acto knife
-Soldering iron
-Desoldering iron/desolder wick
-Solder
-Sponge, slightly damp or soldering station to wipe excess solder off.
-Assorted wire (I used solid brown, solid
orange and striped orange from a Cat 5 cable)
-Wire stripper
-Wire cutter (to cut off excess where needed)
-Electrical tape (optional)

Ok, this is where things start heating up, literally. Plug in your soldering iron and place it in a safe place away from everything. I can't tell you how many times I've made accidental marks on my consoles due to my being careless with the iron.

While that's going on, locate your region jumpers, which are conveniently named JP1, JP2, JP3, & JP4. JP1 & JP2 are the two jumpers we're concerned with (the other two are used if one wishes to install a 50/60hz mod). Note: depending on which board revision you have, you MAY have a capacitor soldered on JP1. This is ok, but you do need to be extra careful with the soldering iron.

http://img.photobucket.com/albums/v4...1/b381d1cc.jpg

PLEASE NOTE: Up until now, the mods we have completed do not affect your console's playability in any way. The remainder of this tutorial is designed to make permanent changes to your motherboard, which can result in a catastrophic failure if performed incorrectly. DO NOT attempt these mods if you do not have a basic understanding of soldering, or if you do not feel comfortable in completing said modifications. I do not take ANY responsibility in what happens to your system as a result of this tutorial, and I will NOT compensate for any damages accrued as a result!

I'm pretty sure Sega-16 feels the same way, too. Common sense, people. If you can't do it, find someone who can. Now that that's out of the way... Once the jumpers are located, take your X-acto knife and sever the trace between the two points on JP2, as shown above (You can see the copper trace cut in half). Be careful not to cut too deep, and be careful to avoid cutting anything else in the area, as it could permanently damage your system board. Now, looking at the jumpers so that the lettering is oriented correctly, place some extra solder on both points of JP2, and the right point on JP1. Now, strip off a 1/8" of brown wire down to the copper and tin the wire using your soldering iron. attach it to the LEFT side of JP2. Attach the solid orange to the RIGHT side of JP2, and the striped white to the RIGHT side of JP1. Once completed, you should have something like this:

http://img.photobucket.com/albums/v4...1/765859de.jpg

What I've done is taped the wires to the smooth parts of the motherboard, but you can feel free to place the wires anywhere you wish. Just remember, your wire management needs to have some sort of order, otherwise you'll wind up with a nest of wires and you won't be sure what goes where. That said, run your wires up the side of the system. Place your console top upside down so that you have something that looks like this:

http://img.photobucket.com/albums/v4...1/8b0c7aa9.jpg

Strip off approx 1/4" of shielding from each wire and attach them to the SPDT switch next to the s-video jack so that: The brown wire (common wire) is attached to the middle, while the solid orange (US) and striped orange (JP) are on either side of the switch. Solder them in place and make sure they're secure.

http://img.photobucket.com/albums/v4...1/7b561c56.jpg

Again, now would be a good time to test your system. A good test to run would be to boot a game you know is region locked, like Street Fighter II: CE. When in US mode (on a US console, obviously), the machine should boot as normal, while when placed on JP mode, you'll get a red warning screen stating that the game is made for North American consoles only. If you get this, then you've completed your region switch mod!

Drink some Coke (Zero), you deserve it.

Step 7: The Halt Switch

Materials Required:
-Soldering iron
-Desoldering iron/desolder wick
-Solder
-Sponge, slightly damp or soldering station to wipe excess solder off.
-Assorted wire (I used solid orange and striped orange from a Cat 5 cable)
-Wire stripper
-Wire cutter (to cut off excess where needed)
-Electrical tape (optional)

The goal of this tutorial is to ease you into the mods of the system, starting with the most basic mods, then working up to the more difficult ones. in retrospect, these last two steps could have been reversed, but I guess it works out either way. In any event, on with the show!

