[OT] Dodgy electrolytic in 3COM hub

From: Witchy <witchy_at_binarydinosaurs.co.uk>
Date: Thu Mar 18 05:59:43 2004

> -----Original Message-----
> From: cctalk-bounces_at_classiccmp.org
> [mailto:cctalk-bounces_at_classiccmp.org] On Behalf Of jpero_at_sympatico.ca
> Sent: 15 March 2004 21:12
> To: cctalk_at_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
Received on Thu Mar 18 2004 - 05:59:43 GMT