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  Electronic Controllers

People often assume the worst and the controller is faulty but that's often not correct

 

Before you read this article let us point out that we are no electronics or programming gurus, have not a single qualification in the area but we do understand how many electronic devices work and how programming works. Therefore this is not intended as a definitive guide to all things electronic with washing machines, dishwashers and so on but more as a "how to think about it logically" guide.

The reason is that many people have the notion that, whenever an appliance (especially washing machines) do anything that is a bit odd or unusual that the "controller" has to be faulty and, all too often, that simply is not the case.

What is much, much more common (probably over 90%+ of the time) is that the diagnosis of the fault is incorrect, if there even was one to begin with.

We see so many people, both general public and professional engineers on occasion (although a lot less obviously) that blindly assume a board fault when it's nothing of the sort. This can prove a very expensive and inconvenient guessing game if you don't know what you're doing.

  Electronic Control Boards

An electronic controller in a Beko dishwasherThe first thing that many people have to understand is that most electronic boards will almost always do one of two things, work or, not work.

What we mean by that is that there usually isn't any in between with them, they don't go flaky usually, don't go into a huff and decide not to do certain things at certain times and so on.

To explain that, most boards used in domestic appliances are, in the grand scheme of things electronic, pretty darned simple affairs with proven, robust components soldered onto a PCB. The programs are, equally if not more simple especially when compared to even the simplest mobile phone that we all carry about with us.

They are a simple collection of relays and switches mounted on a mass produced board.

These relays and switches either work or they don't in the main. Sure, you can get a sticky relay or switch but it is incredibly rare. They will sometimes burn out as well and, when that happens, it is often either the relay, switch or whatever it controls that is the problem.

You can see physical damage if tracks lift on the board.

The only oddball thing you get is the odd dry soldered joint but a trained person will usually (or often) spot that.

With all appliance control boards, when compared to a PC fro example, they are positively prehistoric. Almost none would even have the power of a humble x386 PC from the 1990s, if they even have the power of a generation or two back from that.

The only real difference from a true "solid state" device is that you have the relays and perhaps a couple or so switches on the board and little else. In other words, the most likely point of failure is, as usual, the moving mechanical elements or connections and not the actual PCB or EEPROM.

  The Software

Appliance electronics aren't all that smart really, they're really quite dumb in many ways only intended to repeat the same task over and over

Most appliance control boards are so, so simple in many ways and all I've come across have their programs stored in an EEPROM, which is known as non-volatile memory and, in the practical terms, barring a hammer or other physical damage, a strong magnet or an EMP, you cannot damage or alter the programming, ever.

So what happens is that the program (which you can't alter remember) sends signals to switch on or off relays based on the program selected and the conditions read from other components or "sensors". These readings tell the board what to do when.

The programs are robust and, if they go faulty then you've either blown the EEPROM in some way or physically damaged somehow or, there's been a local EMP that took it out, the most common cause of which is a nuclear detonation. In which case, the least of your worries is a faulty washing machine or dishwasher.

The point being that, the programs don't change. They don't degrade over time. They cannot be altered without some sort of interference or reason.

Therefore, if you think that is what's happening to your washing machine, think again. It isn't.

  Most Common Mistakes Diagnosing Electronics

Now you know that boards are pretty robust and don't fail for the reasons that many people assume that they do here is the common things we see often causing the problems seen.

  • Other component failure
  • User error
  • Wiring or connector fault
  • Earth fault

Please understand that we are not advising that whatever the problem may be will not be the control board but, in tests, over 70% of the boards that come back for inspection have no fault.

The odds are pretty good that the fault will be caused by one of the above and not the electronic control board.

This is from both amateur and professionals trying to repair and the reason most often is that people "assume" rather than "prove" where the fault is. 

Electronic control boards are invariably expensive, they are not a thing that you want to be replacing on a whim as it can prove both futile and costly.

Let's look at each area a little more.

  Component Failure

The most common cause of a misdiagnosis when it comes to electronic control boards or timers.

These days, especially for washing machines, fridge freezers and dishwashers, a lot of low voltage "sensors" are used to detect the current conditions that the machine is encountering. So, for example, until the water temperature is reached which is "sensed" by a simple thermistor using a resistance value, the wash cycle will not progress.

Equally though, if the board gets an invalid or out of range signal from that (or any other) component it can do one of two things in the main, it shuts down and will often report an error in the form of an error code or fault code. Or, it just goes wackadoodle and does all manners of weird and wonderful stuff.

