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Old 24th November 2004, 10:45 PM   #1
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Default Engineering quality

I just finished a repair job on my household appliances, namely a Blomberg wash machine and a Gorenje tumble dryer.

After this i can only conclude that we are expecting a much higher level of engineering quality from the audio industry than found (at least) in these household appliances. Some of the technical solutions in these machines are shockingly unreliable seen from the viewpoint of an engineer in the audio industry.

I will list a few.

The problem started when a small coin was stuck in the output filter of the wash machine. So all the water could not exit, and subsequently the clothes was not completely centrifuged. The clothes were nevertheless moved to the tumble dryer. Since it was now slightly heavier than fully centrifuged clothes, a belt soon snapped inside. Further a small drop of water had found it's way to the door contact of the washer.

All of the above are situations that should - in my opinion as a consumer - be regarded as normal operation conditions, and not lead to malfunctions of wash and dry machines. Maybe at most should shut the machine down with a warning signal.

If you bought an amplifier of 60 W in 8 Ohms, would you accept that it blew up in smoke the moment you connected a 6 Ohms speaker to it? I think not!

Looking at the thin solutions found inside, it is however not surprising that it fails so easily......

The door contact in the wash machine was made of a small plastic carrier, where the metal split of the door hits every time the door is closed. Now a big door with a small split the hits a plastic parts.... Not hard to imagine how short service life could be expected from that.... :-(
A bimetal bar is heated by a resistor when the power is on. The bar has double function as a switch and a mechanical blocker.
This way it can both mechanically block the door from opening when the power is on, and also send an electric signal to the mechanical program wheel (yes it is a machine from 2003 not 1953), that the door is securely locked. The problem is that a droplet of water shorted the resistor to the switch and flashed out the connection from the program wheel. I repaired the broken connection, but soon the bimetal bar could not make a connection because of calcium from the water droplet. Now how could the engineers have foreseen that a drop of water could find it's way into the door contact of a washing machine ???? Hmmm .... Yes it's a big challenge!

How they still make these machines with mechanical program wheels is really a mystery to me. Even a nice microprocessor with a bunch of small operation switches must be a lot cheaper. And much more reliable. But it appears the engineers are insisting on keeping all control systems running at 230 V and NOT 5V .... Maybe they are electricians and don't want to give their job to an electronics guy ??

A good solution for the door contact would be a waterproof optical sensor fork (costing less than 50 cents) signalling to a microcontroller, that controls the whole machine. The door could be mechanically blocked by a magnetic actuator or even the very same small motor they always insist on using to drive the program wheel. It should - of course - be placed somewhere without water. (Somehow i feel it needs be said....)

Now the tumble dryer is even worse! Again a 230V mechanical timer with a small motor and neon bulbs. No LED's no micro processor timer, no monitoring of the drum. The bearings for the drum are made of carpet, (The drum itself is sliding on the carpet ....!)
And it is driven by a tiny belt running around the drum, taking it's torque directly on the 8 mm diameter electric motor hub - the same motor that drives the fan. No wonder this will fail the instant any operating condition is slightly less than perfect. Unbelieveable! A simple drive wheel for the belt would improve the reliability significantly, but then probably cost 50 cents more.
To replace the belt you will have to disassemble the entire machine, before you can fit a new belt and put it back together. If you were a housewife, and not a DIY geek like me, you would have to pay several hundred dollars for the repair job, more than a new tumble dryer cost.

Now that is what i call poor engineering quality.

A good solution would be to have the drum roll on pulleys, so a bearing is not necessary, and there is no belt that can snap. Also a monitoring of the drum is a minimum to avoid destruction or even fire in case a consumer does something slightly wrong.

I am not sure if what i found is the general low level of enginuity found in household appliances, but i think the producers of this kind of products could learn a lot from the much higher level of engineering quality found in the audio industry.
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Old 24th November 2004, 11:02 PM   #2
Cobra2 is offline Cobra2  Norway
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Talking Been there, done that.....too!

Please include vacuum-cleaners....
- and ink-jet printers!

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Old 24th November 2004, 11:11 PM   #3
SY is offline SY  United States
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Higher level of engineering quality? Tell that to the Jadis owner who watched the smoke curls emanating from under the chassis. Or the guy whose CD player laser pooped out the day after the warranty expired (that would be me!). Or the guy who just paid $10,000 for an amp with 10% distortion, an output impedance that's both high and nonlinear, an efficiency somewhere between laughable and ridiculous, and that requires a $500 set of tubes every few months which can only be adjusted by an authorized dealer for an additional $150.

