Re: Audio Reg II board smoking?

On 1/8/98, at 4:19 PM, Duncan Brown wrote:

>Steve,
>
>> However, when I swapped back in the Asteroids board, R30, on the Audio
>> Reg II started smoking! (Retesting with the Asteroids Deluxe board and
>> the smoked Audio Reg II showed that there was no damage.)
>> Unfortunately, I didn't have any schematics to Asteroids Deluxe or
>> Tempest available at the time. Any guesses why I'd see this behavior?
>
> I don't have my schematics memorized yet, but I'm going to take
> a stab at this as being the infamous "sense resistor problem."
>
> Atari overdesigned their supplies and included a feedback loop on
> +5V (+sense) and ground (-sense), to account for any voltage drop
> in the wiring harness. Niice idea, but if you look at the circuit
> and then imagine the normal 5V and ground connections being
> interrupted for some reason (like, say, the ever-fail Atari board
> edge connectors), you'll notice that the power and ground can
> still get to the logic board, and very much want to...but they
> have to pass through a 1/4W resistor to do it...and they do, with
> the predictable result.
>
> Once you reseat the board and get the supply connections going
> good again, everything works fine, but now you have an open in the
> sense circuit because the resistor is fried.
>
> Fix your edge connectors, replace the resistors, and you're good
> for another couple of dozen board remove/insert operations.
>

Ah, this would explain why I have a pole position cockpit with two
AudioII/Reg boards with friend resistors, yet the game continues to work
fine.

-Warr

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Reviewer, "Windows Magazine" | Warren Ernst - warren@techie.com
Author, "Using Netscape" | http://www.cris.com/~wernst/
"Internet 1997 Unleashed" (c) | Computer Journalist, Consultant, Author
"Netscape 3 Unleashed"(contr) | Graphic Artist, Nerd
"Presenting ActiveX" |
Que and Sams.Net Publishing | "If it ain't broke, don't break it."
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Received on Thu Jan 8 14:49:06 1998