Sega Mega-Tech Restoration

[mourix]

Been more active on UKVAC lately but let's not forget this forum we all grew up with. I present you this original Sega Mega-Tech

Up front, things are just your basic 30 years of wear and tear. Gotta replace locks, CPO, buttons and clean a whole bunch:



Up back and around, things are not as nice..The rear door is missing, and the backpanel is severely kicked in. Additionally, the bottom plate also has a crack so the entire cab is wobbly. I'm on the fence whether to stabilize the backpanel or make a new one entirely:



When I picked up this machine I immediately noticed the main monitor was not original. There should be two Hantarex MTC9000's in there, but the main screen is a Kortek KTM-F. After sliding down the cab from the second floor we found this green connector on the floor. Later at my home the main screen did not light at all. You know why? I figured out the green connector is the AC in for the original MTC9000, and the red and white wires are the AC in on the Kortek. I definitely want to improve this. For now, it literally just had to be shoved in there:



So that leaves me with this:



Electrical inspection time:
The main board works with all 8 original games.
The sound is really tinny. Maybe a main board recap needed.
The power supply -12V line measures -16V.
The menu screen is very sharp but way too bright.
The main screen is quite blurry. Not sure if that's dirt or focus. Also the adjustment board of it had a broken pot.
Finally, all lamps are missing....

I've got big plans for this machine. At the end of the run, it will be almost like new.
As a hardware engineer, I also want to design some custom game carts for it. This time open source for everyone

To be continued...
 

[mourix]

Mini update.

Ordered all the light bulbs and locks. Also, I found out why the monitor was so blurry:

[mourix]

Lights came in:



I also adjusted both monitors. Things are looking pretty great in a dimly lit room:

[pbj]

Never saw one of these in the wild, pretty cool looking.  Looks like the cartridges are pretty easy to bootleg:

https://www.tindie.com/products/caiusarcade/sega-mega-tech-reproduction-cart-blank-board/

Surely other games have been ported to that system by now?

EDIT - looks like you can run an Everdrive on them...

https://mega.nz/folder/5mZGTQZQ#mDAuPaSu1BSt6G0WRXTMqQ

[Mike A]

That thing looks cool.

I am not familiar with it.

Thank you for posting.

[mourix]

Never saw one of these in the wild, pretty cool looking.  Looks like the cartridges are pretty easy to bootleg:

https://www.tindie.com/products/caiusarcade/sega-mega-tech-reproduction-cart-blank-board/

Surely other games have been ported to that system by now?

EDIT - looks like you can run an Everdrive on them...

https://mega.nz/folder/5mZGTQZQ#mDAuPaSu1BSt6G0WRXTMqQ

The Mega-Tech did not get a wide US release.

I got many open source hardware ideas brewing. There are Mega Drive or SMS based original carts to be remade ofc. But even a Mega-Tech to original Mega Drive or Master System cart converter board should be possible

Right now I'm trying to get all the data on the Arcade Otaku wiki. Lots of reverse engineering to do.

[mourix]

This weekend I stabilized the foundation. Basically the entire side was cracked and wobbly:



I hid 6 long screws below the metal protection bars along the bottom. For good measure I put some extra metal braces, long screws for the feet and lots of wood glue. This is now most definitely the strongest section of the entire cab:

[Mike A]

Keep it coming.

Love it.

[mourix]

Documentation sharing time

The cab included a written manual for the Hantarex MTC9000, but the changed main screen was a Kortek KTM-F with no manual available online.
I ended up tracking down the missing manual on UK ebay. Damn, post brexit import duties and shipping cost were higher than the item...

Anyways, here we are:



After a night of scanning and Photoshop now free for everyone:
Kortek Sejoo KTM-F Technical Manual Eurocoin Vision Series
Hantarex MTC 9000 Service Manual 14"-20"
Hantarex MTC9000/A Circuit Diagram 14"-20"

[mourix]

I got many open source hardware ideas brewing. There are Mega Drive or SMS based original carts to be remade ofc. But even a Mega-Tech to original Mega Drive or Master System cart converter board should be possible

Right now I'm trying to get all the data on the Arcade Otaku wiki. Lots of reverse engineering to do.

Sneak peek at what's (home)brewing:

[mourix]

Front kickplate cleaned up well after some magic eraser and black permanent marker action. Also added new locks, screws and obligatory Sonic keychain.



The Dutch regulatory sticker plexiglass was cracked up pretty bad. To keep it stock, I just 3D printed some washers to hide most of the damage.