The halt switch is a useful tool to have when experimenting with over clocking the CPU. Essentially, what a halt switch does is it tells the CPU to stop whatever it's doing and remain in that state until you tell it to go again. How this relates to the CPU overclock is that, if you try to throw the overclock switch (covered later in the tutorial) from 7.67 MHz (stock speed) to whatever speed you settle on for the over clock and vice versa while the system is on, it'll crash whatever game you're playing because the CPU wasn't ready for that change. The halt switch allows you to halt the CPU, switch the speed safely in-game without restarting, and resume as normal, with the new speed intact. In addition to this, I've also discovered that as of OS16, the Sega Everdrive does not allow you to access your game menus aside from "start game" without locking up. This makes the halt switch a MUST have, otherwise you'll have to boot up in normal mode, select a game, flash it, start the game, then turn the Genesis OFF, throw the OC switch, boot back up and choose start game to get it into OC mode, whereas with the halt switch, you can start in normal mode, select your game, flash it, halt the game once it's started, throw the OC switch, then resume as normal.

You probably didn't want to hear all that, but, hey, it's my tutorial. :)

Back to work...

In order to enable the halt switch, you will have to solder two wires - again I used solid and striped orange - to the on and off contacts of the switch. The striped wire is a ground, and can be soldered anywhere along the metal strip you see on the border of the Genesis. The solid orange wire, however, needs to be soldered to pin 17 of the processor, as shown below:

http://img.photobucket.com/albums/v4...1/b0cd7d32.jpg

(Ignore that brown wire, that's coming up in the next step.)

This pin is the halt pin, which is what we want to access with the halt switch. Once these two wires are soldered in place, it's once again a good time to test your work before moving on. While playing a game, hit the halt switch and see if the game freezes, then see if it unfreezes once you hit the switch again. if so, then you're good to go. If not, double check your wiring and try again. You may have the wires soldered to the wrong contacts - I've been lucky in that each time I solder the wires to the contacts, pressing the button in halts the system, and pressing the button out resumes play.

Here's your end result:

http://img.photobucket.com/albums/v4...1/41c81e5d.jpg

Got it? Good! Onto the AV stuff...

Step 8: Composite Video & Stereo Out Mods

Materials Required:
-Soldering iron
-Desoldering iron/desolder wick
-Solder
-Sponge, slightly damp or soldering station to wipe excess solder off.
-Assorted wire (I used solid brown, solid orange, striped brown and striped orange from a Cat 5 cable)
-Wire stripper
-Wire cutter (to cut off excess where needed)
-Electrical tape (optional)

The Sega Genesis is capable of producing stereo sound through its headphone jack, so this is where we will tap into in order to produce a stereo out on the back of the console. Look for the headphone jack on the bottom left of the unit, and take note of the numbers listed beneath it:

http://img.photobucket.com/albums/v4...1/8bb7120a.jpg

As documented by David Howland on his website http://www.davidhowland.com/mod/ the numbered points on the headphone jack correspond as follows:
1-Ground
2-Right
3-Left

This is what we will be attaching our wires to. Go ahead and prep the wires by stripping off 1/8" of the ends of the wires and tin them using your soldering iron. Then, carefully turn the system board over so as not to tangle your previous wiring and look for the same points we just noted on the front side of the system board. This is where we will be soldering our wires.

http://img.photobucket.com/albums/v4...1/ece591c5.jpg

You can use any point on each of the traces for their respective value. I just used the main solder points.

Melt a bit of fresh solder onto each of your contact points to make the soldering easier, then attach your wires to the contact points Again, I used striped brown for ground, sold orange for right, and striped orange for left. Now beneath the solder points you should see an oval shaped hole. Run your wires through it like this:

http://img.photobucket.com/albums/v4...1/0bf92e83.jpg

This will help them stay together a bit easier. Again, run the wires up the side of the board (not pictured, I figure you know how to do this by now), and guide them towards the composite and audio outputs. From here, it's just a simple matter of wiring them up. Start by attaching the ground wire (striped brown) to the grounding tab on the first jack closest to the center. Now, as shown in the pic below:

http://img.photobucket.com/albums/v4...1/0ca3267d.jpg

You also need to run the ground to the other two tabs, as well. For this, I just tied a few small pieces of wire together, creating a bridge for all three holes, then soldered them into place. Then, to complete the audio side of things, attach the orange and striped orange wires to their respective locations. You should get something that looks like this:

