Re: GS Power Supply: Warning signal?

[Rubywand <rubywand@swbell.net>]

Itsme writes ...

>> .

Hmmm..

I noticed my GS is making some new noises (coming from the power supply)

This started about a week ago.  I have a Transwarp installed, and a few
other cards.

I need to get a heavier supply from Steve and a good fan.

I wonder what is making the buzz that I hear in the PS?
<<


     There are two or three places a buzz may come from. If your PS has a 
relay-type thing in the voltage-sensing/control circuit, that is a pretty 
good suspect. This is the part that clicks when a PS output is shorted. 
(Sometimes, the transformer makes sounds; but, usually, these sounds are 
pretty high-pitched.)

     The buzzing does not necessarily mean that your PS is bad. It may be 
an indication that something needs to be changed.


     The hardest part about convincing owners of modern, 
accelerated/memory-boosted/RamFAST-equipped/... GS's of the need for 
beefing-up leads on the PS is easy to pinpoint: Everyone finds it 
difficult to believe that Apple Computer would be guilty of such a silly 
design screw-up. Yet; there is no way the original leads can support the 
+5V line at anything like the current output at which the GS power supply 
is rated. (Depending upon the cards plugged in, the +12V lead could 
present a similar problem.)

     In a reasonably loaded GS, the skimpy +5V and GND leads become 
resistors across which significant noise voltages develop. Aside from 
producing system glitches, my guess is that the noise supplies false 
information to the PS load/voltage sensing circuitry which leads to 
failure. (The failure mode may be similar to that described for 
under-loaded PC power supplies.)

     The idea behind fattening at least the +5V lead and one GND lead 
(to, say, #10 or #12 gauge) is that the lead resistance will be so low 
that, even at 3-4 Amps, no significant voltage will develop on the leads. 
Your GS will be happier because the noise that used to appear across the 
leads, propagate through the system, and cause bombs is gone. You PS will 
be happier because it knows how much current to deliver.
  

Rubywand