Date   : Mon, 31 Oct 2005 00:56:26 -0000
From   : "David Hunt" <dm.hunt@...>
Subject: Re: Guess age from serial number?

> Quoting Annihilannic <annihilannic@...>:
> 
> > Anyway, last night I was happily typing in the Lunar Lander programme
> > from the BBC User Guide with the beeb sitting on my lap when suddenly
> > pfffffft! and some foul smelling white smoke started floating out of
> > the
> > speaker holes... I switched it off and turned it over, and more white
> > smoke came out of the vents underneat... I guess my leg was covering
> > the
> > vent under the power supply. It had been on for an hour or so... could
> > that be the only reason, or is the PSU just showing its age? The
> > machine kept running, and still boo-beeps when I plug it in, although
> > I'm hesitant to leave it on now.
> 
> This will be the mains supressors in the PSU giving up. They are labelled
> C1
> and C2 and it would pay to replace them both. Quite easy and cheap to do
> too.
> 
> 250V AC Mains - Metallised Polypropylene Capacitors - X2 0.01uF
> 250V AC Mains - Metallised Polypropylene Capacitors - X2 0.1uF
> 
> It's a common problem and the machine will run without them but you might
> get
> interference on other devices.
> 
> Cheers,
> 
> Mike.
> 
> --
> Michael Foot <mjfoot(at)paradise(dot)net(dot)nz> *
> http://homepages.paradise.net.nz/mjfoot/
> * Replace letters between () with @ and . when replying

Yes, I had the same problem a while back, had a Beeb upstairs and a laptop
downstairs copying stuff over a serial cable connected to a PC I was using
Remote Desktop to.

The trouble was it was the hottest day in Cambridge on record. 

I just happened to go upstairs and the room had a lot of smoke in it. The
Beeb was still working, it took a while to find the culprit, I found out
when another capacitor blew in the same fashion. A kind of whooshing noise,
then a loud pop and the Beeb was surrounded in a dense white fog, but it
kept on working. The temperature of the Beeb PSU (measured with my handy
Fluke) was 92 degrees Celsius! 

Like Mike says, easy to replace those caps, but it is probably unwise to use
the Beeb for any length of time until they are replaced.

Dave ;)