[DaveO44]

Re: Bosch WFT2800GB /13 no fast spin after brush change

Martin,
I have now fixed the motor – your information that there was a separate winding for the fast spin led me in the right direction.

In fact the stator was installed the wrong way around, but by inspection and checking with the multimeter, I was able to reassure myself that there was unlikely to have been any damage.

With the stator the wrong way around there was no field winding resistance to see between pins 1 and 2 and the only field winding resistance came up as 1.2 ohms between pins 2 and 3.
With the stator the correct way, between pins 1 and 2 there is 1.6 ohms and between pins 2 and 3 it is 3 ohms.
The armature is connected between pins 4 and 5 and gives around 3 ohms either way, while there is apparently a semi conductor device between pins 6 and 7. I was told that the vibration sensor is within the motor by an ex Bosch technician, so it might be that.

Many thanks for your help – hope my result will aid some other unfortunate who forgets to mark the pieces before dismantling. I guess the photo I saw on the web, indicates that the construction of these motors is not robotised and the laminated iron core section can be selected either way around for fitting with the field coils.
Cheers David

[DaveO44]

Re: Bosch WFT2800GB /13 no fast spin after brush change

Thanks Martin and Andy,
The w/m is being used at the moment when we have lot of washing, which is then transferred to our spare machine for a spin, then back for a dry if necessary, so it has been tried empty and with normal loads.
I have some fine emery paper and switch cleaner, so will give the commutator a spin with some paper around it to clean it up and then clear out the segment gaps if not designed to be flush. I will also see if I can spot any open circuits on the field and armature windings, keeping in mind that there might be a reversal with the connections. Perhaps I can deduce if a reversal is in fact the cause.
Cheers David

[DaveO44]

Re: Bosch WFT2800GB /13 no fast spin after brush change

Thanks Martin.
There is an outside chance that the stator was connected the wrong way around to the main body of the motor. I am very methodical when disassembling, but did not mark the parts beforehand, however I compared against a photo of the same motor offered as a spare and my reassembly checked out with the photo.
I have been reluctant to reverse the stator end in case that would damage the motor or control circuitry.
The invoice from Uk Whitegoods shows the part number to be 496876.
There was no complaint about high speed spinning before the motor gave up the ghost and failed to spin at all. Also both stators with the new brushes present the same problem e.g. working fine at all normal speeds, but failing to get the correct revs during the spin cycles, though trying.
I must admit I have a reluctance to purchase a new motor and then find the fault is part of the control unit. By that time it might have been worth replacing the whole washing machine instead.
Would the motor work at all if the stator was reversed?
Tks

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