[mourix]

Currently I have reverse engineered both the Megadrive and Master System based carts. These are on the way from China as we speak:



I'll do a full write up once I got them in and tested. The plan is a Github for everyone to make their own.

[mourix]

In today's update: a warning for people wanting to recap the Mega-Tech PCB.

I wanted to try a recap because my cab sounded like a smartphone. So I made the cap list here and got to work.

I own a decent soldering/desoldering station so usually it's a breeze, but not this time. This board got all the difficulties.. Multilayer ground planes, small through holes, bent leads and thin traces right next to cap pads.

After hours of soldering it does look nice though:



However this is what I was greeted with when I plugged it in. Crapp.. Back to debugging I guess.



NES4Life has a nice write up on this so I knew which area to look at. Finally found the issue:



I added one blue botch wire to the green factory botch wire seas:



But hey, we are back!



But... now the left speaker was dead. After a bunch of digging that was a 3mm track without a connection so a solder blob got it back.

And now I own a nicely recapped Mega-Tech that almost killed it...and still sounds like a smartphone. I guess it was 80's speaker quality all along

[mourix]

Progress update on the homebrew. I want more games in my collection, but even sports ones are getting expensive now. There are some guys selling repro gamecart PCBs, but I want open source everything

For the whole library, we need both a Mega Drive and Master System based cart. The 171-5782 is the common 4M Mega Drive cart, and the 171-5783 is the common 1M/2M Master System cart. 

To get both, these were the sport game victims of the day:



After taking them apart and removing every component, I made scans of both sides of both boards and lined them up in Photoshop.



Based on those master Photoshop files, I traced every track in Altium Designer software until I had an almost 1:1 reproduction of the layout and schematics to accompany.



After lots of tidying up I ordered 10 pieces each from JLCPB. This showed up yesterday:

[mourix]

The Sega Mega-Tech is pretty much a Mega Drive glued to an additional Master System that runs the menu screen. To make this duo work, the (same as home version) game rom is placed on a circuit board with an additional custom menu rom that contains the text to fill the menu pages.

The menu rom is a 27C256 that can be had from Aliexpress for cheap. So cheap even that my newly acquired T48 programmer freaked out because the Chip ID on them did not match the painted on manufacturer name.. But I got 3 out of 4 programmed in the end.



For the 4M Mega Drive games, a 27C400 EPROM fits in without modifications. But with me owning like 5 copies of Sonic 1, I just desoldered an original game cart chip.



I put it in the cab and was greeted with the following. YESSSSSSSS!!!!

[mourix]

The Master System cart is a bit more complicated than the Mega Drive. The menu rom is the same 27C256, but the games themselves have special roms with built in mapper logic. This means the only easy way to make a repro is to remove a rom from an original Master System game as eproms won't work.

Hence, the game rom stealing continued:



But the results continued too



There is still one mystery left. The original Mega-Tech cart has connections to ground a bunch of rom pins, but the traces are strategically drilled out on the 1M rom cart I had. Interestingly enough they also exist and are drilled out on the 2M Master System console games I own. I've experimented a bit with a cheap sports game rom and it has the same power consumption and behavior no matter if the ground connections existed or not... Does anyone have an idea about this, or is someone able to open up a 2M Mega-Tech cart to verify?



I definitely have some more game making and experimenting to do.

Once I am 100% confident on the design I will make a Github release and forum thread

[mourix]

The Mega-Tech carts are housed in Japanese Mega Drive shells. To make the repros complete I got this from Aliexpress:



To make it fit, some small studs in these shells had to be cut and the DIP sockets removed. But after putting it in, something was off. It was like the edge connector is too short.



To make sure, I opened the original soccer cart back up. Yup, too short.



But now I put my repro in the original shell. See? My cart is correct:



So now I am in need of input. Do we adjust the PCB design release for these crappy shells? I am a tad unsure.

[mourix]

Control panel time.

This is the starting point. Cracked/faded CPO with very crunchy buttons. Definitely needed a refresh.



Now to continue the insane open source project, I got another Canon Lide 110 for €3,50 and followed my own tutorial again.
I put together the scans and made my own reproduction. This came in a week later:



Finally I put the CPO on together with legit IL PSL-H pushbuttons and Cherry D44X switches I had to import from France as Dutch stores only sell Ali imports..
Disassembly was a paint with lock nuts, glued buttons amounts of CPO glue that should be illegal. The results do speak for themselves though



The 300DPI print file is attached below.

