Re: Defender power supply requirements

> I have used both computer and video game switching supplies with no
> problems on my Williams games. No issues with corrupt memory - and 'if'
> that is the case I would suspect that the power-up reset circuit on the MPU
> is failing. After all CPU's all want about 2 - 500ms of RESET before going
> 'live' and any switching supply worth it's salt will provide power in under
> 100ms. So if you have a problem with memory corruption, then I would be
> replacing any timing capacitors in the RESET circuit...

Yeah, that has been my experience with all of the ATX switchers I've
witnessed on a scope.

> As far as I can see Williams made no effort for their supply to come up in
> any particular order...they all boot at once.

Well, there is this nasty resistor/transistor circuit that looks to
qualify both the 5 volt rail and the 12 volt rail (at least) and it's
connected to the system wide reset. So maybe the supply doesn't come up in
any particular order, but the logic circuit definitely qualifies them
both.

So what do I connect the "12 volt unregulated" to on Defender? Just the
+12 volt rail? All it appears to do is go to the big, nasty, evil
resistor/transistor/zener circuit that controls reset.

And I, of course, have purchased several ATX power supplies dirt cheap.
Any recommendations on a specific wattage? I can't imagine it pulling more
than a desktop PC.

-->Neil

-------------------------------------------------------------------------------
Neil Bradley In the land of the blind, the one eyed man is not
Synthcom Systems, Inc. king - he's a prisoner.
ICQ #29402898

---------------------------------------------------------------------------
** To UNSUBSCRIBE from rasterlist, send a message with "UNSUBSCRIBE" in the
** message body to rasterlist-request@synthcom.com. Please direct other
** questions, comments, or problems to neil@synthcom.com.
Received on Thu Feb 20 08:55:28 2003