http://img.photobucket.com/albums/v4...1/228e30da.jpg

Now to complete the composite mod, you will need to flip the board over again. This time we're looking for the AV out jack, as shown here (Courtesy of David Howland, as I forgot to take a pic):

http://img.photobucket.com/albums/v4...dconnector.jpg

Once again, flip the board over to expose the underside of the console. The pin we're looking for is pin 3, which is located on the top left corner of the set of pins attached to the video encoder, as seen here:

http://img.photobucket.com/albums/v4...1/1f6b9b3d.jpg

Again, melt some solder onto the contact point and after tinning your wire, attach it to pin 3, like so:

http://img.photobucket.com/albums/v4...1/1e5b0688.jpg

Find a good spot to run the wire up and around the system board and attach it to the video (yellow) contact on your Genesis. Here's a shot of the completed circuit:

http://img.photobucket.com/albums/v4...1/cd9dd2b0.jpg

Again, this is a good time to double check your work and make sure your jacks all work as they should. Make any appropriate changes and get another Coke (Zero); we're almost there!

Step 9: Setting Up S-video and Overclocking the Genesis, Part 1

Materials Required:
-Soldering Iron
-Desoldering iron/desolder wick
-Solder
-Sponge, slightly damp or soldering station to wipe excess solder off.
-Assorted wire (I used soild brown, solid blue, solid green, solid orange, striped brown, striped blue, and striped green from a Cat 5 cable)
-Wire stripper
-Wire cutter (to cut off excess where needed)
-6.3v 220uF capacitor
-75 Ohm resistor
-25 Ohm resistor
-2N3904 transistor
-xx.xx Mhz oscillator
-Project board
-Electrical tape (optional)

Now we get into the meat and potatoes of why we're really here - to add in options that normally wouldn't come with the Genesis in some way shape or form. The previous mods were all based on existing hardware built into the board, but the next two steps require some additional hardware added into the unit to really make it shine. This step mostly covers the s-video mod, which provides a noticably clearer picture over composite and RF, resulting in a bright, clean picture coming from the console. You'll also prepare the system for the overclock mod, as well.

To start, you will need a project board. As I stated above, most any size will do, as you're going to file it down when we're done, anyway.

http://img.photobucket.com/albums/v4...ojectBoard.jpg

This is the one I used, I just used the dremel to cut it in half.

Now, there are a few ways to get s-video out of the Genesis, but the easiest and most effective way I've come across is the method described right here, at Sega-16.com.

As shown in Jaxmazon's thread, Villahed94 outlines the details of creating an s-video circuit. To begin, you will need to place the 6.3v, 220Uf capacitor on to the top center of the board, with the shorter leg to the left hand side when looking at the board from top down. Strip off ~1/4" of solid green wire and twist the bare wire around the short leg of the capacitor, ensuring the two components are well connected, then solder them in place. Next, take your 75 Ohm resistor and solder a leg (it doesn't matter which one) to the long leg of the capacitor. Leave the other leg on the resistor alone for now. Cut the excess portions of the legs off using your wire cutter This is your chroma signal.

http://img.photobucket.com/albums/v4...1/6aa84b85.jpg

The picture above serves two purposes: first, it's meant to show you where the capacitor and resistor are meant to be and secondly. it sets us up for the 2nd half of the s-video mod.

Take the 2N3904 (or compatible) transistor and place it so that the domed surface is facing away fom the capacitor when standing straight up. Bend the legs in such a fashion that the domed surface folds downward towards the capacitor, until it looks like the picture shown above.

Going from left to right: the three legs (when looking top down as in the picture) are: collector, base, and emitter.

Please note: Depending on what transistor you wind up using, make sure of the values of the legs, as they can change from transistor to transistor.

Now, take the brown wire, and, just as above, strip 1/4" off and wrap the exposed wire around the collector pin, soldering it in place. Then, repeat the process using the solid blue wire and the base pin. Finally, wrap the 25 ohm resistor around the emitter and solder that into place. This is your luma signal. Again, refer to the picture above for reference.

