View Comments: Oldest First|Newest First|Threaded View
Page 1/2  >  >>
Beth Stackpole
User Rank
Back to the basics
Beth Stackpole   2/17/2012 7:12:41 AM
Now that is a Sherlock Ohms tale I can relate to. How many times does the root cause of the problem end up being something so basic, but likely often overlooked because you're searching for the complicated problem.

User Rank
Wiring Problems
naperlou   2/17/2012 9:55:55 AM

Ah, the old crossed wiring problem.  While you might think this would be easy to catch, it obviously isn't.  It is good that they were able to diagnose and fix the problem without any long term consequences. 


When I was working on satellites we were warned about the reversed sign problem in attitude control systems.  Surprisingly one got by the extensive testing and the satellite was sent into deep space instead of into near earth orbit (oops!).


Rob Spiegel
User Rank
Re: Wiring Problems
Rob Spiegel   2/17/2012 3:12:53 PM
Wow, Naperlou, how often does that happen? I would imagine the satellite mistake was a multi-million dollar goof. Can a mistake like that be corrected? Could the satellite be brought into near orbit?

User Rank
Case of the Reversed Power Switches
Walter   2/21/2012 1:15:01 PM
This incident sounds a lot like the one I had contributed where one of three pumps was running without power.  There was a bad check valve and the other two were driving it backwards.  In the case of the Reversed Power Switches also, the one blower was driving the other backwards.  Just because a motor is spinning does not mean there is power on it.

User Rank
Re: Back to the basics
KGround   2/21/2012 4:48:59 PM
Maybe this would be worth a case by itself, but since it is similar in nature, I add it here.

Today I discovered the hard way that you can reverse a split capacitor motor by forcing it to turn bbackwards while the motor is running.  If the connected equipment can overpower and stall the motor and cause it to turn backwards it will happily reverse direction and continue running in reverse until the next time the power is turned off and back on.  I had seen this before (not knowing exactly what i was seeing) on larger motors of several Hp with failing capacitors driving pumps against back pressure, but this present incident is with nearly a new fractional Hp motor.  Thanks to the folks at Brother tech support for educating me on this. 

George Merriman
User Rank
Similar problem
George Merriman   2/21/2012 5:29:28 PM
Some time back I checked into a motel while on a road trip. The weather was mild, but the room became very warm after a few hours. I went to the air conditioning control and turned on the cooling. The room became warmer. The more I turned down the temperature the warmer the room became.

I called the desk and asked for another room. When the night manager came to help me move rooms he explained that they had been having similar problems since the air conditioning system was upgraded a few weeks earlier. The wiring for some of the room controls had interchanged so that my control was setting the temperature for another room and visa versa. Someone checked into the other room after I arrived and felt that the room was cool, so turned on the heat in my room. I started getting warm, so I turned on the cooling in the other room. One thing led toanother, and I was roasting while the other person was freezing!

Jon Titus
User Rank
Re: Similar problem
Jon Titus   2/21/2012 6:01:29 PM
In 1985, when Cahners Publishing Company, then the owner of Design News, moved into a new building the staff had a difficult time regulating the temperature. The HVAC people had mixed up the thermostats so the editorial groups regulated the temperature on the executive side of the building and vice versa.  The execs got cooler and thus turned up the heat on the editors (literally), who then adjusted their thermostat to further cool the execs. The initial solution was to place locked plastic enclosures around the thermostats, but the editors--many of whom were engineers--quickly subverted the "lock out" and the cycle repeated itself until someone got the HVAC guys in to check out the system. They uncrossed the controls.

Bill Carton
User Rank
Re: Similar problem
Bill Carton   2/21/2012 7:39:54 PM
The crossed thermostat problem bit my wife and me one cold night in New England, but with a much faster time constant.

We had accidentally flipped over our dual-control electric blanket while remaking the bed.

Her control and mine were each slammed to opposite stops within 3 minutes.

Hilarity ensued as I did the troubleshooting. That was 30 years ago, and it still gets laughs at cocktail parties.

User Rank
First Job
Tool_maker   2/22/2012 6:50:39 AM
I love stories of first real work experiences. We all start our jobs with book learning and abstract theories only to run slam into the real world. My first concerned a bandsaw with a spring loaded tensioner. Every time I broke a blade, the spring unloaded with a loud bang and was quickly followed by catcalls and ridicule from all of my new coworkers. Finally a veteran tool & die maker told me the problem was the blade welder on that particular saw and that I needed to weld the blades on another machine. But I was not told until I was properly humbled. Sort of an initiation  I guess.

User Rank
Txema   2/22/2012 9:33:43 AM
I never thought of a case of unstable control by switching the remotes of HVAC systems... really funny!

Next time you need some cooling, try to roast your neighbour!!! -lol-

Page 1/2  >  >>

Partner Zone
Latest Analysis
Advertised as the "Most Powerful Tablet Under $100," the Kindle Fire HD 6 was too tempting for the team at iFixit to pass up. Join us to find out if inexpensive means cheap, irreparable, or just down right economical. It's teardown time!
The first photos made with a 3D-printed telescope are here and they're not as fuzzy as you might expect. A team from the University of Sheffield beat NASA to the goal. The photos of the Moon were made with a reflecting telescope that cost the research team 100 to make (about $161 US).
At Medical Design & Manufacturing Midwest, Joe Wascow told Design News how Optimal Design prototyped a machine that captures the wing-beat of a duck.
The increased adoption of wireless technology for mission-critical applications has revved up the global market for dynamic electronic general purpose (GP) test equipment. As the link between cloud networks and devices -- smartphones, tablets, and notebooks -- results in more complex devices under test, the demand for radio frequency test equipment is starting to intensify.
Much of the research on lithium-ion batteries is focused on how to make the batteries charge more quickly and last longer than they currently do, work that would significantly improve the experience of mobile device users, as well EV and hybrid car drivers. Researchers in Singapore have come up with what seems like the best solution so far -- a battery that can recharge itself in mere minutes and has a potential lifespan of 20 years.
Design News Webinar Series
10/7/2014 8:00 a.m. California / 11:00 a.m. New York
9/25/2014 11:00 a.m. California / 2:00 p.m. New York
9/10/2014 11:00 a.m. California / 2:00 p.m. New York
7/23/2014 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Oct 20 - 24, How to Design & Build an Embedded Web Server: An Embedded TCP/IP Tutorial
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6

Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Next Class: 10/28-10/30 11:00 AM
Sponsored by Stratasys
Next Class: 10/28-10/30 2:00 PM
Sponsored by Gates Corporation
Next Class: 11/11-11/13 2:00 PM
Sponsored by Littelfuse
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service