David Oh dear, I was going to post a similar help message. Same problem except it is an audio amplifier and the test is radiated immunity.
I can't possibly fathom out the demodulation process so I have to stop the RF getting in to the product. It doesn't help having the input and output grounds isolated from the chassis (for so called sonic reasons). I have made a significant improvement by a liberal sprinkling of 100n caps from signal ground points to chassis and secure EMC bonding of the chassis components. Hopefully a few more 100ns should clear the problem completely. >From this experience I guess you too might have a grounding problem. Try the magic wet finger and a few caps. Regards Chris Colgan Compliance Engineer TAG McLaren Audio Ltd The Summit, Latham Road Huntingdon, Cambs, PE29 6ZU *Tel: +44 (0)1480 415 627 *Fax: +44 (0)1480 52159 * Mailto:[email protected] * http://www.tagmclarenaudio.com > -----Original Message----- > From: David Gelfand [SMTP:[email protected]] > Sent: 24 May 2001 19:28 > To: [email protected] > Subject: EN 55024 Annex A.1 > > Help! > > When we inject as per IEC 61000-4-6, the 1 kHz tone is demodulated and > is VERY loud in the telephone earpiece! This happens no matter which > i/o cable we inject, even the power cord. The conducted RF appears to > re-radiate inside the chassis and is being picked up by the line card. We > use an AMD/Legerity Am79R70 chip, it is very sensitive at the RSN pin. > Has anyone experienced similar problems? Has anyone passed this test with > this chip, or with another? > > Thanks in advance, > > David. > > David Gelfand > Regulatory Approvals > Memotec Communications Inc. ************************************************************** Please visit us at www.tagmclarenaudio.com ************************************************************** The contents of this E-mail are confidential and for the exclusive use of the intended recipient. If you receive this E-mail in error, please delete it from your system immediately and notify us either by E-mail, telephone or fax. You should not copy, forward or otherwise disclose the content of the E-mail. TAG McLaren Audio Ltd The Summit, 11 Latham Road Huntingdon, Cambs, PE29 6ZU Telephone : 01480 415600 (+44 1480 415600) Facsimile : 01480 52159 (+44 1480 52159) ************************************************************** Please visit us at www.tagmclarenaudio.com ************************************************************** ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
