I post this interesting response offered by my supervisor. Jim Knighten ________________________________________________________ Dr. Jim Knighten e-mail: jim.knigh...@sandiegoca.ncr.com <mailto:jim.knigh...@sandiego.ncr.com> Senior Consulting Engineer NCR 17095 Via del Campo San Diego, CA 92127 http://www.ncr.com <http://www.ncr.com> Tel: 858-485-2537 Fax: 858-485-3788
***** Notice my previous alert about a new external e-mail address was premature! ***** ***** Notice the Area Code change from 619 ***** -----Original Message----- From: Woolf, Bill Sent: Friday, July 09, 1999 1:56 PM To: Knighten, Jim L; Rostek, Paul M; Canizal, Julio C; Fan, Jun Cc: Smith, Norm W Subject: RE: EMC Detective and Flushing Toilet Jim, I suspect the problem is related to the unequal resistance in the plumbing of the house, creating "resistive gaps" and possible ground faults in the electrical wiring of the house. Many homes falsely rely on the plumbing lines to provide a good ground for the electrical systems. These things can happen, you know, with old houses and cheap home repairs. The ground faults appear to be causing emission problems which I'm sure you have seen before. After an exhaustive search of the WEB I came up with the follow article which I believe will fully explain the root cause: http://web.raex.com/~colombo/pipe.htm <http://web.raex.com/~colombo/pipe.htm> Bill -----Original Message----- From: Knighten, Jim L Sent: Friday, July 09, 1999 1:23 PM To: Rostek, Paul M; Canizal, Julio C; Fan, Jun Cc: Smith, Norm W; Woolf, Bill Subject: FW: EMC Detective and Flushing Toilet ________________________________________________________ Dr. Jim Knighten e-mail: jim.knigh...@sandiegoca.ncr.com <mailto:jim.knigh...@sandiegoca.ncr.com> Senior Consulting Engineer NCR 17095 Via del Campo San Diego, CA 92127 http://www.ncr.com <http://www.ncr.com> Tel: 858-485-2537 Fax: 858-485-3788 ***** Notice my previous alert about a new external e-mail address was premature! ***** ***** Notice the Area Code change from 619 ***** -----Original Message----- From: ed.pr...@cubic.com <mailto:ed.pr...@cubic.com> [SMTP:ed.pr...@cubic.com] <mailto:[SMTP:ed.pr...@cubic.com]> <mailto:[SMTP:ed.pr...@cubic.com] <mailto:[SMTP:ed.pr...@cubic.com]> > Sent: Friday, July 09, 1999 11:28 AM To: Bailin Ma; EMC-PSTC Subject: Re: EMC Detective and Flushing Toilet Barry: I would be tempted to say that the reboot is actually an undocumented feature in which bad data is automatically flushed from the system. But this actually sounds like a clear case of hydraulic hammer. In typical residential construction, all utilities, including water and electric power, are routed within the walls and under the subfloor. As the toilet flushes, the water closet fill valve rapidly opens. This creates a momentary drop in the supply line water pressure, causing the pipe to flex slightly. When the fill valve closes, the moving mass of water is suddenly forced to a halt, producing another flex in the pipe. The mechanical stress in the pipe is translated to the house structure, which in turn is flexing some electrical circuit. Over many years of repeated flushing, the buildup of repetitive strain has caused small faults to occur in the flexed power circuit. This causes momentary drop-outs in that circuit, which cause the computer to re-boot. Even if the circuit is a different one than the computer's power source, the electrical noise caused by the fault couples onto whole house wiring. The fault could even be located at the water heater, where a strap jumper is often used to electrically connect the inlet and outlet pipes to maintain ground continuity of the plumbing system. Fixing this is difficult, since it puts the customer's desires for computational efficiency in direct opposition to his personal hygiene training. Sure, the easy path would be to tell the customer that the toilet is simply not Windoze compatible, and that he must upgrade to Potty NT. But I think that there's an elegant way to fix this in software. The customer has obviously been making those nature calls during the operation of some particular program, let's say MS Word. The customer should simply put a shortcut, pointing to the path for winword.exe, into his Start Up folder. That way, when the computer re-boots, it will automatically re-start MS Word and re-load the work-in-process from the back-up copy. (To avoid significant work loss, the Auto Save option should be set to a short interval, like maybe 30 seconds.) Regards, Ed ------------------------ From: Bailin Ma <b...@namg.us.anritsu.com <mailto:b...@namg.us.anritsu.com <mailto:b...@namg.us.anritsu.com> >> Subject: EMC Detective and Flushing Toilet Date: Wed, 31 Dec 1969 23:00:00 GMT To: emc-p...@ieee.org <mailto:emc-p...@ieee.org> > > Greeting to the group, > > EMC engineers in a PC maker received a customer's complains transferred > from technical support group that every time he flushes toilet his PC > always reboots. Assuming you were one of EMC engineers, please participate > the discussion and try to answer following questions: > (1) Fabricate an EMC story to relate the cause (Flushing toilet) to the > effect (Rebooting PC). > (2) Direct the customer to verify your speculation. > (3) Fix the problem. > > Barry Ma > -------------------------- Ed Price ed.pr...@cubic.com <mailto:ed.pr...@cubic.com> Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 Date: 07/09/1999 Time: 10:28:06 Military & Avionics EMC Services Our Specialty Also Environmental / Metrology / Reliability -------------------------- --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org <mailto:majord...@ieee.org> with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com <mailto:ed.pr...@cubic.com> , jim_bac...@monarch.com <mailto:jim_bac...@monarch.com> , ri...@sdd.hp.com <mailto:ri...@sdd.hp.com> , or roger.volgst...@compaq.com <mailto:roger.volgst...@compaq.com> (the list administrators). --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