This next step doesn't have anything to do with s-video, but it's important we cover it now before we permanently attach wires to the system. I'm talking about the overclock oscillator.

A quick note about oscillators: While modding systems, I've found that, for what ever reason, some processors do not work with higher clock speeds, and others do. This is not dependent on processor model, either - for example, I've overclocked a Signetics CPU on one system to 12 Mhz, but a 12 Mhz signal on a different Signetics CPU only works at 10 Mhz or lower. I've seen people clock their systems up to ~26 Mhz, but they're mostly glitchy and only for bragging rights. In short, you may have to play around a bit with the value of your oscillator to get things right. Personally, I would order a couple different speeds to test them out - they're cheap enough and will all eventually be used if you plan on doing more than one console.

Ok, now that that's out of the way, let's go ahead and attach the oscillator (I used a 10 Mhz, half size) towards the bottom center of the circuit board. The small circle indicates pin 1, and pin 1 should be oriented on the bottom left portion of the circuit board. This pin also carries no signal from anything, so it can be soldered immediately to help hold the chip in place. Now, going from the bottom left (pin 1) counter clockwise, the pin to the right is pin 4, directly above it is pin 5, and to the left of that is pin 8. Pin 4 is ground, pin 5 is signal out, and pin 8 is a 5 volt signal.
Strip 1/4" off of the following and solder: the striped brown wire to pin 4, the solid orange wire to pin 5 and the solid brown wire to pin 8. When you're done it should look like this:

http://img.photobucket.com/albums/v4...1/b984a3c6.jpg

If not, fix it and let's move on.

So by now, we should have a completed s-video and over clock circuit created on your project board. Now we just need to file down it's size and attach it to the various points on the motherboard. I used a Dremel to cut along the holes next to the outer most points of my circuit and cane up with a much smaller size that fits easily in the system.

http://img.photobucket.com/albums/v4...1/b2bbe032.jpg

Now, focusing on the s-video portion of the mod, we will need to remove the heat sink attached to the mother board and voltage regulators. This is the large silver item in the upper left corner:

http://img.photobucket.com/albums/v4...1/a1841a57.jpg

Remove the two screws that are attached to the voltage regulator:

http://img.photobucket.com/albums/v4...1/b686602c.jpg

And the two corresponding screws underneath the unit:

http://img.photobucket.com/albums/v4...1/3b9ea92a.jpg

There may be a couple more screws to remove, if you haven't already from the initial disassembly.

Once we have the heat shield off, locate your video encoder chip, which should be labeled "CXA1145." Take note of the orientation of this chip; VA2 and Va3 boards have pin 13 on the lower right corner, while VA6 boards have pin 1 in the same spot. These are the only models I've worked on, so there may be other variations. In any event, locate pin 13 (there should be a number 13 listed next to it) and count up (or down, depending on the chip's orientation) two pins to pin 15. This is your chroma output, and pin 16 is your luma output.

http://img.photobucket.com/albums/v4...1/e62e9764.jpg

(Note the "13" marking to indicate pin 13. two pins to the right is pin 15, followed by pin 16.)

Melt a small amount of solder onto both pins 15 and 16 (this can be tricky if you have pins 15 and 16 on the side with all the capacitors, so be careful), then strip, tin, and solder the wires from your circuit to the proper pins on the video encoder. Remember, green is chroma, blue is luma. Trim any excess wire; we'll need it.

http://img.photobucket.com/albums/v4...1/29e6b6f7.jpg

If the pic looks like the one above (or slightly altered for a flipped chip), we can now solder the luma and chroma wires onto the resistors on the opposite side of the project board. These are the signal wires that will run to the s-video jack. Leave them be for now, just make sure they're long enough by test running them to the jack.

before finishing up the s-video side of things, we will need to wire a +5v signal to the collector wire (brown) attached to the transistor. We can obtain this signal from one of the voltage regulators.

