Genesis 2 Model Numbers

[b1aCkDeA7h]

I was wondering if anyone out there knew if model 2 Sega Genesis' have any outward distinguishing features that would indicate it having the easy to mod Sony CXA1645M chip inside.

A friend of mine had two, one a MK-1631 with an unidentifiable chip and another that was a MK-1631A with the Sony CXA1645M inside.

I mean, this is only one situation with the two Genesis systems we had on hand. I want to see if there are more definitive outside signs as I know flea market and thrift store people kinda frown upon the opening up of their merchandise.

Any willing model 2 Genesis owners with the Sony CXA1645M chip, can you list your model number and serial number?

[izarate]

There is no sure way to tell. I have a truckload of Genesis 2s and even if they have the same serial number on the board, there is a chance of getting the SKA chip.

Anyway, I'll list the serial numbers for you:
CXA chip:
G30650691 Japan
G30666434 Japan
140234359 China
130186679 China
630468591 Taiwan
163091076 China

MB chip (also moddable):
G30650691 Japan

SKA chip (un-moddable):
163076055 China
R43020475 Japan
130557717 China
230318366 Thailand
B30391186 Japan
A36XX0421 Japan (the serial is damaged, for some reason this one has a MK-1451 model number)

Based on my data, you could say that G306s are a better bet than any other, but don't quote me on that.

[b1aCkDeA7h]

So I took my MK-1631 to a few of the local video game stores I frequent and one of them was super cool about trading in my working MK-1631 for a MK-1631A. Seems the distinguishing features I can pick out from US Model 2 Genesis systems are a model number of MK-1631A and the yellowish metallic case screws rather than the flat black ones that were on my MK-1631.

Now I've got a nice Sony CXA1645M to hopefully do what I'm told is an easy S-Video mod.

[izarate]

So I took my MK-1631 to a few of the local video game stores I frequent and one of them was super cool about trading in my working MK-1631 for a MK-1631A. Seems the distinguishing features I can pick out from US Model 2 Genesis systems are a model number of MK-1631A and the yellowish metallic case screws rather than the flat black ones that were on my MK-1631.

Now I've got a nice Sony CXA1645M to hopefully do what I'm told is an easy S-Video mod.

Many of my SKA Genesis 2 have the same SNES-like coloured screws. And I forgot to list the model numbers, but my Genesis with the MB chip has that model number (MK-1631A). The rest are MK-1631.


I really think that it's a matter of luck. I mean, for Sega, the three chips (Sony CXA, Fujitsu M and Samsung KA) were one and the same. After all, they have the same capabilities that Sega required for the Genesis (RGB, composite out). S-Video wasn't in Sega's plans.

[b1aCkDeA7h]

So I've come across three Model MK-1631A Genesis Systems and all of them have the CXA1645M chip. Just spent a day with a friend who's more used to a soldering iron than I am and with a few trips to Radio Shack, we've S-Video modded all three Genesis systems.

If it really is just the luck of the draw, then wow, I'm pretty lucky.

[izarate]

So I've come across three Model MK-1631A Genesis Systems and all of them have the CXA1645M chip. Just spent a day with a friend who's more used to a soldering iron than I am and with a few trips to Radio Shack, we've S-Video modded all three Genesis systems.

If it really is just the luck of the draw, then wow, I'm pretty lucky.

I guess so. I've seen some posts in other forums reporting 1631As with SKA, MB and CXA chips. As I said, engineering wise, the three of them were one and the same for Sega. It's just a matter of which one they had on hand at the moment of manufacturing. Of course, with Sony being based in Japan, it's possible that Japanese Genesis have a higher probability of having a CXA.

[crrimson]

So I've come across three Model MK-1631A Genesis Systems and all of them have the CXA1645M chip. Just spent a day with a friend who's more used to a soldering iron than I am and with a few trips to Radio Shack, we've S-Video modded all three Genesis systems.

If it really is just the luck of the draw, then wow, I'm pretty lucky.

What schematics / parts did you use to modify your Genesis 2's for S-Video? Will the ones listed here work?

http://www-unix.ecs.umass.edu/~dhowland/mod/

Or did you have to use any different parts? I want to mod the Genesis 2 I have, because my Genesis 1 is my first gaming system from 1989, and I would hate to risk destroying something so valuable to me . I also have a Genesis 3 and read that it's very easy to mod for S-Video, but my soldering iron is definitely too bulky for the tiny leads on that chip.

