Miele WT945 washer/dryer, 'rinses' light flash, no drum spin, EL140A....

[AlastairE]

Ive just got hold of a replacement machine for the 4 year Beko that self-destructed, flooding the kitchen--Drum-Spider strikes again!....

This replacement is an old machine, but excellent condition, and infinitely better built than that plastic and crap Beko. Only trouble is--It lasted approx 3 wash cycles before troubles....Just my luck!

Actual fault presented, the drum would just twitch or move just a little when it was supposed to run. This would happen in both directions, and if the drum failed to run three times in a row--the Rinses light flashes and machine pumps out, sounds its end of cycle/alarm.

Much research and contact with a repairer in Netherlands suggests that the EL140A Controller board has issues, notably the small Mains Transformer (Which he has had to have re-made by another manufacturer and sells under his own brand-name, 'youfixit' the originals are no longer available)-- and the motor control relays, (Power and reverser relays) are the usual causes of the above fault, and are mounted on this controller board.

I ordered some replacement Relays,--two different types, and the Transformer from the guy in Netherlands, --guess which arrived first! Still waiting for the relays, and will update when I get them.

Motor and its brushgear/com is in excellent condition, look hardly worn, just a small amount of black dust on the holders, removed checked, all cleaned off and refitted. I had at first thought a brush was faulty/worn or stuck in its guide as the machine hadn't been used in some years.

 

[RichardMNZ]

I have ordered a transformer off the guy in the Netherlands. Worked wonders on my W360.

When my transformer went it was completely dead.

Did you check the brush holder. I had an issue with my w360 where corrosion on the spade connector to the brush caused an issue.

 

[RichardMNZ]

If it turns out to be relays and fuse then perhaps some new shocks will be needed too?

 

[AlastairE]

Shocks is something I'll check when I pull the thing apart (Again!)--probably later today. I now have the relays for it as well....

 

[AlastairE]

Well--I fitted the Transformer and the two relays to the controller.

Loaded it up and all was well--Until it got to the rinses cycles. With this machine it takes in a lot more water on these stages than on the washing phase.--so much so, its approx 1cm above the lower lip of the door-seal.

Managed to get it through this then onto spin and drying--which ran fine in both cases.

It seems, during this High load/low speed rinses stage (High motor current/comparatively low motor voltage) condition causes the fault.

The Motor is controlled by an IGBT rather than a Triac--principle is the same more or less, so tha'ts the next part to try. Failing that--I'll rip the motor out and really examine closely
--I doubt its a fault in the actual IGBT Driver circuitry as the Gate Impedance of the IGBT doesn't vary appreciably with the load it sees.......

Anyone got a Growler...!

 

[RichardMNZ]

I have read that with the el150 boards there have been issues with the IGBT.
Please let me/us know how you get on.

 

[AlastairE]

Ah--Thats good to know. I think the 150 is very similar to the 140A, and as soon as I get the new IGBT (coming from Germany) I'll let you know....

The guy in Netherlands recons the IGBT is either good or not, no inbetween, but IME Ive had intermittent IGBT's in plasma TV sets etc--Not often, but does happen....

 

[RichardMNZ]

With the el150 it also paid to replace the LM315.
I don't know if the el140 has an LM315 but that's what others have done too.

 

[AlastairE]

LM315.....

Thats an oddball, Sure its not a LM317...?

 

[RichardMNZ]

Yes, sorry. It is Lm317. 8 pins

Memory is not what it should be

 

[AlastairE]

A little progress....

The IGBT didnt arrive till after the weekend. So on Saturday, I checked my stock of stuff (For Flat-Screen/Plasma TV sets) and found a suitably rated IGBT.
Original is a 20A 600V (13N60) device and I had a 40A 630V device. (63F4A) Shoved that in.

No different at all, still same fault.

I examined the circuit, and drew part that has the relays and IGBT--all the motor 'power' side of the board. I noticed a resistor in the Emitter of the IGBT, a Very Low resistance resistor of 0.047 ohms, a 3W ceramic cased wirewound part.

This is there so the controller can assess the actual current (and therefore the Load) on the motor, I assume. I suspected, that If this resistor had increased somewhat in value the effect would be premature over-current sense, and indicate fault condition, (Rinses light flashing).
--I didnt have such an odd value but did have some similar near 'short-circuit' resistors and was able to make up by series/parallel of three a value of 0.039 ohm.

I installed this and the machine worked. It did indicate the fault once on a rinse cycle when fully loaded with washing, but got through it without intervention.

I'm suspecting the Motor may have an issue, and managed to find a suitable replacement cheap. Ive got some replacement shock-absorbers coming for good measure too. Will post when I know more....

So far, I'm quite impressed by the thought of design and the robust construction of this machine. Built like a German Battleship! I firmly believe once its sorted, it'll outlast any new cheaper make washer--even though its got a few years on it already!

 

[AlastairE]

Got hold of the replacement S/H motor. For good measure--I stripped and cleaned it, added a tiny bit of oil to its bearings through a hypodermic and cleaned the com and its undercuts.

Reassembled with new brushes--although it didn't actually need them, I had got some anyway.

I tested the motor on 12V DC from a sealed lead-acid, wiring the fields in series with the armature. It ran nicely. I also was able to slow it to nearly stopped by hand to check for any dead-spots etc, there were none and just a completely even turning power.

Changed it over with the original in the machine, fitted some new shocks at the same time and the machine ran normally.

Ive since examined the original motor. I see no faults with it. The com is clean and has very little if any wear--certainly less than the replacement. The Only thing I can find is one brush is worn down a bit more than the other, and the rear bearing is just slightly noisy.

--I did see something--somewhere-- saying that unequal brush wear indicates a fault with the motor.....

I ran this one in the same way as the other from 12V, this time I noticed a cogging effect or pulsing effect as the thing turned, in time with each of the com segments, but otherwise no different....

DC resistance checks were same as the replacement motor. TBH--I don't think this old motor is actually faulty....

We'll see how it runs for a while....

 

[AlastairE]

Ive now dismantled the brush-frame of the old motor--again.

In there there's two small 0.01uF 275V X Rated capacitors. One is completely open circuit, other tests fine......

Its the cap thats connected to the shorter of the two brushes, from there to the frame of the motor.....
--Interference suppression I guess.....

Hmm-- Clue at last!

Only thing I can think of in light of this discovery--Maybe the motor is sending back to the controller pulses/spikes from the arcing brushes and the controller saying--Sod This, and shuts down, giving the error indication.

What I Should do--In the interests of science would be to build this motor back up with new caps and brushes, and bung it back in....
--With the current batch of sciatica I have,--I cant see THAT happening soon!

 

[Henry V111]

Hello AlastairE, I appreciate that this is an old thread, however if by any chance you happen to review it could you please let me know what it was that you eventually found that was the cause of the original problem with your WT945. I am experiencing exactly the same problem, everything works except the wash program.
Best regard

John