Broken Asteroids

PassivePac-Man

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All I get on the screen is a flashing image that looks sorta like the ship. The voltage at the board is reading 5.27 volts, which I assume to be okay. I replaced the big blue and capped the AR and reseated all socketed chips. Help?
 
It does not boot at all. I can't get a self-test. I thought it was the socketed chips, but I deoxited them today with no change. I just get a flashing image with a couple of lines. It is measuring 11.4 volts on the 10.3 volt test point on the AR.
 
Update: it's still not booting and I blew up a couple of the caps. Scared the crap out of myself lol. I'll be ordering a cap kit for the PCB tonight.
 
Which caps blew?

If it was C86/87, test the four diodes to the right of them. See if any are shorted.

Caps generally don't tend to just blow on these boards, unless they have been physically damaged (e.g., stepped on, etc), or if there is some other issue.
 
It was C86 and C87. I was testing voltages and accidentally connected the negative lead of 86 to the positive lead of 87. All diodes read .55. Thanks
 
It was C86 and C87. I was testing voltages and accidentally connected the negative lead of 86 to the positive lead of 87.


Well I guess that would fall into the 'some other issue' category, lol. ;-)


BTW, 11.4V on the 10.3V test point is normal. (It's usually anywhere between 11 and 14V, for different cabs.)
 
I fixed the output circuit stuff, and am still getting the same issue. Here's a picture of the image I get. It just flashes like that. Anyone know what's wrong?
 

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The board is 'watchdogging' (i.e., continually resetting, because the CPU is not happy). This can be due to many things, and without the proper tools, you likely won't be able to do much.

First thing would be to pull and verify the ROMs, in a reader. If you had access to another known good ROM set, you could swap them out, but it also could be a bad socket, so even that's not conclusive. But you want to make sure you're starting with good code as a first step, after verifying power (which you've already done).

Your best bet is to find someone to repair it.
 
Update: I swapped the roms with a known good set and tested the sockets by testing continuity between each leg on each socketed chip to the pad on the other side of the board. I'm still getting the same issue. I found this website: https://sites.google.com/site/asteroidsrepairlog/

On there, I found one detailing my problem and it says that the 74LS244 chip at B2 was the fix in that situation, so I think I'm gonna try that. Any input?
 
Update: I swapped the roms with a known good set and tested the sockets by testing continuity between each leg on each socketed chip to the pad on the other side of the board. I'm still getting the same issue. I found this website: https://sites.google.com/site/asteroidsrepairlog/

On there, I found one detailing my problem and it says that the 74LS244 chip at B2 was the fix in that situation, so I think I'm gonna try that. Any input?

Did you swap in a known good CPU also?

What kind of tools do you have on hand or access to?
 
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