Date: Fri, 25 Jun 1999 22:34:28 +0800 From: Peter Wemm <peter@netplex.com.au> To: freebsd-alpha@freebsd.org Cc: msmith@freebsd.org Subject: AARGH!! "dead" Alpha 164SX (Was: Re: OK, any pointers on how to use SRM? :-)) Message-ID: <19990625143428.6214475@overcee.netplex.com.au> In-Reply-To: Your message of "Sun, 20 Jun 1999 17:22:22 %2B0800." <19990620092222.426DB75@overcee.netplex.com.au>
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Peter Wemm wrote: > Christian Weisgerber wrote: > > Peter Wemm <peter@netplex.com.au> wrote: [..] > However, I have another problem that I could do with some advice on. > Basically at the moment I'm short of an ATX power supply and case (damn > weekends). So, itching to get going, I took my workstation apart and > mounted the AlphaPC 164SX motherboard. However, the power supply promptly > expired. (!) > > Apon investigation, with the old motherboard back in, the +3.3V power lines > from the power supply was supplying 1.9V instead and the hardware monitoring > was having a fit and making ambulance siren sounds from the speaker. (!!). > > After checking the 164SX motherboard again, I find the +3V-to-gnd > resistance is very close to 0.0 ohms, sometimes it sits at 0.2 ohms for a > few seconds after first attaching the DMM leads. > > Taking out the CPU brings the +3.3V-to-gnd resistance to over 1K ohms, which > is in line with the other supply pins on the motherboard. Well, the problem has been found.. Mike Smith gave me a new graphoil pad to use since the heatsink was taken off for transit.. But the new one was bigger than required and the thought never occurred that it might have been rather conductive and that it was going to short out those 12 capacitors on the top of the CPU surface, which, BTW, were between 3.3V and ground. So, the thing had pulled more than 14 amps of 3.3V through the graphoil/ heatsink and killed the first ATX power supply.... The second one I got had some sort of current limiter and was happily pumping 14+ amps through the motherboard to the cpu and loosing regulation (dropping to 1.2V). It all makes sense now. "Aargh Shit!" certainly seems appropriate. Anyway, after some careful trimming of the pad, I've now got it running to the point of SRM startup... (And there was I thinking I'd found a hairline crack in one of the mounts for a component from transit damage in my luggage..) Cheers, -Peter To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message
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