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Made by Monkeys

Unforeseeable Failure of Logic in Washing Machine Manual

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S.Wimmer
User Rank
Silver
Wrong problem
S.Wimmer   6/2/2014 9:37:00 AM
The problem was not filling not that it wasn't agitating.

You were chasing the wrong problem (been there done that).

Always check for the real problem yourself.

GTOlover
User Rank
Platinum
Re: Wrong problem
GTOlover   6/2/2014 10:31:44 AM
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Seems more and more the manuals are lacking. The appliances get cheaper and the manuals get thinner!

bob from maine
User Rank
Platinum
Re: Wrong problem
bob from maine   6/2/2014 10:41:03 AM
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I guess as the controls are intergrated into fewer and fewer components, the necessary manuals become thinner. Soon the manual will be printed on the power cord: "If this device doesn't work, open the back, disconnect the power cord, replace the device and reconnect cord". Kind of like a PC.

Cabe Atwell
User Rank
Blogger
Re: Wrong problem
Cabe Atwell   6/3/2014 7:51:21 PM
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I agree, the manual I got for my new programmable thermostat is one page long. I guess when it comes to the devices programming features I should just 'know' how to do it.

OLD_CURMUDGEON
User Rank
Platinum
Re: Wrong problem
OLD_CURMUDGEON   6/17/2014 3:38:53 PM
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Seems to me Cabe that you've hit the nail on the head, BUT not just with your "smart" thermostat.  I think this trend started a while ago as application software on PCs got to be more sophisticated, all-encompassing, and all-powerful.  The producers decided it was far easier to pack HELP files full of "stuff" and to invent the ubiquitous, but despised acronym, FAQ!!!!  No matter how complete these HELP files think they are, most often what you need cannot be isolated easily, OR it was not there to begin with.  And, FAQs are just as despicable.  A person has to wade through a literal mountain of questions to find something close to the answer being searched for.  Personally, I get a charge from some MICROSOFT websites... down at the bottom is the question, "Was this information helpful?"  How many times I wanted to throw my shoe at the PC screen, I can't begin to count!!!!!

I HATE WINDOWS and EVERYTHING It stands for!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

JimT@Future-Product-Innovations
User Rank
Blogger
Re: Wrong problem
JimT@Future-Product-Innovations   6/18/2014 12:01:33 PM
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Bob, that's funny. "disconnect the power cord, replace the device and reconnect cord".

JimT@Future-Product-Innovations
User Rank
Blogger
Re: Wrong problem
JimT@Future-Product-Innovations   6/18/2014 11:56:07 AM
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I don't have any problems with the manuals getting thinner; less paper wasted in the first place.  Hate to sound arrogant, but most manuals are not written by the design engineers, and the design-intent is never well-communicated.  The tech-publications team is (most times) not an engineering staff and they don't convey the clearest messages. (insert tab-A into slot-B. Gimme a break!) That being said, I repair all my own appliances, and found this web site to be the best work-partner you can have.

http://www.repairclinic.com/

Repair-Clinic.com, out of Canton MI, offers parts (with photos) and instructional videos for every brand of every type of appliance, and offers full returns of all parts (even electrical) up to 365 days after purchase,  no questions asked.  I have used them again and again (Washer, dryer, Stove, Microwave, DW, disposal) and cannot praise them enough! (I sound like a salesman.  But they are worthy.)

Mr. Fixer
User Rank
Iron
Re: Wrong problem
Mr. Fixer   6/4/2014 8:06:34 PM
Oh it was agitating, agitating the owners!  

These days, many of the components of an appliance have markings that indicate what material they are made from, so they can be recycled.  To me, the ultimate in recycling is repairing the appliance and continuing to use it.  That is getting to be more and more difficult with every product cycle, for the very reasons we all read about in "Made by Monkeys".

jtcronin
User Rank
Iron
A great story, thanks.
jtcronin   6/17/2014 3:45:35 PM
Modern washers and dryers are a great example of decades of optimization.  They have a number of sensors that often serve several roles.  How they can affect the operation of the appliance is often not obvious.  My compliments to your diagnostic skills and persistence.

Many years ago when I designed machines and used PLC's to control them we had very similar problems.  A faulty sensor could trip an important safety interlock.  Finding which sensor could be tedious.  

One day inspiration struck.  We were at our favorite watering hole debating a design on some cocktail napkins.  We looked over and saw a repairman working on the establishments pinball machine.  Inside that pinball machine was a single board computer that worked very much like our PLC's.  It had a diagnostic mode.  In that mode you could check and test ever sensor and actuator.  Stepping through the diagnostics the technician quickly found a microswitch behind a bumper was mis-reading.  Its bracket was bent.  With a little bit of finger pressure he was able to reposition it.  With a few drops of glue he was able to secure it better.  

