Actually, these caps usually don't fail in equipment that's powered up
for long periods.
They fail after being unused for a long time and then returned to service.
----- Original Message -----
From: "Peter Brown" <peterbrown10_at_hotmail.com>
To: <cctalk_at_classiccmp.org>
Sent: Wednesday, November 17, 2004 1:35 PM
Subject: Re: HP 2113B service manual / schematics
> Hi Joe,
>
>>One of the things that I noticed was that the computer kept running and
>>even though I turned >off the power switch the cap kept sizzling.
>
> On the 2113 (and I guess from your description the 2117) the capacitor is
> directly across the terminals on the mains input socket - i.e. on the
> 'always hot' side of the on/off switch. So turning the power off behind
> the front panel of the computer won't help.
>
> In order to effectively control interference the capacitor has to be
> mounted as close to the point at which mains enters the equipment
> enclosure as possible. Mounting it further away causes the input leads to
> act like an antenna inside the enclosure.
>
>>I had to unplug the line cord to stop it.
>
> Yep, this is the only way to shut the power off to this capacitor, it is
> always live when the equipment is plugged into a live mains socket.
>
> A good reason NOT to leave this sort of equipment plugged in but turned
> off!
>
> Peter Brown
>
>
Received on Wed Nov 17 2004 - 18:56:51 GMT