Overhauling the Sega Astro City – Part 2, audio amplification and fans

No Comments »

I’ve already got the ball rolling in part 1 of this series, so let’s move on to part 2 – audio amplification and fans.

In line with the previous post, I want to add a way to have a stereo amp in the cabinet to take care of line-level sources and enhanced stereo sound (e.g. Naomi, CPS-II, Sega Model 3, etc). So, in the spirit of making the cab as universal as possible, I need to look at adding in a small amp that can be switched on or off as required, and be able to direct either amplified sound off the JAMMA cable or amplified stereo output as required. So, this is what I’ve come up with:

It’s not all the difficult – I’ll need to rewire the 4-pin connector that goes from the speakers at the top of the cab so that they’re separated into stereo channels, then create a little switch to roll between a split dual-mono amplified output (from the JAMMA harness) or stereo output from the stereo amp, which in turn is powered off a 12v source (with switch to control when it’s on) and grabs its input directly from the PCB (Naomi, Model 2, etc).

This then means the audio can be setup in the cab when inserting a new board. All I’ll need are a pair of stereo RCA cables to run form the CPS-II or Naomi boards (and make a stereo RCA adapter for the Model 2/Model 3 boards) and run them off a pair of 12v mono amps I already have around the place, and I should be good to go.

The other addition I’d like to add is a stereo controller I can mount on the cab to adjust the output before it goes to the speakers as required – there’s currently a cheap knob the previous op added to give this kind of functionality, but it’s not a true stereo actuator, and doesn’t do much except distort the audio

Of course, the great thing with this setup is that it won’t cost much at all to add this kind of functionality. To make it clean though, I’ll plonk the lot into a small project box and mount everything inside it. This way, I can use the same project box to run a 12v switch to selectively power the 12v fan I got with my Model 3 kit before. And to make sure I don’t mangle my hand again, I’ll also grab a pair of 120mm fan guards to avoid any more stupidity

Thus ends part 2 – part 3 will deal with the lovely scope creep and deciding what to do with my monitor

To keep track of the whole project, just use the Sega Astro City Overhaul tag – the whole series will be added to it over time.

Overhauling the Sega Astro City – Part 1, power supplies

No Comments »

I’ve been meaning to write something up on this long-winded project for a while now, so here I go – not sure how many parts there’ll be to this job, so we’ll just have to wait and see

I’ve recently been looking at the existing setup inside my Astro, and can’t help but feel that it needs some work. The wiring is a bit of a rat’s next at times, I don’t know where all the cabling’s going, I’ve had to beef up to wiring on the 5v connections to increase the PSU’s output, the PSU itself is on the way out, as is the existing arcade monitor.

Where things got to a bit of a head was with regards to power issues – I’ve recently grabbed a Naomi and currently have a couple of Model 2 and Model 3 boards that need a reasonable amount of juice on tap. So, I figured that maybe I should investigate rewiring the way the power supply worked. The problem here was finding a power supply that couple happily take everything from a mid-80s PCB all the way through to resource-hungry Model 3 and Naomi setups. This left me with two options:

Option 1 – Parallel PSUs

In this case, I’m taking the 240v AC supply, chaining it across my existing 15A arcade PSU, chaining it to another 15A PSU and finally chaining it to a 3.3v PSU I bought a while back. From here, I then wire it to a distribution block, which connect to suit Naomi, Model 2/3 or JAMMA.

The pros with this is that all I need is another PSU (cheap and accessible), it runs off 240v (no need to run it through the transformer), and doesn’t require too much tomfoolery.

However, against this is – will it actually work on games that need a full load? What if one fails? Is it really safe to be mixing too PSUs together to get this kind of power distribution.

This then leads to option 2:

Option 2 – Dedicated PSU

In this case, the aim is to grab a Sega Sun power supply, since they are great pieces of kit and are certified to power anything you can throw at them.

There are some challenges with this – cost (they’re more expensive and more difficult to get locally), only 110v (therefore would require some extra work on hooking it into the transformer), no -5v output.

In the end though, I decided to go for the above setup – fork out the extra for the PSU, grab a Negatron to introduce a true -5v connection where necessary for older boards, and run them all off a distribution block.

However, after chatting with some more experienced arcade builders, I decided to change the model a little – instead of having a big distribution block, I decided to simply create a handful of male JST plugs for each connection (e.g. JAMMA, Model 2/3 and use standard cabling for the Naomi) and hook them directly into the JST power plugs on the PSU. The following is the final run:

So, I figured if I was going to start rewiring some areas of the cabinet to accomodate the PSU and make the whole setup more universal, there are two other factors to consider – amplification for line-level sources and getting the 12v fan from the Model 3 setup up and running when needed – you’ll see these (as well as switches to accomodate them and the Negatron when needed) have been added to the above diagram.

But I’ll stop here before I get too carried away – part 2 will deal with more of the planning behind this project.

To keep track of the whole project, just use the Sega Astro City Overhaul tag – the whole series will be added to it over time.

Update on power supply problems with Virtua Fighter 3 (Model 3) PCB

2 Comments »

Finally have an update on the power supply problems I’ve been having with my Virtua Fighter 2 and Virtua Fighter 3 respective Model 2A and Model 3 boards.

After tracking down an eBay sale of a Model 3-fitted and ready PSU, I buckled, bought it, and it finally arrived yesterday. I gave it a preliminary run to see if I could get the thing to power up, and it looks like we may just be in business

The setup’s nothing too refined, but is startlingly effective – it’s basically a standard ATX power supply running on 240v with the 12v, +5v, +3.3v and GND going to a couple of distributors on a block of wood, and the distributors rope around to the various connectors on the board. The input and video run back to a JAMMA biscuit, and the sound (not connected) has been wired to a 4-pin molex connector, but currently doesn’t have an amp fitted.

