M7891-DC 2a fuse on +12? fixed!

From: John Lawson <jpl15_at_panix.com>
Date: Thu Feb 5 18:04:52 2004

On Thu, 5 Feb 2004, Vintage Computer Festival wrote:

> On Thu, 5 Feb 2004, CRC wrote:
>
> > To safely re-energize a piece of equipment that is long in the tooth
> > and has been sitting around for some time, you have to bring the
> > voltage up relatively slowly to allow the electrolytic caps to
> > re-polarize. Everyone who is collecting should own a good-sized Variac.
> > You power the box up by bringing the voltage from naught to the
> > operational level with the Variac over a period of about a second or

   Then duck! IMHO opinion, and over 40+ years experience, to reform
funky caps takes anywhere from a few minutes to over an hour, depending on
many variables. If you think you've formed an electrolytic in one second,
it was either tiny or good-to-begin-with.

  But the thing most folks forget is to somehow monitor the *current*
being drawn during the Process of Reformation.

 Here endeth the Lesson.



>
> One second? I've always been told to do this over the course of at least
> a couple hours in 5V increments.
>


 Again - it depends on the voltage/capacity of the filters involved, and
just how "bad" gthey are. One simply cannot place an arbitrary
voltage/time delta on all power supplies.

  The Ammeter (or it's analog) is here your friend.

Cheers

John
Received on Thu Feb 05 2004 - 18:04:52 GMT