In about 15 minutes that repairman was able to diagnose and fix a machine as complicated as ours.  It took us hours to do the same thing, and we needed a mountain of drawings too.  

Why don't we put in a diagnostic mode program in our PLC systems?  

We did and the folks in the factory loved us for it.  They thought we were genius miracle workers.  All we did was to borrow an idea from a pinball machine.

What troubles me is you don't see something like this in household appliances.  None of my appliances with electronic controls has any sort of diagnostic mode.  It would be trivial to include one.  

I'd bet that Whirlpool washer has a mechanical timer and control system.  Mine does.  The new one I just purchased has a mechanical timer too.  Given the low cost of microcontrollers, why does anyone still use the mechanical models?  

ab3a
User Rank
Platinum
Re: A great story, thanks.
ab3a   6/17/2014 8:35:15 PM
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+1000!

I couldn't agree more.  We have test modes for the systems we design. If a float switch, level indicator, or flow sensor goes bad, our staff have the technology to figure this out.


But for whatever reason, they don't do this for household appliances. I guess they want people to be frustrated when the repairman can't fix it right away so that they  go out and buy a new one instead of fix the existing equipment.

This is how waste happens.

Technophile
User Rank
Bronze
Re: A great story, thanks.
Technophile   6/18/2014 2:30:51 AM
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@ab3a, kudos for putting in test modes!  I'd guess that test modes pay off immediately during product development.

For appliances, it seems to me that companies either respond to the market or lose market share.  Contractors building a furnished house:  I'm guesing most buy on price.  Many (most?) consumers buy appliances based primarily on price (some using e.g. Consumer Reports ratings), so corporations have to keep the price down if they want to sell appliances.  Other consumers buy based on bells & whistles or plan to move every few years; they aren't interested in keeping their washer running for 30 years.  If companies spend money making appliances more maintainable, that's an up-front expense.  How do you justify that to management?  How does management justify that to shareholders?

This is in contrast to production lines, where I'd think engineers are usually picking machinery to last, and are (hopefully) well aware that avoiding down-time is worth spending more. 

Perhaps some consumer education, or a "Repairability" rating.  The more consumers buy based on repairability, the more companies will focus on it.  Could be sold as part of a "green" rating.

When a company is building 100,000+ of something, every penny gets shaved.  $0.01 x 100,000 = $1,000.  $1.00 x 100,000 = $100,000.  It's easy for management to see the immediate, up-front benefit of shaving pennies.   Harder to convince them to spend on maintainability unless it clearly and obviously will sell many more appliances.

Frogman842
User Rank
Iron
Re: A great story, thanks.
Frogman842   6/18/2014 3:02:18 PM
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My Fisher and Paykel washer, dryer and dishwasher have excellent troubleshooting guides and modes. 

You can exercise all the valves, lights and motors, test the switches and read the sensors. All from the front panel display.

My wife's washer had a problem that was easy to diagnose - AND REPAIR. The offending sump pump had a decent connector for the motor and the assembly twisted out by hand with a coarse threaded fitting. And the part was not expensive or hard to find.

Well done. They have me as a customer for life.

David

fdos
User Rank
Iron
Re: A great story, thanks.
fdos   6/23/2014 1:27:34 AM
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@frogman: I need some advice from you on the dishwasher. Im kind of confused on how do they clean each and every dish without damaging it ? According to my knowledge the dishes do need to rotate properly to clean it entirely. So how can this work without clashing with each other. 

Frogman842
User Rank
Iron
Re: A great story, thanks.
Frogman842   6/24/2014 1:43:19 PM
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@fdos-

Plastic dishes!

Larry M
User Rank
Platinum
Another washing machine debug
Larry M   6/22/2014 8:49:13 PM
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(This should really be a Sherlock Ohms submission.)

I'm still using the washing machine my late wife and I bought in 1984. It was one of the first ones with solid-state control. We selected it because we were tired of repeated failures with mechanical timers. Either the motor or contacts would fail and replacements were outrageously expensive. (GE/Hotpoint had come up with a timer with replaceable contact points by then, but the timer motor was still a weak link.)

The first problem with the washer, a Whirlpool, occured in 2007. The outer tub rusted through near the outlet and had to be replaced. After I did so, the machine failed to operate properly. It would start, fill, and then agitate continuously, never proceeding to a spin (and pump), fill, rinse, and subsequent cycles.

