Identifying cause of washing machine problem

[B.M.]

I don't know how common it is for these sensors to fail but I would have assumed the fault would have been related to what the sensor expected to pick up.

Can you test the sensor out?

To try and explain the goings on here one must realise these machines work like computers and upon power on they do a Power On Self Test. Now instead of making a series of beeps long and short they throw up a binary code with the Panel Lights. There are heaps of them, (codes that is) but a 130, tells us that the RPS Sensor isn’t responding.

Ok, I don’t believe there is a test of the Sensor that can be done in a service situation, so a replacement is the alternative, and I have no knowledge of a replacement not fixing the fault.

I’ve got one of these Sensors here that I can see a break in the printed circuit and figured I could jumper the break out. Then common sense prevailed. Too much trouble when I’ve already fitted a new one.

[Kame]

That break you mention, meant the sensor did not pick up that what it was meant to do, it is just by coincidence it was the fault but sensors normally never indicate they are at fault (depends on what they measure, cause car sensors can pick up their own faults) but the area of concern. Just like computers, if your temp sensor is high, you don't change the temp sensor thinking it's the fault unless you're positive it's reading wrong.

Since this is an RPS and the rotor has coil magnets wrapped around it, the RPS is to pick up each energised magnet through its rotation. It probably measures speed by knowing distance between each energised magnet, and not every magnet needs to be energised to control how fast or slow it spins. It should know how long the sensor would take from start position to point X, if it doesn't reach it by the time it expects it then it will indicate a problem at the RPS.

Jammed up tumbler

So for that issue, spin the tumbler by hand and make sure it doesn't jam else you'll need to find out what's jamming it and fix it.

No jams?

See if your washing machine has a test mode, since it normally beats the manual checking... see below for a few manual tests, requires a multimeter, with continuity checking but resistance reading is fine too but knowledge with electrical/electronics and sensors a big help and comes with a risk.

Anyways, at all stages, I would be physically checking components and looking for damages, nothing better than the eyeometer for these things. So be on a lookout for broken parts.

Wiring Harness

I'd look around the RPS, testing for power at the plug for the RPS, no power there, I'd check if I turned it on (seriously I would) but let's just say we are checking for power, so we know it needs to be on. If no power at the plug, that's an aha moment, so we go to the board end and check if any wires have broken away, vibration does this and hot glue helps delaying this problem, can even prevent it. So solder the wire on, glue it down and try the machine out.

Fuse

If no noticeable problem for the wiring harness, Look for fuses on the board just in case it has one and it may have blown. This should be a quick look before we go back to testing wiring harness but at this stage, you want to replace it.

Test each wire end, so board end to contact, if you find a faulty one, fix it or replace the whole harness.

RPS

So we know we have power to the plug, but we don't know if the RPS is doing it's job, now there's at least 1 more wire we never tested at the harness and may have skipped to here and that's the signal.

You can have power but the signal may not function. A broken wire or faulty sensor.

Right now, I'm just indicating things that could be faulty, but you are getting closer to the costly side of things, now changing an RPS and it fixes it, isn't costly, changing it and still the same issue, is.

BM having a broken board, maybe common? I put it down to vibration again, in which I would use rubber or foam to try to prevent reoccurrence but sometimes that's impractical but you don't want to be replacing the same parts over and over again, that's costly.

I don't know if the RPS has an indicator light, but you are at the stage where I think if you don't know what you are doing, you shouldn't be doing it.

If it has a light, great, we'd remove whatever obscures us seeing the rotor and sensor in action so we can watch it work, see where it fails.

Without a light, this is when I'd either remove the sensor and test it, connect it to a power source, put a magnet in front and see if it indicates that its sensed the magnet. If not, replace RPS.

If RPS is fine, replace rotor, not easy fixing coils and only a few specialists in NZ exist who can but you'll be better off with 2 new washing machines at their price.

I rushed this so I hope I didn't overlook the obvious.

[B.M.]

I acknowledge what you say Kame and indeed the possibilities are extensive, but the probability is almost exclusive.

Should by some chance the problem not be the RPS Sensor, then we wind up swapping out modules until we find the faulty one and the whole exercise becomes uneconomical and a new machine is the best bet.

[barryk]

I don't know how common it is for these sensors to fail but I would have assumed the fault would have been related to what the sensor expected to pick up.

Can you test the sensor out?

I thought the sensor didn’t need testing as I could see the 130 fault code shown by the LED lights in binary code and was confident that it was the sensor itself that was faulty, not the control board.

