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Elizabeth M
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Re: Design questions
Elizabeth M   7/10/2013 4:51:03 AM
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Thanks for that real-world perspective, Analog Bill. I am not surprised the manufacturers act that way but it is a bit disheartening. You'd think they'd want advice on how their products could be improved and even potentially be less dangerous to consumers.

J. Niiranen from ABB
User Rank
Iron
Re: Design questions
J. Niiranen from ABB   7/10/2013 3:07:02 AM
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Dear Rob Siegel, this fridge capacitor issue does not make a good Made by Monkeys case because it is difficult to say who to blame.

The capacitor has 275 V AC rating according to the photograph and thus it should be OK for 230 V supply. Thus most likely the reason has been either wrong labeling of the capacitors, defect in manufacturing of the capacitors or even fault in the manufacturing process of the metallized foil.

According to the discussion forums the problems started around 2005 typically after 2-3 years of operation and thus this kind of failure mechanism is difficult to find at factory testing even if you do some acceleration testing.

The problem with these kind of slowly developing faults is that quite a many products have been made before there is any indication that something is wrong.

Good question is if the faulty capacitors could have been detected by overvoltage testing of them.

Naturally it would be nice to hear what was the actual reason for the problem.

By the way, regarding capacitors and possibly related with this, it may not be a well known fact that "Y" RFI capacitors are designed to fail to open circuit due to safety reasons (short circuit would make the chassis under line voltage) and thus it is typical that these lose gradually their capacitance. Thus it may be that old equipment does not anymore fulfill the radio frequency emission limits.

 

Charles Murray
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Blogger
Re: Design questions
Charles Murray   7/9/2013 6:59:33 PM
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One more point about the "top secret" mentality, Analog Bill. Over the past 25 years, I've learned that I can get a quick callback from most automakers when I call with a question. Not so with appliance makers. Usually, I run into dead ends and unreturned calls.

Charles Murray
User Rank
Blogger
Re: Design questions
Charles Murray   7/9/2013 6:56:11 PM
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Thanks for the input, Analog Bill. It's disappointing to hear that the manufacturer's designers are often so reticent to respond. But the top secret mentality has always been there among appliance manufacturers. We've seen it repeatedly in the press. So, yes, it's disappointing but not surprising.  

Rob Spiegel
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Blogger
Re: Design questions
Rob Spiegel   7/9/2013 3:21:40 PM
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Hey J. Niiranen. Your reference to problems you've seen would make a good Made by Monkeys blog. Please write it up and send it along to: rob.spiegel@ubm.com

Analog Bill
User Rank
Gold
Re: Design questions
Analog Bill   7/9/2013 12:16:44 PM
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Based on my experiences, I wouldn't hold my breath waiting to hear from the designers!  I'm an (analog) electronic circuit designer and do a lot of teaching via trade-show seminars and writing (was even an invited lecturer at MIT in 2007). My company specializes in solving signal interface noise issues (hum and buzz in audio or "hum bars" in video) and, as a result, I end up talking technicians through troubleshooting steps to identify and fix the problem. Many times, the problem is due to a design defect in the equipment. If I call the equipment manufacturer to get more information or point out a design issue, it is *extremely* difficult to actually get to the designer. Sometimes, I have to actually create a partial schematic of the product myself (manufacturers often treat the simplest "me-too" designs as if they were top secret). Since they won't lift a finger to help ... I then use their faulty design as an example in my seminars (as a "don't do this") and I identify the make and model. Students love this honesty but, when word reaches the manufacturer, the reaction is very different. Usually, the threatening e-mail comes first ... whereupon I remind them that I tried to enlist their cooperation but they refused and that it's not libel unless the information I spread is false, whereupon I challenge them to refute any of the facts ... and call off your lawyers. A few times, I've been visited by the company's PR and marketing folks (acting a bit like a "goon squad") to intimidate me to shut up. I tell them I'll happily spread the word that the problem is fixed ... if they're willing to be part of the solution rather than the cover-up. It doesn't always work, but I find public embarrassment to be a powerful tool. I can recall only two cases where the manufacturer not only supplied my requested inforrmation, but actually implemented the design change I suggested ... and sent me one of their power amplifiers as a "thank you" gift!  The company is Rotel, by the way.  - Bill Whitlock, president & chief engineer, Jensen Transformers, Life Fellow of the Audio Engineering Society, Life Senior of the IEEE

J. Niiranen from ABB
User Rank
Iron
Re: Design questions
J. Niiranen from ABB   7/9/2013 8:55:03 AM
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Interesting to hear about the capacitor problem. Is this the same issue that there was with several brand refrigerator/freezers? The power supply of the electronics was apparently done by capacitive divider. The film capacitor lost gradually its capacitance (self healing action due to transients or faulty lot) until it was so small that the electronics started to work intermittenly manifesting itself by the lamp blinking (thus causing the syndrome to be called as disco syndrome).

Because of the number of these incidents and the high price of the replacemet control board there is a DIY instructions how to change the capacitor:

http://www.elisanet.fi/mtj/santo/AEG-Santo-fix.html

Elizabeth M
User Rank
Blogger
Re: Design questions
Elizabeth M   7/9/2013 3:58:32 AM
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Yes, Chuck, I'm thinking the idea to hear from the manufacturers on some of these design-flaw issues is not just a great idea, but almost becoming necessary. People spend a lot of money on products and we are meant to trust that the people designing them know better than we do how to make a solid project. With all the consumer fixes we see in Design News columns, it's clear that many times this isn't true. There needs to be some accountability, I think.

Charles Murray
User Rank
Blogger
Re: Design questions
Charles Murray   7/8/2013 7:10:56 PM
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I agree, Liz. The design group should know better and maybe they do. As you correctly point out, this is another case where we need to hear from the manufacturer.

tekochip
User Rank
Platinum
Re: Design questions
tekochip   7/8/2013 5:09:08 PM
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The Calypso was a nightmare.  I tried to hang onto mine, I figured since I didn't pay for it, I could afford a few repairs.  First the level sensor went.  Then there was a huge problem with the suds lock sensor on the pump.  Some pumps worked, some pumps didn't even though there wasn't really anything wrong with the pump.  Then the transmission would get grease all over your clothes, and that was a big issue.  Finally, the transmission in mine failed, so I bought a new machine. 
 
This machine also has the cute change cup to catch foreign material like coins before they eat the pump (sometimes guitar picks, too), but you have to take the machine half apart to get to the cup.
 
The guys at Whirlpool tried to make a nice machine with unique features, but they really over-engineered the machine and then rushed it to market without fully testing it- probably because the project had already taken so long to develop.


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