Vacuum Cleaner Problem

[skyhawk20]

Hi Guys

Can someone out there put me straight please, the rotating brush on the vacuum cleaner keeps stopping.

First off, it’s a vacuum which runs off rechargeable batteries and what happens is when its switched on a small green indicator light comes on and the brush rotates for about 2 to 3 minutes then stops rotating, the indicator light also goes off.
If I switch it off and leave it for about 3 minutes and then turn it back on, it keeps doing the same thing runs then stops.


I’ve stripped it down and managed to get my meter probes onto the two connector wires as shown in my photo and got a reading of about 12 volts, the brush rotating and green indicator light being on.

When the brush stopped and the indicator light went off, I was still getting a voltage reading at the wires which went up to about 14v.

Can someone correct me if I’ve got this wrong, am I right in assuming the fault is on the small circuit board which the indicator light is on or would it be the circuit board on the motor itself.

Have a look at the photos and hopefully someone can tell me if I can rule the motor circuit board out or tell me how I can test the motor board?
Also on the motor photo what are the two coils I’ve marked with an X and what are they for?

My thanks for any advice

Skyhawk

 

[Ylli]

How low does the voltage drop just before it shots off?

The inductors on the motor are for reduction of electrical noise.

 

[skyhawk20]

Hi Ylli

Thank you for your reply, without the brush roller attached in other words just the motor which drives it, the run voltage is 13.15v and as near as I can tell it drops to 12.97v so not a big drop in voltage.

It still cuts out even with the brush roller removed so its not the drag caused by the roller itself, where do I go from here?

 

[duke37]

If the voltage rises when the motor stopps. then there is a break in the circuit. Possibly worn out motor brushes.
The motor probably has brushes since it is fitted with the interference suppresion chokes.

Nice photos!

 

[pharaon]

If the voltage rises when the motor stopps. then there is a break in the circuit. Possibly worn out motor brushes.
The motor probably has brushes since it is fitted with the interference suppresion chokes.

Nice photos!

i agree with duke37, the issue is in the motor itself not in the circuit ,,
so to make sure try to run it while the motor is out as in picture and when it stop try to manually rotate the motor with your hand, if it start rotating then the motor is the issue or something prevent it from rotating properly

 

[skyhawk20]

Duke37 and Pharaon

Thank you both for your replies, I must admit I thought it was something wrong with one of the circuits especially as the green light was going out.

Can I ask you both why you thought it was the motor and not the circuits, I'm always ready to learn the reasoning behind someones answer?

OK back to the problem, I took the drivebelt off so all the motor had to do was drive itself and your both right it just kept running no problem at all, in fact I nearly burnt my finger trying to stop the pinion rotating, but as soon as I put the belt back on the problem was back, so I realised it was something to do with the toothed gear it was driving.

It did seem a little stiff to turn so I gave it a squirt with WD40 and its now appears to be running ok, although
I haven't assembled it back together with the brush yet , but I'm wondering how long it will run for before I have the same problem again.
I'm sure if I tried to buy the motor assembly I'll be told its a non serviceable item or its not sold as a spare part.
I'm just wondering what would be best to lubricate the gear pulley with so it doesn't run dry too quickly, any ideas?

 

[pharaon]

Can I ask you both why you thought it was the motor and not the circuits, I'm always ready to learn the reasoning behind someones answer?

almost no component that can go bad easily, and as long the motor do rotate then the component are fine cause if it were dead the motor may not start properly,
WD40 is fine although i don't this that would be the reason for the motor to stop, i think it's what that black thing moving is what kept the motor from rotate

 

[duke37]

The reason I went for motor trouble was the voltage at the motor was higher when it was not working indicating no current going into the motor. This reasoning is at conflict with the mechanical theory.
Disconnect the motor and measure the resistance across its terminals with an analog meter. Turn the motor slowly by hand and see if the resistance is consistent. I do not see how you can visually check the brushes.

For lubrication, I would go for car engine oil.

 

[skyhawk20]

Hi Pharaon and duke37

Thank you both for explaining why you suggested the motor was the cause of the problem.

duke37, I agree there does not appear any way to get into the brushes anyway as Iv'e mentioned above I did find the gear wheel seemed to be sticking so Iv'e given it a squirt of WD40 and put it all back together for now to see how goes in use.

I may well find I have to strip it down again if the issue comes back, so I'll ask now, Duke you said measure the resistance across the motor terminals, would I need to desolder the wires from the small circuit board where Iv'e shown below in order to do the test??
If not I'd appreciate it if you could show me by indicating on one of the photos I've already posted.

Am I right in assuming the resistance should be consistant??? ie when gear is stationary or turned by hand.

You also mentioned analog meter, would a digital meter serve the same purpose??

Thanks again for your time

Skyhawk

 

[duke37]

You only need to unsolder one lead.
The reading will vary a bit and a digital meter may give rapidly changing digits which cannot be interpreted. If the armature has partially burnt out, then there will be open circuit at one position.
When turning the motor, put a sideways force on the pulley, similar to what the belt does, to see if a bearing is faulty.

The atached circuitry may be to protect for an overload and may reset when cooled down.

 

[skyhawk20]

Duke

Thanks for the lowdown on the soldering and what type of meter to use.
The whole thing is back together for now so I'll see how it goes, its not the main vacuum so it only gets used infrequently, but Iv'e made a note of what youv'e said.

Its much appreciated

Skyhawk