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From: blgardne@esunix.UUCP (Blaine Gardner)
Newsgroups: comp.sys.amiga
Subject: Re: ASDG Fast ram chirps?!
Message-ID: <459@esunix.UUCP>
Date: Tue, 25-Aug-87 10:17:42 EDT
Article-I.D.: esunix.459
Posted: Tue Aug 25 10:17:42 1987
Date-Received: Sat, 29-Aug-87 03:47:31 EDT
References: <8708211723.AA10752@THYME.LCS.MIT.EDU>
Organization: Evans & Sutherland Computer Corporation
Lines: 30

in article <8708211723.AA10752@THYME.LCS.MIT.EDU>, atheybey@bloom-beacon.MIT.EDU says:
> 
> I just bought an ASDG 8M/2 board (8Mb board w/ 2 Mb installed), and a
> Mini-Rack C.  Sometimes, the board chirps (for lack of a better word)

Mine also does this, but you're a little bit off the track, it's the
power supply, not the RAM that is chirping. (I've got a fully stocked 2
Meg board in my Minirack C, for the record.) The chirping really bugged
me when I first got the expansion, and I talked to Perry about it. He
told me that it would diminish as the power supply burned in, and it
has. The chirp is barely audible now, or maybe I'm going deaf. :-)

Chirping from switching power supplies isn't new to me, some of the
machines at work really "sing" when there is some heavy-duty video
updating going on. (I guess this means that the Amiga is just like the
big boys now! :-)

When the chirp was loud enough to irratate me, I took the time to isolate
the source of the noise, and it was the large transformer on the power
supply. During heavy accessing of Fast RAM, the transformer would
resonate, and cause the chirping sound. You needn't worry about your
RAM, my ASDG expansion has worked flawlessly for about 6 months now.

P.S. Using the TimeRAM program that was posted a while back, the 2 Meg
     ASDG board clocks 18% faster than Chip RAM. 
-- 
Blaine Gardner @ Evans & Sutherland    540 Arapeen Drive, SLC, Utah 84108
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