The electronic control was straightforward with pin-through-hole construction. It had what looked like an 8041 microcontroller with sensor inputs (door, water level sensor NO and NC contacts) and outputs which drove the machine (motor on/off, two solenoids on the transmission) through simple diac/triac circuits. All the components and circuits were clearly silk-screened on the board and Whirlpool had helpfully provided an inserted pamphlet with a block diagram.

I first discovered that I could turn the washer off, and then start it in the spin cycle and it would properly empty the machine of water. I also discovered that if I let the machine fill and agitate beyond the expected time and then removed the pressure hose from the water level sensor, that the machine would continue on to spin, the next cycle portion.

Consultation with the experts on the forums gave only the following unhelpful information:
  • It could be either the water level sensor ($50 or so) or the controller board ($350)
  • Both components were no longer available

so I knew I would have to figure it out myself.

Now the problem with debugging with an electronic timer rather than a manual one is that the only way to advance the timer is to wait for it--there's no knob to rotate. So after some head-scratching I decided to follow the awful and hard-to-read timing chart on the back of the washing machine.

I chose to trace the Gentle cycle because the wash cycle was only eight minutes; the other two were twelve and fourteen minutes. It was fortuitous that I did so.

Crouching behind the washing machine studying the timing chart and watching the works as it filled, then the water level sensor caused the microcontroller to start the agitator as the motor ran at the slower, gentle speed. After eight minutes the motor suddenly advanced to the faster speed as agitation continued. This told me that the microcontroller was working. After thinking about it for a bit, I disconnected the water level sensor hose and the drum began to spin as water was pumped out. But the timing chart said the water was to be pumped out and then spin would begin.

Time for more thinking. The transmission has two solenoids. That means it has three or four states. The identified states are:
  1. Agitate (no pump, no spin)
  2. Pump
  3. Spin and pump

The state was never changing from Agitate to Pump. Watching the solenoids as I went through the sequences of Off-->Spin and the long Off-->fill-->Agitate-->Pump let me identify that the Agitate solenoid wasn't releasing at the end of the wash portion of the cycle. I poked at it and determined that it was still energized. When turned off, it moved freely so it wasn't mechanically stuck. And now the problem became very simple.

Early in my career I had worked for a few years in reliability physics and one of the components I had evaluated was SCRs. Triacs are similar to SCRs. One of their well-known failure modes is latch-up. When an SCR or Triac suffered this failure it would remain off when biased (as it should), and turn on when triggered (as it should), but it would not turn off at the next zero-crossing when the trigger was removed (as it was supposed to).

And this was exactly what was happening. The triac turned on for the agitation and wouldn't turn off to shift the transmission so the pump would run. The microcontroller was waiting (forever) for the non-running pump to drain the tub. If I removed the sensor hose, the controller would start the pump running and spin while there was still water in the tub, instead of pumping without spinning until the tub was empty, then spinning. If I turned the machine completely off and then started it directly in the spin cycle, the Agitate triac was never triggered so the pump worked fine.

Of course the original triac part number was nowhere to be had, but I was able to order a triac with the same case and pinout from Mouser Electronics. They had units rated at 110v for 35 cents, 220v for 36 cents, and 440v for 37 cents. I thought the higher breakdown voltage might reflect a more reliable part so I splurged on the expensive one. 

It took just a few minutes to unsolder the defective triac and install the new one and the washer has worked fine ever since. I did let the forum experts know that the washer had been fixed for 37 cents, but never received a response. I guess they were more expert at replacing modules than working at the component level.

a.saji
User Rank
Silver
Re: Another washing machine debug
a.saji   6/23/2014 5:08:01 AM
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@LarryM: Good set of points mate. I think they are only concentrating on replacing rather than repairing because of the cost I guess. 

tekochip
User Rank
Platinum
Re: Another washing machine debug
tekochip   6/24/2014 2:29:45 PM
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I wrote code for a few washing machines, and the ones I was involved with all had detailed specifications for diagnostics that actually took up as much code space as the run time for the machine.  All of the code was designed to pinpoint a failed device or wiring, but the control itself was treated as a black box.  If there was anything wrong on the board it would be replaced as a single component.  I really can't blame the manufacturers for this, because the days of appliance repair technicians coming into your home with a soldering iron and an oscilloscope are long, long gone.


