HP 2113B service manual / schematics

From: Peter Brown <peterbrown10_at_hotmail.com>
Date: Wed Nov 17 12:35:09 2004

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 - 12:35:09 GMT