Working on a Williams Laser Cue. The game boots up and goes into attract mode. When you push start everything works normally and then nothing like it's tilted. When this happens though it's like the sound of a record player slowing with the game sounds doing that. If you push start again everything is working until it repeats it again. Any ideas? Re-built driver board and re-pinned that large inter connect between the MPU and driver.
Do the lights and displays stay on?
If you have access to an eprom chip (2716 or 2816) and a chip programmer you could download and run these test ROMs: http://pincoder.reversion.ca
With them you can check individual parts of your entire machine. For random crashes I recommend testing the RAM and CMOS chips using these ROMs. they are more extensive than the Williams onboard tests.
EDIT: The current beta ROM set has somewhat limited support for system 7 compared to the ones I haven't officially released yet. If you'd like to try the latest and greatest send me a PM and I'll send you a link to download them.
With the coin door open:
Pressing the Diagnostic button on a properly functioning System 7 MPU will cause the 7 segment display to flash a zero and then go blank. System 7 diagnostics are a bit more useful than prior Williams game systems but are still not 100% trustworthy. If the MPU built-in-test software detects a problem with the game hardware, the 7 segment display will remain on with an error code displayed. Possible error codes are:
0 - and then goes out...all tests passed
1 - IC13 RAM or IC20 ROM failed
2 - IC16 RAM failure
3 - IC17 ROM failure
4 - IC17 ROM failure (duplicated test...yes)
5 - IC20 ROM failure or the coin door was closed or memory protect fault
6 - IC14 Game ROM failure
7 - IC26 Game ROM failure
8 - IC19 (5101) RAM failure or the coin door was closed or memory protect fault
9 - IC19 (5101 again) RAM failure or the coin door was closed or memory protect fault.
Tests 1,2,8,9 are not very reliable - lots of false positives - but if you do get a failure here you'll need to replace the related chip.
You can try it before and after the crash and see what you get. If the system truly is crashed you wont get any results at all AFTER the crash.
Note that running these built-in diagnostics the lamps and the displays will go out.
Let me know what you find 
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