[b1aCkDeA7h]

It's funny because I essentially took a crap shot from a page that described a Genesis 3 mod for either s-video, RGB, or both. I took a chance since it had the same CXA1645M as most Genesis 3 systems do. The page is here:

Link

Went to a Radio Shack and bought a .015 dia. silver-bearing solder, 22 gauge wire, a female s-video coupler, two 220uf capacitors, and some 68 and 10 ohm resistors (since I couldn't find 75 ohm resistors). Then went to a Wal-Mart and bought electrical tape, a cheap soldering iron, and a cheap hot glue gun.

Opened up the Genesis, took off the I/O shield, soldered the wires to the leads on the CXA1645M chip, soldered the resistors and capacitors as shown on the page, cut the s-video coupler in half, soldered the capacitors to the s-video coupler half, insulated the resistors and capacitors, cut a hole on the plastic shell, mounted the s-video, and grounded it to the I/O shield.

The hardest parts to the mod were soldering the wires onto the CXA1645M chip and mounting the s-video onto the case. The aid of a steady third hand was necessary to stem the risk of accidentally bridging a connection on the CXA1645M leads. The first modded system came out sloppy, but it worked. By the time my friend and I got to the third system, it looked as if the s-video port came out the factory like that.

Honestly, modding a Genesis 1 is much more work though the umass page details what to do pretty well. I bought a modified Genesis 1 system for about $5 only to find out that the mod was done sloppily. When I tried to fix it (again, using the umass page as a reference), I found that the modder had done some very stupid things during the modding process and that his needless and sloppy globs of solder were what were barely holding the job together. Unfortunately that Genesis had to be scrapped because it was unsalvageable.

Still, in the end, I got it working and I must say, the difference in picture quality is quite remarkable.

PS:

I also have a Genesis 3 and read that it's very easy to mod for S-Video, but my soldering iron is definitely too bulky for the tiny leads on that chip.

If you can, but a more fine conical tip. That combined with a third hand made modding it easy. Keep in mind, I did this with the help from a friend and a $5 soldering iron from Wal-Mart (found in the automotive electronics section oddly enough).

[crrimson]

It's funny because I essentially took a crap shot from a page that described a Genesis 3 mod for either s-video, RGB, or both. I took a chance since it had the same CXA1645M as most Genesis 3 systems do. The page is here:

Link

Went to a Radio Shack and bought a .015 dia. silver-bearing solder, 22 gauge wire, a female s-video coupler, two 220uf capacitors, and some 68 and 10 ohm resistors (since I couldn't find 75 ohm resistors). Then went to a Wal-Mart and bought electrical tape, a cheap soldering iron, and a cheap hot glue gun.

Opened up the Genesis, took off the I/O shield, soldered the wires to the leads on the CXA1645M chip, soldered the resistors and capacitors as shown on the page, cut the s-video coupler in half, soldered the capacitors to the s-video coupler half, insulated the resistors and capacitors, cut a hole on the plastic shell, mounted the s-video, and grounded it to the I/O shield.

The hardest parts to the mod were soldering the wires onto the CXA1645M chip and mounting the s-video onto the case. The aid of a steady third hand was necessary to stem the risk of accidentally bridging a connection on the CXA1645M leads. The first modded system came out sloppy, but it worked. By the time my friend and I got to the third system, it looked as if the s-video port came out the factory like that.

Honestly, modding a Genesis 1 is much more work though the umass page details what to do pretty well. I bought a modified Genesis 1 system for about $5 only to find out that the mod was done sloppily. When I tried to fix it (again, using the umass page as a reference), I found that the modder had done some very stupid things during the modding process and that his needless and sloppy globs of solder were what were barely holding the job together. Unfortunately that Genesis had to be scrapped because it was unsalvageable.

Still, in the end, I got it working and I must say, the difference in picture quality is quite remarkable.

PS:


If you can, but a more fine conical tip. That combined with a third hand made modding it easy. Keep in mind, I did this with the help from a friend and a $5 soldering iron from Wal-Mart (found in the automotive electronics section oddly enough).