As with everything else, the quality of engineering in audio follows Sturgeon's Law ("95% of everything is #@&%"). At least the washers don't have magic doodads that align the phase of the electrons going to the motor.
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Old 25th November 2004, 12:04 AM   #4
roibm is offline roibm  Romania
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Originally posted by SY
At least the washers don't have magic doodads that align the phase of the electrons going to the motor.
So I guess you never tuned your washer using some BGs, right?
You won't believe what you missed. I did the tweak and my clothes are much much cleaner now. You see, those clever electron flows are much better aligned now, as a result the motor spins without any hick-up now and you see... my clothes are just like new... Sure you can't see from there, but you can show up here if you want to(but I won't wash your undies )
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Old 25th November 2004, 12:17 AM   #5
SY is offline SY  United States
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Actually, there were some items called laundry Balls marketed here for a while. They were claimed to do exactly what you said, and even eliminate the need for soap!

Needless to say, they got shut down. That didn't stop lots of people from believing that this miracle laundry product worked.

Transylvania is a long, long way to go just to have my undies scrubbed.
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Old 25th November 2004, 01:28 AM   #6
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Having worked as an engineer for a whiteware company I can shed a little light on the subject.

Whiteware engineering is totally driven by price and marketing - engineering excellence is way down on the priority list, much to the frustration of those trying to design good product. Of course its the engineers who get the blame when the warranty returns start to come in, despite the fact that it was the bean counters that said to use the 50c part, not the $3 part.
This is not to say mistakes don't happen. I've seen things which make you say 'Damn, we should have done it this way', but by then all the moulding tools have been made and the bean counters have weighed the risk against the $500,000 re-tooling cost and decided to take the risk.

That mechanical timer is actually quite cheap, and usually exceptionally reliable. Why? Its a very mature technology - all the quirkes and bugs and reliability issues were sorted out 20 years ago, so now they roll endlessly off the production line and just work. Putting microelectronics in a wet environment is not so easy. Micros are prone to surges, lockups, interference, EMC, software bugs, and a drop of water can completely screw up 5V logic.
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Old 25th November 2004, 04:34 AM   #7
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Anybody looked at furnaces lately? Lots of electronics and metal half the gauge than 10 years ago, very sensitive to power brownouts and spikes - hell, forget about line conditioner for your stereo - you need one for the furnace to make sure you don't freeze your butt off
after power line problems.

Worst case - trailer furnaces that with propane conversiopn soot up within month - why? heatexchanger tubes way too restrictive. So - combustion gases accumulate in the chamber and cannot exhaust efficiently, so - unit soots up.
Respones from company: but it worked in the lab.
Before a new set of so called engineers started tampering, those furnaces under rough conditions - oilpatch - performed regularly for up to 20 years w/o major problems.

But believe me - i have no sympathy for guys who buy 10k$ junk like jadis - see similarly the Wavec amps that measure worse than any boombox sony ever build:
http://www.stereophile.com/amplifica...ac/index5.html
at 350k$

I buy bryston - they stand behind their products with a transferrable 20year warranty
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Old 25th November 2004, 01:09 PM   #8
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But believe me - i have no sympathy for guys who buy 10k$ junk like jadis - see similarly the Wavec amps that measure worse than any boombox sony ever build
Allow me to sincerely doubt any of them need your sympathy anyway. Especially the Wavac owners.
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Old 25th November 2004, 01:23 PM   #9
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Allow me to sincerely doubt any of them need your sympathy anyway. Especially the Wavac owners.
No, because if one buys junk at that level and really believes he/she gest anything like good engineering or anything that can even sound good - how can anybody maintain something approaching 10% distortion level can sound good when any distortion above 1% is detectable - than they also believe in voodoo and those do not need any sympathy as members of a self sustaining inner circle of the chosen illuminated.
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Old 25th November 2004, 10:22 PM   #10
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Quote:
Originally posted by roibm

So I guess you never tuned your washer using some BGs, right?
You won't believe what you missed. I did the tweak and my clothes are much much cleaner now. You see, those clever electron flows are much better aligned now, as a result the motor spins without any hick-up now and you see... my clothes are just like new... Sure you can't see from there, but you can show up here if you want to(but I won't wash your undies )

You do use a solid silver power cable too, right?


Anyway, where was the washer made? A while ago I would have made a joke about it being made in China. But they seem to be going high tech, doesnt sound like them.

The company might have picked up a surplus lot of bimetal switches for super cheap as well? Who knows.
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