Looking at the system board where the voltage regulators connect, you should see something that resembles this:

http://img.photobucket.com/albums/v4...del%201/VR.jpg

The numbers 1,3 and 2 should be beneath the three legs. We're going to tap into point 2, or the output. You just need to solder a wire onto this leg and we're good to go, but just be careful that you don't get the wire in the path of the heat sink we still need to put back on. What I did is soldered the wire to the underside of the board, and insolated it with tape around the areas where it would be touching the heat sink to avoid grounding out the signal, and taping it as flat as possible to the system board.
http://img.photobucket.com/albums/v4...1/3c1be64c.jpg

The other wire is for the oscillator, which we will cover in the next step.

Next, we'll need to attach the luma and chroma wires to the s-video jack. The following diagram is as if you're looking at the connector, rather than from behind at the tabs (via image.pinout.net):

http://img.photobucket.com/albums/v4...eo_pinouts.jpg

What this means is that we have to actually reverse the values in order to determine where to solder the wires. More specifically, when looking at the back of the s-video jack the luma connection is the one on the top left, and the chroma connection is the tab on the top right. The bottom two tabs are ground and can be interchanged at will.

Here's luma and chroma:

http://img.photobucket.com/albums/v4...1/f101b478.jpg

And here's the whole thing wired up:

http://img.photobucket.com/albums/v4...1/8a790d6f.jpg

Notice how I haven't mounted the jack into the unit just yet - that's because these tabs are hard to solder onto, and it's easier to do it out in the open then glue the jack in place later (now would be a good time to do so if you feel comfortable with your work).

That about does it for s-video. You definitely want to test your work on this one - this is probably the most complex mod (not necissarily complicated), and it's easy to overlook a thing or two. Plus, it's always nice to get your first glimpse of what s-video looks like on a Genesis. :)

We're entering the home stretch! There's only a few more wires seperating us from a fully modded Genesis!

Step 10: Overclocking the Genesis, Part 2

Materials Required:
-Soldering Iron
-Desoldering iron/desolder wick
-Solder
-Sponge, slightly damp or soldering station to wipe excess solder off.
-Assorted wire (I used soild brown, solid orange, and striped brownfrom a Cat 5 cable)
-Wire stripper
-Wire cutter (to cut off excess where needed)
-Electrical tape (optional)

Since most of the work has already been done in step 9, this step should be a piece of cake. Essentially, what you want to do is to wire the clock signal from the processor to the switch, along with the two clock speeds, standard and overclock. To accomplish this, you must disconnect pin 15 on the CPU from the system board. You can unsolder it from the under side of the board using a desoldering wick or desoldering iron, you could sever the trace on the motherboard, just like you did with the region mod, or you can do what I did and use a screw driver to break the pin from the board, as shown here:

http://img.photobucket.com/albums/v4...1/b0cd7d32.jpg
(Yes, I used the same image twice. Sue me. ;) )

Once that has been done, melt some solder onto pin 15 and solder the brown wire shown in the picture below to the center of the remaining switch on the Genesis:

http://img.photobucket.com/albums/v4...1/85935fd2.jpg

Do the same for the orange wire coming from the oscillator for the overclock signal. For the remaining stock signal, you will have to turn the board over one last time. Before you do, however, take a look at your cartridge slot and note where "B1" and/or "B32" is labeled. These are the first and last pins of the bottom row of contacts on the cartridge slot.

http://img.photobucket.com/albums/v4...1/85c309b5.jpg

Once you have found those points, turn the board over and, starting from either position, find pin B19 - this is the pin that generates the 7.67 MHz stock clock signal. Melt a bit of solder onto this point and solder the remaining striped brown wire into place, and then route it to the top of the board, soldering it onto the final contact of the switch. Also, during this time you should solder the remaining brown wire from the oscillator to the second voltage regulator, just as you did for the s-video mod.

Again, some reference pics:

http://img.photobucket.com/albums/v4...1/7a403394.jpg
(Pin B32 is point from on the top right of the two rows of contacts, count backward from there to find B19)

http://img.photobucket.com/albums/v4...1/3c1be64c.jpg
(Both +5v wires connected and ready to go)

That about does it! I suggest a final test before you put everything back together, just to make sure. There's nothing more frustrating than putting a system back together without testing it and it doesn't work.

Once that is all said and done, enjoy your newly modded SEGA Genesis!

