Williams
These are some tips for repairing old Williams like stargate, defender, robotron, joust, etc...
Ok let me do my disclaimer...This is not necessarily whats wrong with your game so dont blame me if you mess things up, these are just things that fixed some common problems with my games and I urge you to read the whole thing. This is for people with some electronics skills, if you dont know how to solder and read a voltmeter then send your board for repairs.... Ok that being said here we go
1-3-1 Ram Errors
1st- Check your 4116 ram chips, not just one of em, all of them. Ive had bad ram in different locations all causing the same 1-3-1 error. Try swapping them around if you dont have extras and see if the error code changes.
2nd- Check your power. Every williams game made needs the solder on the power supply board reflowed. You should check your power at different points on the cpu board. You must have +5, -5, +12 for the cpu board to work properly. Sometimes the +5 volts will dip below whats needed for board to function properly and give you a reset(this can be random). There is also the possibility of bad ic sockets that hold your ram chips. I would look for all 3 voltages at your 4116 ram chips. For example, I have a joust board that the 8th bank on row 3 was only getting 3.5 volts. I replaced the socket and it booted right up. Its a good idea in general to check your voltages around the game to go ahead and head off problems before you go jerking chips off the board and burning eproms. I learned that the hard way. I am told that new switching power supplies give fewer 1-3-1 errors. See the power supply section below for more info.
3rd- Check the ribbon cable. I have seen ribbon cables cause all kinds of problems. If you are having crazy numbers on your led check your ribbon.
4rd- This is not as common of a problem but one I have faced. Sometimes the 74153 located at position 3d will go out.(I actually couldnt see any fault with this chip using the logic probe at first but after letting the game sit a few minutes I started to see errors). This causes 1-3-1. Replace the chip.
Random Resets
1st- Check your ram and your power-see the 1st and 2nd steps in the 1-3-1 ram error section above.
2nd-I was having very random resets during play and it would happen mostly in the heat of battle. I popped in a new 6809 cpu and the problem disappeared.
Adjustment Mode Failure(at boot screen)
1st- Check your batteries. You should investigate where your batteries go. A lot of Williams games were stored with batteries in them causing massive corrosion :(
Its really a good idea to convert it to the lithium battery modification. Its a better solution than AA batteries and will possibly get rid of the adjustment mode failure problem associated with new switching power supplies. Ive had people tell me it doesnt help and people tell me it fixed the problem. I have only seen it work not fail.(For more info see the power supply section below).
2nd-This problem seems to be fairly common and is related to the ability of the machine to keep settings while powered down. I know what your thinking..."I just put new batteries in it".... LOL-We wish it was that simple dont we. I tracked this down to a bad cmos ram chip at location 1c. Replaced the chip and the problem vanished.
Rom Board Errors
1st-Verify your eproms with a know good set.(You must have an eprom programmer to do this) You can download the mame rom sets and use them.
2nd- IC sockets. Find these by checking your voltages on the board. Must be +5 volts and ground coming in to the board.
3rd- Check the traces. Especially the ones running from rom to rom.
New Switching Power Supply vs. Original Williams Power Supply
A lot of people want to put new switching power supply in their Williams game. You see conflicting reports everywhere about which is better. I am no expert on this matter but according to Bob Roberts either will work fine with a little work. If you rebuild your original it will be a good working supply. Order a rebuild kit here
If you decide to install a new switching power supply you need to install the lithium battery modification to replace the three aa battery holder on the board(this is a good idea anyway). A switching power supply is a good replacement solution for the old supplies.
Bob Roberts also sells a new switching power supply and quick connect kit for Williams games.(see link above) I personally like keeping the game original so I try to rebuild ones that are failing. Really what I am saying is that both can work for you its your choice. :)
Thats about it. I hoped this has helped anybody who needs it. That was the goal. If something is wrong or Im missing something then Im sorry and you can Email me at rw@ronwatts.com and i will revise it.