One very common cause for this is leakage onto these sensors either directly or from condensation causing an invalid resistance to be reported to the PCB and, presto, instant fault that many people won't understand.

Engineer arrive a few days later, replaces the PCB and it all works again. Replacing the PCB did squat to fix the fault but, it did allow time for the moisture to evaporate.

Always, always check for simple things like this and check the other components are all okay.

  User Error

Yes, users make mistakes, hence the term, "RTFM", it applies just as equally to appliances as it does to many other things we come across in life.

Washing machines are the worst for this but, it happens on other appliances on occasion as well. 

We get the "It doesn't work on…", "It does this but, only on the XXXX program…" and so on and you can pretty much guarantee that in a high number of instances there's not a thing wrong with the machine.

When you use any appliance there are variable involved, the more variables, the more chance that something will not be gotten right by the users. Let us demonstrate with a washing machine list of variable that are all completely controlled by users, not the machine or anything else.

  • The wash load size
  • Wash load content
  • Wash load colouring
  • Type of detergent used
  • Amount of detergent used
  • Program selected

And, that's our list trimmed right down!

We didn't go into the water pressure, water quality, drainage and a heap of other stuff that, to be blunt, most people just don't care about or ever stop to think of. Until they have a problem of course, then the machine is often blamed for whatever when, these variables are usually completely beyond anyone's control other than the actual user.

A good example and, one that is very common, is the complaint about wools shrinking in the wash. Well, if you don't use the specific detergent that you can buy for wool then yes, that will happen and if it doesn't then you've been lucky.

What often happens is an engineer gets called because there's a "fault" or the customer replaces the controller because they think that the machine is overheating, but only on a wool program. Wrongly obviously because, if the machine heats okay on every other program okay then the board is fine given it uses the same logic, EEPROM, heater and thermistor to do the same thing, albeit at a different temperature, on every other program.

And, we've seen engineers spend hours trying to chase down these "non-faults", often simply because people won't own up to perhaps not following the instructions and insisting that they made no errors. But it is difficult for an engineer to explain that you're doing something wrong, often in the face of comments like, "I've been doing this for years…"

  Wiring And Connector Faults

We see on a regular basis people replacing electronic control boards because the appliance is doing something "odd" or uncharacteristic but the fault is either not resolved or, it reappears some time later.

It is known that the mere act of pulling the connection off the board and remaking them (with a new one!!) sorts the problem on occasion. Well, a number of occasions if the truth be told.

As we explained above, anything that causes the electronic controller to get an incorrect, invalid, out of range or errant signal (including excessive noise on the mains) can cause a fault. Therefore, dirt, detritus, moisture and so on being in one of the connector blocks or terminals can (and does) cause strange errors to occur.

It is very worthwhile checking all connections when you suspect that the board is okay.

  Earth Faults

You should now know that any fault on the mains can and will cause electronic controls to report errors, shut down or go off the rails. Well, any fault allowing the mains or even sometimes low voltage components to track to earth will also cause them to do so.

Once again, you need to check if there isn't an obvious cause of the fault evident.

  Error Codes

Error codes or fault codes are used to help in diagnosing problems, there's plenty of information on the site about them already so we'll just cut to the chase here.

Control panel on a Samsung washing machineIf a machine reports an error code then it is trying to point you in the direction of the fault to resolve it. They're not that smart really and only serve as a help to diagnose the problem, they don't pinpoint it for you but, if you get one, chances are the electronic controller is absolutely fine and it's just doing its job as that is exactly what it was designed to do. Report a fault and the general nature of the issue or fault encountered.

These boards are designed with logic that runs along the lines of, "Water not getting hot enough in twenty minutes … Report fault code F5 …. Drain … Abort cycle"

They are really that dumb.

They don't usually deal with even the likes of simple conditional programming like If/Then/Else, all they know is that they either work or they don't. They operate within the preset parameters or, they don't.

However that simplicity also serves to make appliance electronics generally incredibly robust both in terms of both hardware and software. There's actually not that much to go wrong.

So in reality, appliance electronics are actually pretty good and solid. Given the nature of them and the intended use as well as audience and, that's a good thing.

Of course, like everything else in life, the cheap ones, not so good and there is a large dollop of, you get what you pay for, in there.

If you buy cheap you get cheap rubbish connectors, cheap wiring looms, cheap electronic components that are built to a price and so on but, as the customer. That's your call and that largely comes back down to the owner's choice just as it is where you choose the cheap car over the expensive better built one, the cheap meal over the more expensive and higher quality one.

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