I hope this guide has been thorough and helpful to anyone who reads through it. Again, as I stated at the beginning, feel free to drop me a line if you have any questions - I'll do my best to answer them. Also, feel free to drop any comments in the thread or via PM.

Until next time!

http://img.photobucket.com/albums/v4...1/2a2211e3.jpg

Good write up! An awesome spot for the S-video plug is to remove the RF shit-tin and put it there, the hole is next to the perfect size.

There are many places for the jacks & switches installation, so you won't end up with a modded Genesis non-Master System converter friendly system :bang: .... Unless you are planning to use the rare SMS converter II or a 3rd party one, might as well and put a little more effort while at it :ok:

http://usera.ImageCave.com/capcom2000/hpim8608.jpg

..

See, I actually own a SMS, so that part of it doesn't even cross my mind.

Its always handy to have the option....

urge to buy soldering iron rising

I'd do an S-Video mod for my Genesis... But I have a 32X, so there's no point. Who was selling those S-Video boxes anyways? Getting sick of composite over here. :|

EDIT: Btw, have any of you mod heads ever thought of using the EXT port on the back for AV connections? It's super easy to make a cable with a DB9 plug on it. There's room for Composite, Stereo sound, Chroma, Luma and a some grounds. No room for RGB. I suppose one might not want to use it because of the Mega Modem, but how useful is it anyway? Just a thought to use that rather juicy looking connector. :D

Personally, I'm not a fan at all of drilling holes in original cases. Once those holes are there, there's no going back. If you mod the Genesis like Lastcallhall, there's no more PBC compatibility. If you screw up drilling the holes, there's nothing you can do to fix it (well, nothing easy). I am a big supporter of 'cloak modding' (for lack of a better word), where an existing connector is used. Or in the case of the Genesis, hiding all the connectors and switches in the expansion bay on the right (not drilled, just hanging in there), but then again the Sega CD would interfere... Hmm, posterity-friendly modding of Genesis consoles is really hard.

*sigh*, I just wish there was a better way than drilling holes... Think of the original plastic shells people... :Panda:

You mean kinda like this? Has region 50/60Hz switches, AV out, S video out and MD AV out. Please excuse the home made 32X cable, I recently made a much neater one. The jiffy box plugs into the EXT port and the AV port. Looks like a growth lol but so does the 32X I suppose. I done it this way because I got this mint Asian MD in box (looked almost new!) and I didn't want to go hacking away at it willy nilly. The MD's I modify and sell through the store I do mods/repairs for is done neatly as I have jigs for everything, this one I just couldn't do it......

Quote:

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Originally Posted by Guntz

I'd do an S-Video mod for my Genesis... But I have a 32X, so there's no point. Who was selling those S-Video boxes anyways? Getting sick of composite over here. :|

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Electrochip

nice comprehensive guide mate...good shit homes.

Can you possibly do a 50/60 Hz mod? I know it's similiar to how the Jap/Eng switch works just using the other two jumpers, but I'm pretty sure it'll come out black and white and need some sort of color fix.

Quote:

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Originally Posted by cheaterdragon1

Can you possibly do a 50/60 Hz mod? I know it's similiar to how the Jap/Eng switch works just using the other two jumpers, but I'm pretty sure it'll come out black and white and need some sort of color fix.

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check out Devil N's single switch mod - 50/60+JAP/EUR/USA all on one toggle....neat :)

single switch mod

colour fix = scart cable!

....voila ;)

Quote:

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Originally Posted by ooXxXoo

Its always handy to have the option....

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No doubt, but that can be left up to the modder's discretion. This is merely a guide showing a good overview on how to mod a Genesis and where to start if one were so inclined. I'm sure if someone really wanted PBC compatibility, they'd find a way.

Quote:

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Originally Posted by Mista_Ed

nice comprehensive guide mate...good shit homes.

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Thanks!

Quote:

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Originally Posted by cheaterdragon1

Can you possibly do a 50/60 Hz mod? I know it's similiar to how the Jap/Eng switch works just using the other two jumpers, but I'm pretty sure it'll come out black and white and need some sort of color fix.

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I would, but I don't have any way of testing it. Mista Ed's suggestion is probably your best bet.

