Hello everyone: Another method is to apply power for only 2-3 seconds; Much safer for switching supplies than low voltage. This charges up the capacitors; If capacitors are leaking, there is no source of current to cause overheating or other failure modes. The charge which remains on caps allows electrolytic barrier to "re-form". Repeat this a dozen times over the course of a day.
Tom Buehl At 03:23 AM 4/4/2006, Robert Atkinson wrote: >Hi all, > >Using a Variac over a long period of time is great with conventional >(Transformer-rectifier-capacitor) linear PSU's, but be careful with more >modern equipment with switchmode PSU's. They can draw excessive current >during undervoltage conditions. >Still use your Variac, but ramp it up a little quicker, maybe 30s to a >minute. Watch out for auto supply voltage (115/230) switch designs too, >it's best not to cross the switching boundary too slowly as they may not >switch back from voltage doubling to full-wave rectification resulting >in very excessive internal voltages. >If you don't have a Variac, try a low wattage (40W) light bulb in series >with the supply to limit the current. > >Robert G8RPI. > >-----Original Message----- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On >Behalf Of Poul-Henning Kamp >Sent: 04 April 2006 06:28 >To: Discussion of precise time and frequency measurement >Subject: Re: [time-nuts] Fw: HP 105 powersupply problems > >In message <[EMAIL PROTECTED]>, >"Richard and M >arcia Putz" writes: > > >I had similar problems with my HP105, not bad transistors, check > >out the filter capacitors. Electrolytics in any equipment past 15-20 > >years of age could be suspect. I'd look there first. > >In general when powering up equipment that has been turned of for >years: Use a variac and ram the voltage up slowly over a couple of >days. > >Electrolytics can loose their polarisation over time and if exposed >to full voltage they are likely to splatter all over the place, but >if you give them a slow start they will most often recover their >polarisation and work fine. > >-- >Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >[EMAIL PROTECTED] | TCP/IP since RFC 956 >FreeBSD committer | BSD since 4.3-tahoe >Never attribute to malice what can adequately be explained by >incompetence. > >_______________________________________________ >time-nuts mailing list >[email protected] >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >Any opinions expressed in this email are those of the individual and not >necessarily Genetix Ltd (Genetix) or any company associated with it. This >email and any files transmitted with it are confidential and solely for >the use of the intended recipient. If you are not the intended recipient >or the person responsible for delivering to the intended recipient, be >advised that you have received this email in error and that any use is >strictly prohibited. If you have received this email in error please >notify Genetix by telephone on +44 (0)1425 624600. > > >The unauthorised use, disclosure, copying or alteration of this message is >strictly forbidden. This mail and any attachments have been scanned for >viruses prior to leaving the Genetix network. Genetix will not be liable >for direct, special, indirect or consequential damages as a result of any >virus being passed on, or arising from alteration of the contents of this >message by a third party. > >_______________________________________________ >time-nuts mailing list >[email protected] >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
