JohnLewis (Zanussi) Mystery! All Working But Won’t Complete Cycle

[benroper]

Hi folks! Puzzle time!

We’ve got a John Lewis JLWM1203 (Zanussi 914522514-00) machine here that i’m keen to keep alive. It has a mysterious issue…

Current state:
– Mains inlet valve has just been replaced and working perfectly
– Triac was replaced about 4 years ago, presumably not the problem
– Fully cleaned out (completely dismantled)
– Drainage pump is working well, no blockages, siphoning, obstructions, with healthy output
– Motor, brushes and belt all seem perfect
– Drum feels and sounds normal
– Water level sensor appears to be working (verified using diagnostic mode)
– Heater working perfectly (verified using diagnostic mode)

Issue:
Rinse/Drain/Spin programs all work perfectly, however the standard wash cycles (such as ‘Cotton 40 degrees’) all have the following problem:

– First half of the program is normal
– Machine appears to be failing to drain, such that when it tries to spin we get a bump, then it backs down. It tries several times then gives up. Just to reiterate: Draining is working perfectly under test and in the programs mentioned above
– When the program completes we get no error code, just the full program time displayed on the screen with no completion beeps
– Diagnostic mode does not report an error, all functions tested and working

Any suggestions much appreciated! Thanks!

[electrofix]

long shot
check heater for earth problems as it only seems to go wrong when it heats

Dave

[benroper]

Thanks Dave! Heater actually seems to be fine as programs run normally until draining time. We ran a 90 degree wash the other day that behaved the same way.

[electrofix]

small earth faults on heaters are a known problem on some machines. This does not stop the element from working, nor is it high enough to blow the house trip, but it is can be high enough to upset the electronics
you need to do an insulation test to earth on the heater, with thw wires disconnected, when its hot

Dave

[benroper]

Ok Dave I’m with you now – thank you. Will test and come back!

[benroper]

Thanks again for that Dave. Happy to report no issues with the heating element – Tested at 60 degrees and I’m seeing no earth leaking and a steady 30.0 resistance on my multimeter.

Any other ideas?

[electrofix]

if you are reading a steady 30 ohme resistance then you are not measuring correctly

you need heater wires disconnected, one meter wire on either of the heater connectione, the other wire on the earth wire on the heater and the meter set on a high ohm scale up to 2 million ohms

Dave

[benroper]

The steady 30 ohms is between the two element terminals. As I said I’m seeing no earth leak, i.e. I’ve got no reading whatsoever at any setting between a terminal and the earth pin… Unless I’ve got this backwards that means no leak, correct?

HOWEVER… I used diagnostic mode to heat the machine up to retest, but as it approached 60 degress it suddenly unlocked the door and made the ‘end of program’ three beeps. I’ve not seen it do that before. On to something?

[benroper]

Future reference: For anyone wanting to know how to test their heating element I used this video along with Dave’s instructions above: https://www.youtube.com/watch?v=Ftm8lDVVw2E

[benroper]

Still working on this problem.

– Ordered a new heating element
– Before that arrived the machine suddenly completed a few cycles as normal, but then went back to the same problem
– Replaced the heating element – no change

Any other ideas?

[benroper]

Still fighting the same problem. Today I replaced the main control board, but the problem remains. So far we’ve:

– Replaced inlet valves (as indicated by an error code)
– Replaced heating element
– Dismantled and cleaned out the whole machine
– Replaced main control board

What’s left? Replace the motor? Any other ideas?

[benroper]

I’ve just taken a good look around the motor and to the untrained eye there’s nothing obvious wrong with it, although one of the brushes is quite low, but not completely out.

I have three questions that I would really appreciate some opinions on…

A: While inspecting the motor I rotated it quite a few times and removed and reinstalled the existing brushes – Now running a wash cycle the motor is noticably louder when it’s turning over, making a loud mechanical whirring noise, where before it was much more subtle. Is this a clue?

B: How likely is it that some minor electrical component would fail, like the power conditioning unit?

C: Is it worth scrutinising things like the pressure sensor or output pump?

[benroper]

Wow this forum is dead! This is (hopefully) the final entry in my personal diary…

ORIGINAL PROBLEM (Refined version based on more testing)
The machine would attempt to accelerate the drum to high speed at the wrong moments in the cycle. The effect was a big bump, then the machine would back down (realising something was wrong), then just sit doing nothing. Occasionally it would start trying to wash again, but the program got very confused and often would finish with clothes still wet.

RED HERRINGS (These things made no difference)
– Replaced inlet valves (as indicated by an error code)
– Replaced heating element
– Replaced main control board

SOLUTION
Replaced the motor. I suspect the dynamo (that senses motor speed) was probably the issue, because the motor itself was still working fine. Unfortunately this looked to be a sealed unit, so I have replaced the whole motor (£110 from RansomSpares) and now the machine is working like new.

Hope that helps someone, someday!

[Author]

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