Miele intermittent failure

[aardvaarkk]

Hi, my Miele W524 stopped during a wash with rinse light flashing. We tried to run the drain and spin, but it refused twice – ran the pump and turned the drum a bit, then stopped with the same error indication. Third time it went ok, but now I’m worried. Not really sure where to start – what could it be complaining about?
​​​​​​(A few days ago I had some trouble with the door not unlocking, could these be connected events?)
thank you.

UPDATE: SOLVED!
Summary: the tacho coil had gone open circuit. Thus the machine didn’t know that motor was turning, so refused to operate (presumably in case it was jammed and overheating.) Also, not knowing that the motor wasn’t turning it also refused to open the door for safety. I replaced the motor control unit, and it now just works.

[electrofix]

think the rinse light may be a motor fault

check the carbon brushes

Dave

[aardvaarkk]

Thanks Dave!
I’m curious to understand how the brushes could be at fault — the drum turns both ways, and spins at high speed, so it seems that juice is getting to the motor… any thoughts?

[electrofix]

they may be about to fail and sparking causing motor speeds to be incorrect

Dave

[aardvaarkk]

Thanks — I will try to check out the brushes.

[electrofix]

to get brushes back

push them into the holders till they lock
replace the cover then find some stiff wire ( i use a ver small allen key) insert down the top of the brush holder and push till you hear it click

do either of the brushes look dull on the face or are they both shiny

Dave

[aardvaarkk]

Thanks for the tip for getting them back in. Both are fairly shiny.

[electrofix]

then its not the brushes then

does the motor run at all when you try it ?

Dave

[aardvaarkk]

The motor turns at its slow speed. ( I thought it went both ways, but not so sure now.)

And I did get it to run the drain/spin programme once, so high speed spin worked for a time (though it seems it won’t do it now because controller won’t even try.) I can’t get it to try high speed now.

For clarity, here’s what it was doing:
1. select drain/spin, press start
2. motor spins one way briefly (balancing load, I guess?)
3. error lights start flashing
4. motor again briefly (balancing load, I guess?)
5. stops.

It also seems that the door interlock is preventing electronic door opening (even if I turn off and on again.)
So perhaps it thinks the drum is spinning?
Or it thinks there’s water in the drum? (I will try to test that again when the brushes are back in, and see if it tries to pump it out.)
As a non-expert I feel this is the vital clue…?

thanks again very much for your help, Dave. Much appreciated.

[electrofix]

when you say motor spins breifly how briefly and how quick ?

before you close the dront again
1 check the magnet is still intact on the nd of the armature
2 tell me when you have done it as we need to check the motor circuits are intact by using a multi meter

Dave

[aardvaarkk]

Briefly just one or two seconds, at slow speed
(as I recall, in the drain/spin programme the machine does quite a bit of shuffling the clothes around before it tries to run at full speed. This is failing long, long before it gets to that point, still in the draining and shuffling stage, after less than 10 seconds or so.)

I’ll check the magnet later today. What am I looking for?

[electrofix]

if its broken it will be obvious. the magnet spins inside a coil housed in the brush assembly. its a small generator. the feeds a voltage to the board. If the manet or the coil fails the board wont know what speed the motor is doing and will stop the machine with a fault code. both the magnet and coil need to be checked

Dave

[aardvaarkk]

Thanks Dave — that makes a lot of sense.
I put the previous photo here, so there’s a lot more resolution. The outer ring of the tachometer is visible — and looks unbroken.
https://www.dropbox.com/s/fqm87icf39…ushes.jpg?dl=0
(The machine is currently reassembled because I wanted to try some more experiments. After experiments, I’ll take it apart again!)

[aardvaarkk]

Ok, experiments done. Even on wash cycle, as soon as the motor turns on, the errors appear. It makes sense that the problems are in the speed detection.
The magnet you mentioned is indeed on the motor, and looks ok:
https://www.dropbox.com/s/2rmf4l2aaqxu2c1/IMG_20210225_175032610.jpg?dl=0

Ready to test with a multimeter – what should I test?

Many thanks

[electrofix]

test that coil (tacho) in the brush assembly. was wondering if its gone open circuit

Dave

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