Contacts worn out on V8? 22v on end of extension and brush spins when connected

[lollol]

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Hi all
If anyone can help I would be very grateful, I have done the following...

Dehaired the brush
Then dismantled the brush head, cleaned (took all plastic parts apart and took the motor unit out)
Removed leads from motor and tested the cables continuity from connection at the extension tube to disconnected wire ends in motor housing
Reassembled
Then tested voltage at end of extension tube with motor running (it was around 22v)
Then connected head to a bench power supply (22v) and the motor spins fine
Tested the articulating connected at different angles and the motor still runs OK while connected to bench power supply
Connected the head to the extension tube motor does not turn or even briefly attempt to turn even whilst operating the unit and wiggling the connection

I therefore assume that the male/female connectors are at fault. Is this a reasonable assumption and if so are they serviceable, what is the best way to fix? I can only think of trying to slightly tighten by crimping the female connectors if I was able to get access to them or stuffing some aluminium foil in the female connector to bridge a possible gap.

What do you think?

Thanks

Lawrence

[lollol]

when i remove the extension tube I still measure 22v at the terminals on the main unit where the long tube connects but if I connect the brush head here nothing happens.

I have cleaned all contacts with IPA.

I can turn the head by hand, it rotates relatively freely with small vibrations as it returns, is this normal? when I connect 20v to it, it whizzes happily and draws 1.2amps.

what can the problem be?

[MVacs]

It would seem the main unit is outputting enough voltage to get a reading but not enough juice to run the head?

Have you a friend or relative with a V7, V8, V10, V11 or V15? If so, try another head on there.

If still nothing, you may need a motor unit.

[lollol]

mmm thanks. if I could measure the voltage with the head connected and switched on I guess I could see the voltage drop out, might be hard wiring it that way.

would it be a head or PCB problem if the voltage is cutting out under load.

I don't even feel a pulse from the head when switched on... I am also measuring 1v from the contacts when its switched off, is that normal?

[MVacs]

would it be a head or PCB problem if the voltage is cutting out under load.

The head would be more usual. But an internal component in the motor unit can be as well. That's why it's better to try an alternative head if you can.

[lollol]

I found a friend with a V11 , he broke the plastics that connect the head to the tube so I was going to use it to test my unit, he then he said I could have it so I thought I could perhaps salvage 1 head from 2 heads, great I thought. He got back to me today and said his wife had thrown the head out which is a shame.

He has taken my v8 main unit and head home and tried it with the head from his v11, it doesnt work, are they compatible? would it be safe to assume that its a fault with my unit/pcb?

Tested my head again on the bench, working perfectly from a bench power supply. Only thing I note that there is a high (>3A) startup current.

[lollol]

bad picture of voltage at leads in side the head unit...

[lollol]

dont know if you can see the blur but head is spinning, drawing 0.7a or there abouts

[lollol]

PS. if its a PCB problem is there anything obvious to look for once I have dismantled the main unit?

[MVacs]

He has taken my v8 main unit and head home and tried it with the head from his v11, it doesnt work, are they compatible? would it be safe to assume that its a fault with my unit/pcb?

I would say so. They do go faulty. Yes, they're compatible.

I can't advise on internal repairs on them, as we only ever change full motor bodies.