17 Mar
2004
17 Mar
'04
9:59 p.m.
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org] On Behalf Of jpero(a)sympatico.ca
Sent: 15 March 2004 21:12
To: cctalk(a)classiccmp.org
Subject: RE: [OT] Dodgy electrolytic in 3COM hub
Beauiful photo of this swelled up electrolytic capacitor. :-)
What is that digital photo camera?
It's a Fuji 6800Zoom plus tripod 'cos without one I've never been able to
get a really clear shake-free picture; witness most of the pix on Binary
Dinosaurs :)
The 7 legged "transistor" is a efficient
regulator IC switcher that
down converts input voltage to specific voltage. Good to about 1
amp or so with little heatsinking.
This is a 3 year old 3com hub so I'd assume efficient technology in
there....
That whistle is the noise of that regulator switcher
it works
at high freq. They runs too high freqs to hear but when they
get loaded down or bad caps, they decrease in PWM (more ON
time) trying to keep voltage up (more power transfer, then u
can hear the noise. The swelled up cap is already GONE btw.
Ah right! Ta for that - I was wondering how a bust cap could make noise!
Cheers
w