[mourix]

With another Master System game butchered, I also added Fantasy Zone to the working collection. That means both 1Meg and 2Meg games are verified now!



As for what's to come

Improved "Redux" versions.


Home console converters.

[mourix]

Just placed an order for the 4 shown PCB designs on JLCPCB. Let the two weeks of impatience begin

I also found the source of the audio issue: one speaker was wired in reverse polarity...

I'll still replace the speakers but at least it now sounds basic instead of rediculous.

[mourix]

How to make replacement back door, the legit way.

Like seriously, guys. Why does everyone use painted MDF? Late 80's+ machines are pretty much all dual side laminated chipboard for good reasons. /rant

So for the Mega-Tech you need:

• 30mm length cam lock.
• 40x60x2mm steel connecting plates.
• 18mm black laminate chipboard, cut to 59,7x52cm.
• Authentic finger prints all over as black laminate does..

Assemble it like this:



Be in awe at the legitness:



And then push your machine back to the wall and never look at it again

[Mike A]

Love it.

[mourix]

Love it.

Thanks, Mike

[mourix]

PCBs came in

Starting with the (to be open sourced) Mega Drive converter!

Before I start I have to give full credit to Nipedley. This person has done an incredible amount of research back in the ~2010 era and used to have his own site that is linked to on several blog posts of the time. Anyway, he posted his magnum opus on this random forum post from 2017 and then seemingly disappeared from the face of the internet.

He went out with a bang, though. Turns out that this random Mega file of the pre covid era contained gold. It has recreated artwork, scans, manuals, info for making custom menu roms, and a complete reverse engineered pinout of the Mega-Tech cart slot with full comparison to the Mega Drive and even instructions to get an Everdrive going.

So I fired up Altium and designed a board to his spec:



I then fired it up and magic happened:



My bonus reverse engineering efforts for icons in the menu paid off too:



I then got overconfident and tried my Master System converter, but that one unfortunately needs debugging I will get to in a future update...

[pbj]

Incredible work.  Have you considered simply…. Cutting down your mega drive shells for those pcbs that don’t have long enough fingers?  It’s not like children are ever going to be banging around these things.

 

[mourix]

Incredible work.  Have you considered simply…. Cutting down your mega drive shells for those pcbs that don’t have long enough fingers?  It’s not like children are ever going to be banging around these things.

 

Thank you. The limit on these shells is not the end perimiter, but the "wall" the edge slides through. I ended up making the new carts 1mm longer.

[mourix]

Compilation carts.

So turns out Sega made a bunch of 3-6 game compilation carts near the end of the Mega Drive's life cycle.



Let's find the best combination:



After which, I made python script to generate menus for many custom carts:



For the next step, get scammed on Aliexpress by getting 1 27C322 instead of 10:



After getting a refund and getting more, make these carts:



And suddenly the menu is on the Mega-Tech:



And Gunstar Heroes plays



With these 1mm longer Redux carts, the fake shells are fine.

[pbj]

There's also a "10 in 1" ROM that combines most of those multis into one.  It does take a little while to boot on my system... like 5 seconds or so.  No big deal, but it's unusual.

[mourix]

The Mega-Tech has the menu rom mapped at 3MB. So that's the limit of size it stabally plays. The 10 in one is 4mb.. But the ones I show top out at 3mb.

[mourix]

Got the master system roms permanently transplanted to the redux PCBs too.



Legit bootleggery here

[mourix]

With the repro carts now being stable, I've open sourced the designs with a support thread here.

[mourix]

Stabilizing the cab even more...

I wonder what the heck happened to this thing because so many more pieces turned out to be loose. Did it fall down the stairs or something?

Just look at the back:



I had to get it straight and put screws down the top.



Followed by angle brackets on the rear top.



At least that sorted out the back.



But the cab was still wobbly even after my previous fix. Oh, the other side was trembling apart too, just not cracked on the bottom.



Followed that by another hardware session:



I think at this point that only really leaves the side art and missing wood chunks. Of course I'll remake the sideart, but I'm thinking of patching in some black laminate squares to the damaged parts.

It would not be perfect, but at least it won't look as bad as paint?

[mourix]

Mega-Tech - Mega Drive Converter Release

It's here!

Just for a reference, I tested the following random games off my shelf today:



They all worked flawless besides of Ecco TOT giving a PAL region error, but I won't call that a bug.

So to let you guys in, this whole Mega-Tech PCB project was something I took on whilst being in between jobs to not get too bored at home.

Fortunately I will start new work in May so this thread will go back to regular speed from now. It was fun while it lasted though