Hotpoint WMA35 – Killing motors

[Hollytree_Technical]

Hi All

I have just had another call about this machine but I am struggling to work out what is wrong.
The machine first suffered from a stuck motor brush which I removed, cleaned the holder (Bosch made motor) and fitted a new set after checking that everything else was okay, all was okay at time of test but I got recalled to the machine a couple of days later to find that the top brush holder (nearest tub) had melted and misaligned, at this point I assumed a fault in the motor winding as insulation and everything else was metering out as good and then bought a known good second hand motor, The machine has perfect motor control and the motor and brushes still felt cold after a rinse and 2 spin cycles back to back, but I have now had a call to say that it smells and sounds like it has done it again.
What would cause a motor to cook its brushes, I can only assume a control board fault but can’t work out what.

Thanks

Jem

[electrofix]

Re: Hotpoint WMA35 – Killing motors

the only thing on the control board that could have a bearing is relay failure but i cant think which one would do it. it like the armature is over currenting and their are only 2 ways that happens
1 faulty motor coils ( arm or field coil )
2 faulty timer shorting out field coil so armature only get supplied

interesting mystery but you may find its something else when you get there

Dave

[iadom]

Re: Hotpoint WMA35 – Killing motors

Was the second motor also a Bosch one, of the three types used on this machine they were the least reliable by a long way.

[Hollytree_Technical]

Re: Hotpoint WMA35 – Killing motors

Yes it was an identical unit, are the other makes completely interchangeable?

[iadom]

Re: Hotpoint WMA35 – Killing motors

Yes, the FHP and CESET motors are much better. The Bosch motors are notorious for taking out the pcb, something I can’t say I have encountered with the other motors TBH.

If ever I get a Bosch motor with brushes down on a WMA I always have a quick look at the pcb before changing the brushes.

[Hollytree_Technical]

Re: Hotpoint WMA35 – Killing motors

Well I had another look at this machine today, the motor meters out as practically perfect and the machine has full control of it over the wash cycle. There is no shorts or breaks in the wiring that I can find and the machine had a steady supply voltage of 238V and only drew a maximum of 11.4A in current.
After about 45 minutes into a 60c wash cycle the motor temperature reached approx 115C and the thermal trip cut out (the wash water was only 55C at the time).

It is my suspicion that there is something odd going on with the board control of the stator half tap but I cannot see anything wrong on the board so I will send it to EMW for test/repair.

The only other common denominator that I can come up with is that I put a new set of brushes into both motors, the first motor after it had jammed them in the holder and the second motor just before fitting.

I may well exchange the motor for a second hand FHP or CESET unit for the peace of mind even though it will have to be at my expense.

Jem

[Martin]

Re: Hotpoint WMA35 – Killing motors

Nothing to do with the drum being stiff affecting the torque strain on the motor then?

[Hollytree_Technical]

Re: Hotpoint WMA35 – Killing motors

The drum turns nicely as it has a pretty new set of bearings in it, certainty I can’t feel any obstruction by hand.

Jem

[Author]

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