My latest pickup, and something I’ve been on the lookout for a while (as always at not stupid B.I.N Pricing) is an Atomiswave system by Sammy. This is the cheaper, slightly less powerfull version of the Sega Naomi (i.e. less RAM). This actually came out AFTER the NAOMI 1 and NAOMI 2 systems just as arcades started going downhill again in the early-mid 2000’s. Basically a Dreamcast in arcade clothing that runs on JAMMA (with VGA output) so it has great compatibility with old and newer arcade cabs and I’m guessing this was kinda the point given when it was released.
The system itself is in rather good shape (certainly better shape than the abused NAOMI systems you always see). Howerver, this has two holes drilled in the side of the system so it looks like someone has done, or tried to do, a stereo Mod at some point. Will be interesting to see if this is a hack job mod or if any remnents still even exist.
So, time to take it apart and see what we can find inside. Removing the plastic covers for the expansion ports (used for things like inter cab communications board and the gun controller I.O board) reveals 6 screws that help secure the top plate of the case to the main chassis. Remove these first.
Now, on the front edge of the case, there’s a retaining screw in between the JAMMA edge connector (totally standard) and the remaining I/O ports on the right. These are the DIP switches (for setting test mode and 15/31Khz modes), the volume wheel, a connector (CN3) that is for Stereo sound output via an adapter (that I don’t have), the VGA output and a serial port. It should be noted that, as long as the monitor you’re running through can accept 31Khz via it’s Non-VGA connector you don’t NEED to plug in a VGA cable to use 31Khz mode It will output 31Khz over the JAMMA edge.
This is a close up of the DIP Switches. There are a little stranger then most I’ve come across as they ‘seem’ to operate in the opposite direction to how I think they should. ‘On’ is flicking them DOWN and AWAY from theswitch housing (arrow shown).
Flipping the case around reveals one final retaining screw and the FAN exhaust port. Thankfully this is not as noisy as the NAOMI boards (I know I keep making the comparison but they really are so similar…). It makes an audible hum, sure, but with game audio simply ‘on’ it’s not really noticable.
Turning the case over reveals nothing…. this seems to be the main plate everything inside is mounted to (see the copper Motherboard standoffs visible and some venting holes).
So, the red top cover will now lift and slide off the rest of the case (up from the back and then slide over the JAMMA edge). Doing this reveals a mettal Shield protecting the motherboard. Undo the 5 shown screws and unplug the fan in the top left. This loosens the plate but it can’t yet be removed due to the small PCB in the bottom right stopping the plate from coming off.
Here’s a close up of the part that needs to be removed in order to proceed. It’s the board containing the volume control and Serial connector. The serial connector port binding posts (Shown) will unscrew by hand if loosened with a set of pliers (just grip and turn counter-clockwise).
The only thing stopping this board being removed now is this small plasticclip (left side of board). This holds the board securly in place but, as it’s plastic, could be brittle. Carefully compress the clip part and you should be able to simply pull the board up and off the plastic post.
This is the removed board. A serial port and a variable resistor fo the sound. The wire connector pulls out easily, there’s no locking clip and it’s keyed so it can’t be put back incorrectly.
Now this board is removed we can see the area on the main PCB where the legs of the ‘CN3’ connector push through. This is the stereo sound connector and shows where a previous owner has attempted to put a stereo RCA mod on to the board. Clearly they have given up as this is all that remains of the attempt (outside of the holes on the outer case). The idea would have been to solder wires to the L, R and Ground pins here and then attach them to RCA plugs on the case. Thankfully, the remnants of this attempt came off really easily.
The main board has a VGA connector with the same retention screws holding it to the case. Same as before, unscrew to continue.
More screws next with another 4 screws holding the motherboard to the chassis. The top two are threaded slightly differently so ensure you know which screw goes where.
And now it should be possible to remove the motherboard from the chassis… but it isn’t… it turns out that the design of the Atomiswave includes an integrated heatsink. But, in this case the CPU and GPU are thermally glued (via adhesive pads) to a metal heat spreaderitself attached to the chassis. Great for keeping the costs down and the heat at bay but rubbish for teardown and curious people. I could technically remove this with a bit of heat and a spludger but i’ve not got any replacement pads and I do want to use the system. So, lets just look around as best we can without removing the board from the chassis.
The actual design is interesting. Heat from the GPU and CPU transfer to the metal heat spreader. This is hollow and attached to the chassis backplate. It’s also orientated that the exhaust fan pulls air through the gap cooling the system as it goes (direction shownvia arrow). I like this. Very efficient!
Looking through from the other side we cn see the backup area for the score saving / book keeping battery. This looks like a standard rechargable Lithium button cell battery. Happily this has sealed edges so 20 years down the lineit shouldn’t leak and kill the board (unlike every MVS system ever).
Next up to the right is another integrated heat sink which looks like the audio amplifier as it’s connected to the ribbon cable that connects to the variable resistor on the sound control board.
And thats about it for interesting things that can be seen without taking the whole board away from the heatsink. Now to put it together and go play a game 🙂