Defender is a great game, one of the hardest out there. Many people find it too hard, while the ones that master it seem godly when they play.
Congrats! You're about to level up in your arcade hobby! Building mame-machines is the easy stuff, but maintaining original hardware is a whole different beast. Don't be discouraged, you'll end up learning a lot of things about arcade hardware that you probably wouldn't be exposed to building just mame cabs.
Like drventure says, here at BYOAC mame projects are more common, KLOV is your best bet for more in-depth info and help. But, there are the few of us who frequent both, and have experience fixing/restoring originals, so it's good to get more coverage IMO.
So, the problem is, it powers up but shows the error message: "Initial test indicate RAM failure." I did some googling and forum searching and it seems this is a fairly fixable thing, but the troubleshooting procedures enter all sorts of realms beyond my comfort zone. Checking voltage levels, not getting electrocuted, etc etc. I am very experienced working with computers, but this is something entirely different!
Unfortunately the nature of the beast will get you to do uncomfortable tasks that you're not experienced with. Don't fret! You're going to learn a lot, and in the end it'll make you a stronger hobbyist. RAM failure is a very common problem on these Williams machines. The very first thing to do is to get your hands on the manual and schematics and have a read-through. This is mainly to get you familiar with the parts, as well as some of the testing procedures, plus it's great to have as reference if you need to really dig deep.
The RAM failure message doesn't have that much info on screen, so you'll need to get into the back of the cabinet to see what the LED codes are saying. I.e. What ram bank is the problem. If the error is the first chip in the bank, it's most likely you have a voltage problem. But if it's a chip that isn't the first, it could be faulty, and require replacing. Definitely checking voltages coming out of the power supply is going something you should do. Do you own a multimeter? They're cheap, and you'll have to get one.
Also, how is your soldering ability? If you have to replace a RAM, you'll end up having to get your hands dirty regarding soldering.
In searching around, I found this (link). Is this thing still available? Does it essentially "bypass" the orignal boards? If so, seems like this would be the ticket....if the original boards can't be fixed by something simple like cleaning/re-seating the chips...
http://www.jrok.com/hardware/wsf/
It's unlikely it's just a "reseat" issue. The best you can hope for is that the connectors aren't making proper contact, and could be reseated, but I'm not confident that'll fix it.
There could be a few things you can check for, if the power isn't putting out the right voltage you'll probably need to recap it (requiring soldering). If the voltage is right, then it could be due to the connection headers being degraded over the years -- cracked solder joints, this was one of the issues in my Robotron cabinet, those headers are cheap and are prone to failure (replacing them requires soldering). It could even be the RAM chip itself, as stated by the LED error message inside the cabinet.
Jrok boards are not in production anymore, and are a bit harder to find. If you do find one, they go for around the $300 mark. There was a post by James (JRok) himself recently that stated he was going to make another run sometime this year, so you might be able to wait for that. But still, if you have bad voltages, then you're still at square 1.
What might I be getting myself into? What else should I look out for? What's a fair valuation of a machine with this issue? Should I just forget it and stick with MAME projects??
I've seen non-working machines go for around $250-300.
If this is your grail, I think it's a great way of diving into hardware repair, 'cause you'll be more passionate about it. But you'll have to man-up, and get into the big-boy pants and be prepared to read a lot and learn a lot. Like I said, Mame machines are EZ-mode, this is a more complicated beast.
There are great resources to get started on the net.
AO has a nice wiki page regarding general board repair. They tend to deal with JAMMA boards more often than not, but it's a neat primer:
http://wiki.arcadeotaku.com/w/Game_Board_RepairBob Roberts has a lot of great general information on his site (I frequent it a lot)
http://www.therealbobroberts.net/helppage.htmlThen of course, there's KLOV which has a very robust amount of Williams tech info and repair posts. Getting acquainted with their search engine is something you definitely need to do. This will probably be your #1 resource.
If you can get a digital copy of the Atari The Book (red cover), it's also a good primer on general repair, it definitely won't make you a repair tech, but there's good beginner's information there to draw from.
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Topic: Found a nice Defender - would be my first attempt at a restoration (Read 3032 times)
