Re: Asteroids Deluxe Problem

Do you get anything when you put the game into self test mode? If you look at that
troubleshooting document I would try some of the steps under "Paul's Tips" - particularly
B2. Personally, I've never had much luck with logic probes except when it comes to
measuring clock signals. I like to use an oscilloscope so that I can see what's going
on. If you're able to borrow a signature analyzer from someone - I like to use Peter
Fyfe's signature analysis help guide on gamearchive.com.

That's my bit of advice.

Matt

George Campbell wrote:

> I'm having trouble diagnosing a problem on an Asteroids Deluxe board.
> When the game is powered up, the Player 1 and 2 buttons flash too
> quickly and the monitor's spot killer is on. The game does not play
> blind. I have established the following:
>
> 1) Logic supply is a steady 5.25v. DAC supply from VR3 is 4.98(is this
> too low?)
> 2) All roms were checksummed and are good.
> 3) Tried working Ast Dlx board in the cab and it works fine.
> 4) Swapped out the 6502 from the dead board in the working board and it
> is good.
> 5) Replaced Y1 as it had broken off. Could not find a 12.096 mhz crystal
> locally so I substituted a 12.000mhz.
> 6) Removed and socketed L5. Isolated pin 1 and checked pin 40 of the
> 6502 - was stuck low. I found this test here:
> http://www.geocities.com/SiliconValley/Circuit/2940/asteroidtech/asteroidsrepair.html
>
> According to the above page, if pin 40 is low, the problem could lie
> within the MPU, the vector state machine or both. However, I found this
> test inconclusive as pin 40 on the good board was also stuck low and it
> works fine.
> 7) Checked E2 with a logic probe and compared results to the working
> board. Both were identical.
> 8) Probed the 6502 on both boards. The only difference was that pin 21
> on the good board was high and 21 on the problem board was pulsing.
>
> Note: Dip switch settings on the good board are identical to those on
> the dead board.
>
> Any suggestions on how to proceed?
>
> Thanks
> George
>
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Received on Sun Jul 8 13:12:52 2001