Asteroids/G05-805 Struggles

AllenBomber

New member
Joined
Dec 17, 2009
Messages
372
Reaction score
0
Location
Boulder, Colorado
I figured I'd post my story either for input or just for a fix (hopefully) record.

I picked up an asteroids cocktail machine non-working but it had neck glow. I had solid lights on the P1/P2 start buttons, but she wouldn't play blind.

I happened to have an Asteroids Deluxe cocktail too, so I dropped my known good Asteroids deluxe board into it and she played perfect. I figured it was the main board, so I'd just located another. I picked up a new board from eXidy. He said this board was repaired by Mike Salay and it was running as of a few months ago. It had a few graphical glitches, but it was probably a rom error. No problem, as I figured I could make one good board out of the two. My non-playing error turned out to be a rom error in the 035145 (E/F2) Rom (Top corner, closest to the main processor) and I had a running machine. I had it running for like 30 seconds, then flashes of light and magical smoke emerged from my GO5 deflection board. R605, 608 and 613 were all toast in addition to popping F101 and F600. I replaced the resistors but went searching for a cause and found Q606 to be shorted across two leads. Q606 is an MPSU57 transistor, and my local shop didn't have them. A week later, I had a new one from Bob Roberts and I set to work. All installed, and she blew up within 3 seconds in nearly the same way except this time, R605, 613 and 618 went. No fuses this time as I had 2 and 5A breakers in place of F101 and F600 respectively, but nether tripped. I pulled my new MPSU57 only to find that it was shorted just like the last one. (there went 12 bucks!) I went brute force attack style. Tested every diode (all looked fine) and pulled and tested every single transistor on the board finding Q605 to be shorted across all 3 leads.

We'll see in a week when my new MPSU57 and 2N3906 (Q605) shows up, but right now I'm a little frustrated.

I'm still not sure if I have reached the root problem, and I still don't know if it was my new main pcb causing the problem, or it was just time for something to blow up. Either way, I'm scared as hell to test this new PCB in my known working machine for fear of blowing up that vector too.
 
Minor update... When ordering more parts, Bob Roberts suggested I check the pins at P600 to make sure there weren't any shorts there. The pins tested fine, but it got me thinking about what plugs into P600. Found both of the case mounted transistors, (2N3716 and 2N3792) have faults as well. The 700 set of identical transistors was fine, but my entire 600 circuit seems to have gone up in smoke. Any idea what would cause a previously working monitor to just die so catastrophically?
 
Sometimes they just do that....my Omega race did just that the other day. I would check the board with a scope hooked up to it and unplug your monitor power. That should give you an idea of the sort of voltages coming out of it. You need a scope with X Y mode to see a picture though.
 
Back
Top Bottom