Tempest: game only boots AFTER test mode

scoots

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a friend and i have been battling this tempest forever it seems. we are getting close, but it is still not right. starting out we had vertical collapse/played blind. we replaced the 1495 chips at A/B12 and A/B13 and two roms (111 and 117 iirc) and that got us a basically correct picture in test mode (baby steps). all the other roms tested ok.

the main problem now is that the game will simply not just start at power up. it will only start if you first put it in test mode and THEN switch over to game mode. on a couple of occasions it also spontaneously reset, though on our last power up it seemed to be functioning well once it started.

we tried swapping CPUs from a known working board but it did not solve it. this work is being done on my friend's test bench so we're certain it is the board (other tempest/black widow boards worked perfectly on it). i don't think the aux board/cable is a problem since it worked perfectly with his known working board.

any thoughts?
 
Reflow the pins on both inter-board connectors. Test mode will run with the smaller board completely disconnected but the game won't.
 
I am no expert but that sounds like a power issue. Watch the +5 volts and see what happens. I had a Stargate that would do something similar. Ended up rebuilding the power supply. It was right on the verge of +4.8 and while it was booting it would drop below that.
 
I am no expert but that sounds like a power issue. Watch the +5 volts and see what happens. I had a Stargate that would do something similar. Ended up rebuilding the power supply. It was right on the verge of +4.8 and while it was booting it would drop below that.

Big Blue ?
 
big blue has already been replaced.

we did verify all voltages on my ARII. same problem when hooked up to a friend's. in contrast, his game board worked perfectly in my cabinet.
 
it might be the cable.
the one that connects the 2 boards
try disconnecting the cable completely and put the board in the game and hook it up.
If you get the same problem then you know that the cable is bad.
I am just basing this off of what the poster said in this tread about you can run test mode without the small board.
but you may have a bigger problem going on too.
good luck
 
it might be the cable.
the one that connects the 2 boards
try disconnecting the cable completely and put the board in the game and hook it up.
If you get the same problem then you know that the cable is bad.
I am just basing this off of what the poster said in this tread about you can run test mode without the small board.
but you may have a bigger problem going on too.
good luck

well, i did try my cable and aux board on friend's known working board, and it was fine.

i don't have an ESR meter but i do have all the caps to do the pcb so i guess i can try that next.
 
It would help to know if the CPU is being reset by the watchdog, or if it's the vector state machine. When the game fails to boot, check pin 40 of the CPU with a logic probe.

Then, press the reset button on the main board a few times to see if that will get it going.
 
The only thing I've seen that was similar was caused by the crystal going bad. i would at least check the components in the clock circuit for cold solder or bad parts. also make sure you are measuring voltages on the game and not just the ar board. Id have to check but a good majority of the electrolytic caps are for sound. I've only had to replace missing or damaged ones before.

also check your clocks on the aux and game board when booting directly to game mode.
 
recapped the main pcb and aux board and replaced the crystal and it is booting up properly now.

occassional random resets but i'm 99% sure it is due to my hacked up edge connector. is there a better way to repair a pcb edge connector than that kit bob roberts sells?
 
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