Sega G-80 boardset CPU Q6 blew apart???

Hello,

     I was running a switching power supply to a Sega G-80 boardset in a Star
Trek machine. Everything worked fine, then, the board wouldn't even boot. One
single flash on the CPU LED. After a careful inspection, Q6 (2n4401 in 555
curcuit) was blown apart. This is where the +2v AC would normally go, but I
had this tied to +5 because of the switching power supply to "appease" the
watchdog.
     I replaced both 2n4401's in this curcuit with 3904's, and everything is
fine now. Has anyone had a similar problem when running a G-80 set to a
switcher and putting the normally +2vAC to the +5 line?? I was wondering if
the 2n4401 just failed out of random chance, or if putting the +5 to this
curcuit could have caused this.

Thanks,
Michael Kelley
Received on Tue Jul 6 09:25:29 1999