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