Quote:

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Originally Posted by cheaterdragon1

Can you possibly do a 50/60 Hz mod? I know it's similiar to how the Jap/Eng switch works just using the other two jumpers, but I'm pretty sure it'll come out black and white and need some sort of color fix.

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Colour fix, you will have to swap the crystal to the NTSC crystal, sorry can't remember what that is.

Attachment 2930

http://img.photobucket.com/albums/v4...201/Genny1.jpg

Now that is some beautiful, really clean Model 1 Genesis HDF. Where did you get it?


http://img.photobucket.com/albums/v4...1/2a2211e3.jpg

End result looks awesome too. Wish I had the skills to do it myself on my Genesis, but I would only need the S-Video and Composite out. Any way to actually have component out?

You need a new video encoder to use Component. The Sony CXA1145 (and alternative encoders in the Genesis) can only do Composite and S-Video. I've heard good things about the NeoBitz and JROK encoders. They are primarily used in Arcade systems for home use, but they can be used on other RGB capable machines as well.

Quote:

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Originally Posted by Jadty

Now that is some beautiful, really clean Model 1 Genesis HDF. Where did you get it?

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Thanks. I got lucky on an auction that included 8 CIB games. as well.

Quote:

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End result looks awesome too. Wish I had the skills to do it myself on my Genesis, but I would only need the S-Video and Composite out. Any way to actually have component out?

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You can do the s-video and composite out pretty easily, but like Guntz said, component is kind of tricky. You could go the J-rok route, or you could go the scart to component out, using the native RGB out from the Genesis.

I just use a Japanese 21PIN cable, image is perfect through my 230 pound CRT TV.

Wow great guide! This has definitely been on my list of things to do. Lucky for me I recently found two model 1 Genesis's for $5 each so they will be perfect little ginny pigs

That's a nice piece of work and a great guide, I always like seeing someone make a neat job of a project. Now, are you also able to do the "evil to good" mod on my T-101? You look like the kind of guy who can, he keeps trying to kill pregnant women.

Sure thing; you just need to reset the switch.

No soldering required? Nice!

Nope, you just need a steady hand, nerves of steel, a strong stomach, and lack of falling hammers/mallets in the area.

Nice guide, really helpful

Thanks!

To be honest here, I think you should do a guide showing people how to do a Power Base Converter-friendly mod to your Genesis. I'd hate to see more modded Genesis systems show up following your guide down to the exact detail.

Also, I have a couple of questions:

- Do you have to use a 6.3v 220uf capacitor? Will a 10v or 16v work? (that cap is for S-Video right?)
- Will any oscillator work? Should I get a couple of different clock speeds in case one is too fast?

Quote:

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Originally Posted by Guntz

To be honest here, I think you should do a guide showing people how to do a Power Base Converter-friendly mod to your Genesis. I'd hate to see more modded Genesis systems show up following your guide down to the exact detail.

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That's up to the reader/modder's discretion on whether or not they want a PBC friendly unit. Personally, as I explained to ooXxXoo, my perspective is that my guide is simply that, a guide. I already own a SMS (that's also s-video modded), so I have absolutely no need for a PBC friendly unit. If someone really wants that compatibility, then by all means go ahead and figure out where the holes need to be drilled. Having a PCB-compatible system is only a superficial mod anyway; it doesn't require it's own guide if only the holes are changing.

Quote:

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Also, I have a couple of questions:

- Do you have to use a 6.3v 220uf capacitor? Will a 10v or 16v work? (that cap is for S-Video right?)

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I've used both 6.3v and more recently 10v capacitors with no problems. YMMV. And yes, it's for S-video

Quote:

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- Will any oscillator work? Should I get a couple of different clock speeds in case one is too fast?

