Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!bryan
From: bryan@cs.utexas.edu (Bryan Bayerdorffer @ Wit's End)
Newsgroups: comp.sys.amiga
Subject: Re: B2000 power supplies
Message-ID: <338@mohawk.cs.utexas.edu>
Date: 3 May 89 18:21:32 GMT
References: <3285@hplabsz.HPL.HP.COM>
Reply-To: bryan@cs.utexas.edu
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In article <3285@hplabsz.HPL.HP.COM> dleigh@hplabs.UUCP (Darren Leigh) writes:
=-Well, my power supply just gave up the ghost.  It's especially

=-Here's a description of what happens: I turn it on, the fan starts up
=-and the +5 rail turns on nicely, then the fan shuts off and I only get
=-a volt or so out of the +5 supply.  I guess the power supply is
=-getting crowbarred?
=-
=-The power supply claims to be made in Hong Kong by Elec & Eltek Power
=-Supply LTD.  It is model number 420504-SD and has a date code of 8815.

	Yep, that's the very problem I had with the very same power supply
about six months ago, only mine was older (1/87).  The fan had started to sound
like its bearings were going to seize any minute, despite repeated meticulous
cleanings of the blades.  So, I tore it out of the cage and fiddled with
it---flipped and lubed the bearings, etc.  When I plugged it back in and
reassembled everything it ran ok---for about 15 seconds after reboot.  Uh oh,
power failure, thought I.  But no, the desk lamp is still on.  Hmm.  Try to
cycle the power.  It gets about 10 seconds into the reboot, and then, bereft of
life it rests in peace.  From then on all I get is the crowbar effect.
	It was natural for me to assume that I'd done something unspeakable
whilst messing with the fan and its immediate surroundings, but it turned out
that the big radial cap that sits next to the terminal into which the fan wires
are plugged (northwest corner of the board) had chosen that moment to spring a
leak bad enough to cause the supply to crowbar itself down.  Upon replacing
that capacitor, all was well.  I took the opportunity to swap the Hong Kong
Turbine for a Radio Shack 12VDC fan, which sounds significantly less like the
business end of a 727.

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