H744 regulator whistle - test-drb@ccmp.vtda.org

13 Jan 2002

On Jan 13, 17:03, ajp166 wrote:
...
  From: Pete Turnbull &lt;pete(a)dunnington.u-net.com&gt;
 On Jan 12, 20:14, jpero(a)sympatico.ca wrote:

  Sounds like PSU is reacting to overloading or
medium shorts
 downstream of that PSU outputs.  Also can happen with dried
 up capacitors (too high ESR). 
I don't think it's any of those.  The regulators all make a similar  noise
 when I put them on a dummy load drawing 5A, on the
bench.  And I'm sure
it's not bad caps, as two of them are ones I repaired recently. 
 This is normal for them as well as the older H780.  They are very loud
 and the pitch varies with load as well.  That is a side effect of older
 low voltage, low frequency switch mode PS designs of some 20+ years ago. 
I suppose so, I just didn't think it ought to be so irritating!

-- 
Pete						Peter Turnbull
						Network Manager
						University of York