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The most I'd want to go with any overclock is 12MHz, for a few reasons, mainly stability. Anything over 13MHz is super prone to graphical glitches, system failures, and the like. Here's the thing, though, and I know other modders will disagree with me on this, but it's been my personal experience that it really all comes down to the independent processor of your machine that determines what speed you can use. I've modded Model 1s with both a Signetics processor and a Motorola processor, and each one had about a 50% success rate when attempting to overclock to 12MHz. I'm positive it's the processor because if I were to swap out the same circuit with a 10MHz processor, and changing nothing else in the design of the overclock circuit (wire length, etc.), it works fine. The other half of the time, the 12MHz processors work just fine. So in short, I'd buy a 10MHz and a 12MHz and see what works best for you. :)

Okay, thanks for all the help. :D

I forgot to ask this, but what voltage should the oscillator be? 6.6v or 3.3v? Those are the two most common I'm finding. Also, what about load capacitance? I have one that says 15 pf. Will these numbers work with the Genesis?

Sure thing. :)

Voltage should be +5v - that way you can power it with a +5v line on the Genesis.
Here's the one I used: http://search.digikey.com/scripts/Dk...&name=XC267-ND

If I'm reading the datasheet correctly, then the load capacitance you're referencing falls in line with what's shown on the datasheet.

Ah, okay. For some reason I thought the voltage was more of a "can be fed up to 6.6v" or something. Gotta stick to 5V all the time. :)

Umm, this question isn't really Genesis related, but does anybody know if the Neo Geo MVS takes a crystal or oscillator? It's just it occurred to me while I was searching for oscillators that the Neo can be overclocked too (16 MHz pretty sure). This is likely going to be my last Mouser order for some time and I want to make sure it lasts me a while.

I'm planning to try this after I get soldering lessons over the summer, but ideally I'd like to do the following:

- omit the LED (don't want) and S-Video (don't have anything that can connect to it)
- be able to switch the region to PAL too (all my carts that have region lockout are PAL, and I can't save in Soleil through a Game Genie)
- be able to do something about the LOUD pop (voltage spike) in the audio when powering on/off (maybe this is impossible)

I guess it shouldn't be too tricky to ditch the LED, and I could probably figure out which steps to skip when assembling the board for the overclock + S-video. Are there any curveballs in using a three-position switch for US/JPN/PAL? Should I just follow one of the methods linked in the earlier posts in this thread? (Lastcallhall, I've noticed you don't add that option to your mods -- any reason why?)

Quote:

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Originally Posted by goldenband

(Lastcallhall, I've noticed you don't add that option to your mods -- any reason why?)

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I really have no way of testing whether or not a 50Hz mod would work correctly. Ideally, I'd love to add the option, but from the sounds of it, it'll require another modification aside from tapping into the jumpers...

Quote:

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Originally Posted by Lastcallhall

I really have no way of testing whether or not a 50Hz mod would work correctly. Ideally, I'd love to add the option, but from the sounds of it, it'll require another modification aside from tapping into the jumpers...

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Do you have an Everdrive? If so, you could try booting up a region-locked game like Soleil, Worms, Smurfs 2, and so on. I don't think most people would need (or want) to run the game in PAL -- they'd switch it back to NTSC as soon as it passed the region check -- so getting high-quality PAL video isn't necessary (would that require an alternate crystal?).

Otherwise I'll try the one Mista_Ed linked, I guess, assuming that it's the same on a US NTSC Model 1. That one didn't seem to require any crazy additional steps...?

Yeah, that might be feasible. I'm talking with someone over at AA about buying 2 more consoles so I can test it on one of those if all goes through...

I did some searching on the Neo overclock and from the sounds of it, the Neo doesn't do well with an overclock (something about internal timing issues between the 68k, Z80 and gfx chip). I'll still get a 15 or 16MHz oscillator in case I'm feeling saucy, but I'm not holding my breath. Biggest reason why I'd want an overclock is because I love Metal Slug 2, but even more so when there's less slowdown. Metal Slug X is too different from 2 for me to play instead.

Lasthall, I`ve got a question. Did the overclock mod work on that Va2 of yours? Just to know because I`ve only modded the only ones I`ve ever got(VA6) and I`m about about to receive a VA2-VA3

Quote:

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Originally Posted by villahed94

Lasthall, I`ve got a question. Did the overclock mod work on that Va2 of yours? Just to know because I`ve only modded the only ones I`ve ever got(VA6) and I`m about about to receive a VA2-VA3

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It "worked" in the sense that the system was overclocked and didn't crash, but it distorted the PSG sound channel in the process.