So I got the replacement sensor and had it installed in the washer with the other person’s help. I crossed my fingers when I turned the machine on and hey presto, it was working! :-)

I came across this interesting article on how a RPS works when trying to find out about how its electronics work to sense rotor position and communicate that to the control board. The article will tell you what the RPS does but not how its inside electronics work.

https://www.hunker.com/13410408/what...ashing-machine. Just substitute the words hall sensor with rotor position sensor. Don’t know why this part is called a hall sensor as I don’t know of a washer having a hall whereas a town does.

Didn’t have to buy a new washer or book in a service person.

Thanks for all your assistance with resolving this washer issue.

[zqwerty]

It's named thus for the Hall effect, see here:

https://www.google.com/search?q=hall...t=firefox-b-ab

"the production of a potential difference across an electrical conductor when a magnetic field is applied in a direction perpendicular to that of the flow of current"

[barryk]

It's named thus for the Hall effect, see here:

https://www.google.com/search?q=hall...t=firefox-b-ab

"the production of a potential difference across an electrical conductor when a magnetic field is applied in a direction perpendicular to that of the flow of current"

Thanks for explaining what a hall sensor is. Perhaps it should be more clear if it was called a hall effect sensor?

I'm still puzzled by a few things:
1) Where's the current? In the stator or the rotor?
2) Where's the electrical conductor? In the stator?
3) Is the magnetic field applied from the magnets built into the rotor?

I still don't know how the hall effect sensor picks up this potential difference or what components are inside the RPS's electronics to pick up the hall effect and communicate this information through the wiring to the controller board.

A schematics or drawing of the RPS circuitry would throw more light on this?

[Kame]

You need to understand transducers that transforms types of energy (magnetic field, pressure, etc) into another type of energy (electrical signals)

The symbol for RPS/Hall Sensor would be a variation of the transducer, box looking toast on its side with possibly the magnetic coil through it and 2 arrows pointing towards it. That's just a guess, I have no idea and it's Friday night, too lazy to see if any of them have symbols.

If at one end of a hallway is a light (magnet) with a dimmer and you (rps/hall sensor/transducer) at the other end. If its very dim it'll be harder to see, turn it up brighter and the lit area gets closer to you (increase in magnetic field). Now you shout 'turn it off' (electrical signal) and whether what you told responds to it or not is left up to the controller. But that strength in light/magnetic field, etc is picked up and converted into a signal, even the strength may alter what kind of signal it sends.

[barryk]

You need to understand transducers that transforms types of energy (magnetic field, pressure, etc) into another type of energy (electrical signals)

The symbol for RPS/Hall Sensor would be a variation of the transducer, box looking toast on its side with possibly the magnetic coil through it and 2 arrows pointing towards it. That's just a guess, I have no idea and it's Friday night, too lazy to see if any of them have symbols.

If at one end of a hallway is a light (magnet) with a dimmer and you (rps/hall sensor/transducer) at the other end. If its very dim it'll be harder to see, turn it up brighter and the lit area gets closer to you (increase in magnetic field). Now you shout 'turn it off' (electrical signal) and whether what you told responds to it or not is left up to the controller. But that strength in light/magnetic field, etc is picked up and converted into a signal, even the strength may alter what kind of signal it sends.

I searched for good explanations of how the relevant hall effect sensor/transducer/RPS's electronics works and found this online tutorial page: https://www.electronics-tutorials.ws...ll-effect.html . It looks pretty complicated, roughly guessing that this is university second year level electronics engineering or electronics.

This answers one of my three questions: The electrical current is located *inside* the hall effect sensor. Like a current is located inside a lightbulb, not outside it. To generate a specific output. In this case the output Hall voltage which you can find the formula in the light yellow box in between the two excellent diagrams of the hall effect sensor's workings.

[R2x1]

Surely it's obvious.
You're using a hall effect sensor in a laundry. It's a fish out of water.

[Kame]

Barry, since you like researching, learn how coil magnets work so you can understand the rotor, now the rotor spins using magnets which is a common technique for electrical motors. Since opposite polarities push away from each other and helps spinning.

Anyways, a hall effect sensor is not like a light. A light has no power until you switch it on, all sensors have constant power to keep them operational, a light doesn't. sensors normally have at least 3 wires, 2 for power /- and 3rd to act as a signal. A light only has 2 wires, /- where to make it live you need to use the switch.

A motion sensor light, has the sensor always powered and once it detects motion, it turns on a switch that powers the light. Well it acts like a switch, just like a hall effect sensor that detects magnetic fields.

You can research any type of sensor, they all work similar, just the trigger is different.