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From: N_Cook <diverse@tcp.co.uk>
Newsgroups: sci.electronics.repair,uk.d-i-y
Subject: Re: Failed water pump and sump query
Date: Mon, 03 Feb 2025 19:01:46 +0000
Organization: A noiseless patient Spider
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On 03/02/2025 17:45, Liz Tuddenham wrote:
> N_Cook <diverse@tcp.co.uk> wrote:
>
>> Only made a preliminary check o this 1KW pump and float switch in a
>> sump, prior to dismantling ad exploring further.
>> Sump full of water but no pump action. Moving the float about made no
>> differece. Tapping the pump casing made the pump work until the float
>> switch dropped to the cut off point.
>> Refilling the sump and again no pump action until tapping the casing and
>> again stopping properly. I cannot see what in the way of sticky motor
>> brush or loose/corroded contact inside the motor housing could produce
>> this symptom.
>
> You haven't said what sort of motor it is, but if it is a commutator
> motor with brushgear, the fault could be worn-down brushes to the point
> where one of them is almost-but-not-quite touching the commutator.
> Tapping the motor gives some sort of contact and then the vibration of
> the motor allows it to touch the commutator often enough to keep it
> running.  This will give a fireworks display around the commutator and
> will do considerable damage if it continues.
>
> If it is not a brush motor, a similar thing can happen if the terminals
> have become loose.  The sudden shock torque as the motor starts is
> enough to make contact and vibration will keep it running; then the
> contact is lost again after the motor has stopped.
>
> The first things you need to check are what type of motor it is and
> whether the supply is reaching the terminals in the connection box on
> the motor casing.
>

The pump is a JTFS Mini Micro domestic sewage pumping station,
probably JTFS190NN
No type technical details found but no obvious external  starter cap 
outside the motor casing or casig bulge.
The other consideration is it was installed 10 years ago, tested working 
then, but never heard to be working since.
It should have worked in a flood situation last year but it did not 
(automatically of its own accord that is) , no maintainece or testing or 
inspection in those 10 years by the owner or anyone else.


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