PAL problems

[Christopher Bock]

I received my PAL last month but I haven't really gotten a chance to play with it or build any of the other boards yet. It fired up just after I finished it. I entered in a counting program and it worked great. I turned it off. I fired it up the next day to play some more. It came on fine, but my wife called me to do something so I left running it for 15 minutes or so before I came back. When I came back the displays were off and I couldn't get  them to come back on. I tried switching power supplies to a different 7.5v dc adapter. Nope. Tried reseating the ICs. Nope. Checked for any cold solder joints. Didn't see any. I could see a 1mhz clock signal on pin 37 of the CPU. I then tried bypassing the voltage regulator and tied regulated 5v from my bench supply into the Vcc line thinking maybe I was having a current supply issue and that maybe my power adapters were bad. Nope. But I think I might have accidentally caused a short with the bench supply, because when I checked the clock again the clock signal was gone. I then waiting a few weeks for a supply of new 1mhz oscillators to arrive. They arrived today, so I popped in a new one. And guess what. It worked perfectly again. I began thinking that maybe the oscillator was bad the whole time. 

This is when, and I kid you not, my wife called me to help with something again. So I left the machine running for 10 minutes or so. I came back and the display was out. I can't get it to come back. I did check the clock with my oscillscope and I am getting a 1mhz square wave at the 6502.

Any ideas before I print out the schematics and begin probing around?

Chris