Thanks a ton for the detailed response! I was under the false impression that the Genesis 2 used the same chip as the Genesis 1. That link you posted was the one I was referring to when I noticed how easy the mod would be (besides the tiny leads on the chip). I may just have to crack open that Genesis 2 tomorrow and have a look, I'm pretty sure I have all the components I need for either mod besides the S-Video connectors, I hope Radio Shack doesn't want too much for them .

Although the Genesis 1 hack while requiring slightly more parts is still a very simple circuit and I wouldn't risk ruining the system with such a large chip to solder onto. I'll definitely have to buy a new smaller tip for my el cheapo soldering iron.

I'll post my results back here, I'm always excited about a new project.

[b1aCkDeA7h]

...I was under the false impression that the Genesis 2 used the same chip as the Genesis 1... the S-Video connectors, I hope Radio Shack doesn't want too much for them...

I think in some cases, the Genesis 2 does have the same chip as the 1, but perhaps a smaller version of it. Someone else might be able to confirm this as I'm not entirely sure. Also keep in mind that I started this topic to figure out a way to determine which Genesis 2 systems have the super easy to mod Sony CXA1645M chip inside. So far, off of three examples, I seem to have found that they're in Genesis 2 systems with the Model Number of MK-1631A. A phillips head and about 5 minutes will confirm this.

As for the female S-Video coupler, I think Radio Shack sells them for $6 for the S-Video coupler alone or $12 for a set of S-Video and RCA Couplers. I know the $6 one was housed in metal while the one in the $12 set was housed in plastic, which proved to be quite easy to cut in half. Hopefully the metal housed S-Video coupler is the same as the plastic housed one in that its just the female S-Video ports soldered to a small passthrough board.

[crrimson]

Turns out my Genesis 2 has the SKA chip.
Model Number: MK-1631
Serial Number: AD42053478
Made in Indonesia

I may just mod the Genesis 3, but I never liked it quite as much as the 1 and 2, it just looks and feels cheap to me compared to the older models.

[b1aCkDeA7h]

Turns out my Genesis 2 has the SKA chip.
Model Number: MK-1631
Serial Number: AD42053478
Made in Indonesia

I may just mod the Genesis 3, but I never liked it quite as much as the 1 and 2, it just looks and feels cheap to me compared to the older models.

A shame. If you have any local classic game stores, see if you can swap yours with one that has the CXA1645M inside. Failing that, my friend got one a model 2 with the CXA1645M for $8 at a thrift store, the lucky bastard. Last time I was at a flea market, I found a MK-1631A but since I wasn't looking for that on my visit, I didn't bother.

[crrimson]

Yeah, I think I got my Genesis3 for about $6 at a goodwill, and my Genesis 2 out of someones trash! However, all the older systems have been increasingly hard to find at thrift stores, and if you do find them the prices have gone up. I will look around though for sure and post back if I find one or decide to mod the genesis 3.

[b1aCkDeA7h]

Yeah, I think I got my Genesis3 for about $6 at a goodwill, and my Genesis 2 out of someones trash! However, all the older systems have been increasingly hard to find at thrift stores, and if you do find them the prices have gone up. I will look around though for sure and post back if I find one or decide to mod the genesis 3.

Actually yeah, my local thrift stores are jacking up prices so I know what you mean. Flea markets are still viable it seems.

[crrimson]

I decided to test it out on my Genesis 3, so for the S-Video connector, I desoldered one from an old broken motherboard I had, grinded my soldering iron tip down to a point so I could work with the tiny pins on the CXA1645M, and gave it a test run without mounting the S-Video connector in the case yet, and the video looked crystal clear! It was excellent.

I realized I didn't have any 75 ohm resistors either, so I used 2 150 ohm resistors in parallel for the both the Y and the C pins.

Now the big problem is going to be figuring out how to mount that S-Video connector in this tiny little Genesis 3.

*Edit, I got it mounted and it works pretty good, I had to cut away some of the RF shield, and it's mounted on the right side of the system because there was no room on the left by the other cables.

[knight63]

MK1631A Serial #252146449. Just getting ready to list it on EBAY