Moving forward, from here I’ll need to take the Wei Ya audio amp off the existing Model 3 >> JAMMA adapter I have and fit that into the loop and connect it up to the JAMMA biscuit to get sound going through. Will have to look at doing something similar for my Model 2 board as well, might see if there’s a way I can quickly hook up the PSU to my Model 2A filterboard to at least test the thing and see if I can get the sucker powering up.

The funny thing with all this is that Wifey said ages ago that I should have gone out and grabbed a big beefy power supply for the system before messing around with everything else I’ve done. Looks like she was right all along

Once I’ve had a chance to properly connect the whole shebang together and get it up and running, I’ll post up some pics to share. Might also prove useful to other people interested in doing similar mods on their systems.

Virtua Fighter 2 (Model 2) and Virtua Fighter 3 (Model 3) booting and power supply (PSU) problems

1 Comment »

I’ve posted this in a few forums, so thought I’d track it on my blog as well. The following’s a slightly edited version of my post

A few months back I snapped up VF2 and VF3 from someone interstate, and have been having some troubles with them, and I’m not sure if it’s me, the boards, or maybe a combination of both!

Now, before I go on I’ll clarify my setup – Astro City cab with a 15k/24k chassis (Pentranic, previous owner slapped in a generic 15k chassis that blew up, so I replaced with a Pentranic), bog-standard Peter Chou 15A PSU, 3.3v Wei-Ya PSU, cab is JAMMA-ready. To connect the Model 2 and Model 3 boards into my JAMMA setup, I’m using one of these (Model 2) and one of these (Model 3).

In order to boost the 5v and GND lines on the main PSU, I’ve also increased the amount of wires coming between the PSU and the JAMMA connector as I wasn’t getting solid +5v due to some flimsy wiring. After beefing up both lines, I’m getting much better performance across all my PCBs (CPS-I, Neo Geo, CPS-II, System 11 and a few others).

I’ll start with VF2 – I’ll put the chassis into 24k mode, roll the PSU back, connect VF2 and get the voltage to 5v (maybe 0.05v over). On the PCB, the red LED 11 is lighted up, and I’m getting like a garbled green test pattern thing on the screen. I’ve pulled the PCBs apart and put them back together again, checked to make everything’s in there nice and tight and checked for physical problems on the boards, everything checked out, no change. To test things a bit further, I removed the top ROM PCB, leaving the bottom two boards (since it’s a Model 2A system, it’s a platter of three boards) and rebooted – same problem, LED 11 is lit up, I think I saw a couple of red LEDs on the bottom board near the filter board light up, and the garbled screen. Turned off, put the ROM board back on, the LEDs on the bottom board are fine, but the red LED 11 in the middle board is still lit up. Garbled test pattern remains.

With VF3, it’s a bit more tricky, and I have a feeling it’s my PSU that’s to blame here, as well as some of my wiring before I beefed up the 5v and GND lines. With VF3 when I first tried booting it a month or two back, the 3.3v PSU worked a treat, but the old Peter Chou would crash out immediately – the red light to indicate it was on would light up, then immediately drop out and there’d be no power on the JAMMA adapter when I tested it with my multimeter. I figured my PSU might have been on the way out, so got a new standard arcade PSU (a 16A Min Dong), connected it up and had success… or at least I thought I did. I measured at the JAMMA adapter and it wasn’t getting to even +2v on the +5v line; I cranked it, barely got to +2v and the JAMMA adapter was getting really hot. Next thing I knew, it smelt like the PSU was overheating and the little light indicating it was on turned off. The new PSU went and died on me Disappointed, I reconnected the old Peter Chou PSU. I noticed a couple of red LED lights come on when I power up the Model 3 off the Peter Chou (even though ti conks out) and the 3.3v Wei-Ya (which I’m going to take as meaning the Wei Ya is working fine, since it doesn’t conk out), if that helps. Another thing I noticed is that how much success I have before the Peter Chou PSU gives up depends on the amount of +5v/GND connections – I can have the 5v and GND connections on, say, JST CN13, and it won’t kill the PSU, but if I hook up JST CN14 as well, the PSU dies. Does this help?

I was talking a few other people with more experience than I have with arcade cabs, and they mentioned that the fact the JAMMA adapter was heating up indicated there wasn’t enough copper between the PSU and the JAMMA adapter on the +5v and possibly the GND connection as well, and suggested beefing up the wiring to fix that part. I’ve done that and am getting better results when playing the rest of my games, and when I tried loading VF2 or VF3 with the beefed up wiring, VF2 still gave that garbled green test pattern screen thingie (red LED 11 still on), and VF3 still died off. They also mentioned the red LEDs might be indicating a fault with the board or power supply.

I’m a bit stumped with what I can do to fix up these issues – I’m a huge VF fan, and these two games were part of the reason I wanted to get my own arcade cab. I know there are some very clued up Model 2 and Model 3 people on these forums, but couldn’t find anything that coped with these problems. I’m not sure if it’s a PCB, PSU or even jumper settings issue that’s affecting my PCBs. Some other people I’ve spoken to who run Model 2 boards have done it consistently off standard arcade PSUs for years, but they emphasise that you need to ensure your +5v and GND connections need to be extremely strong in order to do so.