Upon the date 12:39 PM 4/23/99 -0700, ss_at_allegro.com said something like:
>Re:
>
>> > Is this a good idea? [slow power up]
>>
>> I'm on the fence about it. On the one hand you will find out if you've got
>...
>> YES. Especially under load. The thing that often fails in a PSU is the
>> filter capacitors and weak ones will show up as ripple and ripple will
>
>Several friends who collect old radios swear by the VARIAC. They
>claim that the old capacitors "dry out", and that running them at,
>say, 80 V for a few hours (or a day) rejuvenates them. I've heard
>time requirements vary from an hour to a day, unfortunately.
Variac is a trademark name for a variable transformer made by the old
General Radio Company in MA which came into common usage like the Crescent
brand of adjustable wrenches has. Anyway, being an old radio nut, there is
much truth in what ss wrote as I've been restoring AC operated radios for
just under 30 years.
I can send privately some comments I kept from one of my radio email lists
in reference to reforming electrolytics and what happens to cause them to
fail. Not appropriate on-list as it would actually be off topic. I just
have to hunt them up from either the list's archives or mine first.
Those comments discuss the technical aspects of how an electrolytic
capacitor will literally degrade over time and need to be reformed well
during its next power-up. Reforming steps are also discussed. A shorted
electrolytic as a result of the dielectric either deteriorating from disuse
or even occasionally from just slamming its normal working voltage on it
after years of being idle is not too much fun. Rather rare to happen, but
trust me, not fun. The computer-grade electrolytics we usually see in our
computer gear may not be immune to such failures but I haven't yet seen one
yet.
Incidentally, as for Crescent wrenches, the original Crescent Tool Company
which began here in Jamestown made them. Invented by a Swedish immigrant in
1905 down on Harrison Street just off Brooklyn Square. Crescent was bought
by Cooper Group in early 70's and everything hauled down to North Carolina
where labor and other costs (especially taxes!) were cheap. Xcelite tools
(nutdrivers, screwdrivers, etc.), from nearby Orchard Park (Buffalo
suburb), met the same fate a bit earlier. At least Chan-nel-lock
(adjustable gripping pliers) from neaby Meadville, PA is still in its home
town. Everything headed South from the industrial Northeast during the 70's
and 80's it seemed.
That's my bit of off-topic info for the day :)
Regards, Chris
-- --
Christian Fandt, Electronic/Electrical Historian
Jamestown, NY USA cfandt_at_netsync.net
Member of Antique Wireless Association
URL:
http://www.ggw.org/awa
Received on Fri Apr 23 1999 - 22:17:21 BST