Larry M
User Rank
Platinum
Re: Another washing machine debug
Larry M   6/25/2014 9:58:54 PM
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Tekochip wrote: "All of the code was designed to pinpoint a failed device or wiring, but the control itself was treated as a black box.  If there was anything wrong on the board it would be replaced as a single component.  I really can't blame the manufacturers for this, because the days of appliance repair technicians coming into your home with a soldering iron and an oscilloscope are long, long gone."

I actually did look for a replacement board. I didn't start this deep level of debugging until I learned that the boards were no longer available. Given that I had had good service from the washer and had just replaced the outer drum, I felt driven to make it work again. Yes, I probably invested 4-5 hours debugging over five days and 10 or 15 minutes effecting the repair, but it was worth it.

I can't see a service guy doing this sort of thing in any of the last four or five decades, but in the 1950s I was very impressed by my Scoutmaster, an IBM CE. He told stories of failures in assemblies where the customer desparately needed the machine and no replacements were locally availalble. He went to a nearby Radio-TV repair shop and got discrete resistors and capacitors to replace the failed unit and got the customer going again. I could do no less.

Did you know that I just retired from IBM after 45 years of service?

timbalionguy
User Rank
Gold
Re: Another washing machine debug
timbalionguy   6/25/2014 9:30:27 PM
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Larry M, that was definitely worth the long read. I have never seen a triac fail like that, but I will certainly remember this one for the future.

My washer and dryer, dating from early 2002, still use mechanical timers, and in the case of the dryer, a simple moisture sensor circuit. They have never given me any problems, and if they do, they are simple to troubleshoot. If I have to replace these appliances someday, I hope the new ones will be as simple.

I occasionally visit a friend of mine in another part of the State to take care of their animals while they travel. They do this frequently enough (plus like to entertain guests) that they built a really nice apartment for me to stay in while visiting. They splurged ina put in state-of-the-art appliances. No more simple wash/dry cycles. these beasts are so complex in what they do that it boggles the imagination. I have atually enjoyed watching them go through the machinations they do to wash and dry clothes (and the dishwasher is even worse!). I will have to say though, they do a superb job.

Larry M
User Rank
Platinum
Re: Another washing machine debug
Larry M   6/25/2014 10:03:36 PM
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timbalionguy wrote: "I have never seen a triac fail like that, but I will certainly remember this one for the future."

Things have changed a little since 1984 when that washer was built. Products like IGBTs are used now, and even SCRs and Triacs are more robust than they used to be, with more isolation trenches, etc., to eliminate the parasitic devices formed when you try to build a PNPN device on a substrate.

I haven't done component reliability work for since 1975, so it wouldn't surprise me to learn that this failure mode really is a thing of the past--like the washing machine.

wbswenberg
User Rank
Platinum
Trouble Shooting
wbswenberg   7/9/2014 6:51:15 PM
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I like to watch the thing work also.  I think about what it does and what it does not do.  The neighbor had a problem with his dryer.  Looking at the block schematic was very cryptic.  I like to jump around the problem depending on normal open vs closed.  We jumped around sensor and the dryer work.  So we knew what the problem was.  He surprised me and found the part and replaced it within a couple of hours.

Same with his furnace.  When we got it to work we knew were the bad part was.  The furnace tech just could not spent time with it.  Good training for me cause then mine failed.  It was a bit faster cause I was familiar with the circuit.  

William K.
User Rank
Platinum
Troubleshooting without the manual
William K.   7/24/2014 4:55:43 PM
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The best way to diagnose a machine failure is by understanding how the machine is supposed to work. So if the problem is that the fill valve is not opening the first step is to check and see if it is being asked to open. Checking voltage across a solonoid valve is not hard, and either the voltage is correct or it is not. If voltage is present and the valve does not open then placing a screwdriver near the coil will tell if it is operational. Voltage present but no magnetism is a symptom of an open coil. An ohmmeter check with the power off verifies the failure as an open coil. And no matter what the manual claims, I would suspect a valve coil before a water level sensor.

Nuvistor
User Rank
Iron
Self Test
Nuvistor   8/12/2014 1:37:46 PM
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I remember when I used to work on some of the first solid state Whirl Pool and Kitchen Aid washers a long time ago. The control PCB had a two pin connector on it. If you momentarily shorterd the pins together, the machine would go into test mode: First the cold water valve would open for a few seconds and then shut off. The hot water valve would do the same thing. Then it would adjatate for a few seconds and then pause (Neutral drain before spin). Finally, it would spin. This would run the machine through the paces and you could easily see which output did not work. I am not sure if Whirl Pool still does this but it was a very usefull test. If a fill valve fails, it is a good idea to check the inlet screen and hose screen since they are the first to clog before the valve fails.

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