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Article #2252Re: Source of ripple in simple PS circuit?
From: Michael A. Terrell
Date: Tue, 20 May 2003 10:01
Date: Tue, 20 May 2003 10:01
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2749 bytes
DaveC wrote: > > Replaced the rectifier bridge. Hum is gone (well, 90 percent of it). What > remains is a quiet buzz that you can hear only if you put your ear to the > speaker. I think all commercial-grade stereos have some buzz in the output. > > I suspect that the bridge was under-designed. The current throught the +15 > volt circuit is about 1A. The bridge is rated at that. The fuses (between the > transformer and the bridge) were designed to be 2A (as silk screened on the > PCB); 3A fuses were found installed. Makes you wonder... > > Unit is an H-K model AVR 65. > > Some ripple (a few tenths of a volt p-p) remains, but the v. reg is > responding well and is able to suppress it. > > Thanks to all who contributed suggestions, > -- > Dave C > dave+usenet3016@mailblocks.net You probably had an open diode in the old bridge rectifier Some of the early ones would run hot and the internal connections would open or become intermittent, as they got older. -- Michael A. Terrell Central Florida
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 112d1e,80288951613ef33a X-Google-Attributes: gid112d1e,public X-Google-Thread: 103407,80288951613ef33a X-Google-Attributes: gid103407,public X-Google-Thread: 10d137,80288951613ef33a X-Google-Attributes: gid10d137,public X-Google-Thread: 1131b0,80288951613ef33a X-Google-Attributes: gid1131b0,public X-Google-ArrivalTime: 2003-05-20 03:03:28 PST Path: arc1-ca.pugleaf.net!archiver1.google.com!news1.google.com!newsfeed.stanford.edu!cyclone.bc.net!sjc70.webusenet.com!news.webusenet.com!newsfeed2.earthlink.net!newsfeed.earthlink.net!stamper.news.pas.earthlink.net!newsread1.prod.itd.earthlink.net.POSTED!not-for-mail Message-ID: <3EC9FD41.7CF5E71B@earthlink.net> From: "Michael A. Terrell" <mike.terrell@earthlink.net> Organization: Resistors to the left, Capacitors to the right, and no talking! X-Mailer: Mozilla 4.78 [en]C-CCK-MCD (Win98; U) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: sci.electronics.design,alt.engineering.electrical,aus.electronics,sci.electronics.repair Subject: Re: Source of ripple in simple PS circuit? References: <0001HW.BAEDC6B30001868DF0386600@news.cis.dfn.de> <3R3ya.2176$OB5.464467@news4.srv.hcvlny.cv.net> <0001HW.BAEE339B0002EF2BF0386600@news.cis.dfn.de> <Ybhya.288$e_3.7@news02.roc.ny.frontiernet.net> <0001HW.BAEF0876000FF444F0386600@news.cis.dfn.de> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 29 Date: Tue, 20 May 2003 10:01:20 GMT NNTP-Posting-Host: 165.247.72.137 X-Complaints-To: abuse@earthlink.net X-Trace: newsread1.prod.itd.earthlink.net 1053424880 165.247.72.137 (Tue, 20 May 2003 03:01:20 PDT) NNTP-Posting-Date: Tue, 20 May 2003 03:01:20 PDT