Functional Test of Brush Motor

[Simmy]

I am trying to fix up a Blomberg 230 (about 10 years old) and I have managed to fix some problems but now I am stuck with the motor not working. I have ohm tested it and I get 2-3 on both the brushes and the commutator. I know that this motor can be tested, (with great care and only for a moment) with live current. I have tried to test with power but with no luck, I think I may not be connecting the test wires properly. Any advice on how to connect the test wires would be greatly appreciated.

Also the motor might be shot (I think knackered is the term in the UK), there is black soot on the end opposite the brushes of the commutator .

Any help advice greatly appreciated!
Simmy

[Martin]

Re: Functional Test of Brush Motor

Simmy wrote:Also the motor might be shot (I think knackered is the term in the UK), there is black soot on the end opposite the brushes of the commutator .

Simmy,

No ‘live wire’ testing please, it is not necessary. The black soot is probably just black rubber ‘dust’ from the drive belt after all. 🙄

Do look closely at the state of the brushes (should be 2 cms long and the tip shiny and smooth) Clean up the commutator, refit brushes and test across the brushes (should be 4 to 6 ohms usually)

Check motor connector plugs and its terminals carefully also, then plug in and run test 😉

What aspect of our trade do you specialise in by they way?

[Simmy]

Re: Functional Test of Brush Motor

Do look closely at the state of the brushes (should be 2 cms long and the tip shiny and smooth) Clean up the commutator, refit brushes and test across the brushes (should be 4 to 6 ohms usually)

The brushes are less than 1 cm, and 3.8 ohms between them. The tip is partially shiny and looks scratched. I assume this means I should change them?

What aspect of our trade do you specialise in by they way?

Refurbishing and selling old machines that people are getting rid of because its not worth it for them to fix.

Thanks for the help!

[Martin]

Re: Functional Test of Brush Motor

Changing the brushes might be advisable whilst refurbishing it although I guess it’s not the cause of the fault.

Have you got readings through the windings etc? The armature reading of 3.8 ohms is passable for sure I reckon!

[Simmy]

Re: Functional Test of Brush Motor

Have you got readings through the windings etc?

Yes, 2.1 Ohms on the windings.

For the refurbishing is there anything to do besides getting rid of the rubber dust. Should I clean the contacts on commutator? If so using what?

Thanks for all the help!

[iadom]

Re: Functional Test of Brush Motor

Simmy wrote:. Should I clean the contacts on commutator? If so using what?

You should use something called a comm stick. Usually available from main spares wholesalers, also model shops sell comm sticks for use in radio controlled cars etc.

[bobokines]

Re: Functional Test of Brush Motor

Personally I am against cleaning the commutator. The patina on the commutator is much harder and smoother than clean copper and reduces brush wear dramatically.

I have done extensive research on brush wear (in an earlier life when I worked as a design engineer in an electric motor company). Research has proved that the commutator should never be touched with a com stick or emery paper unless it has been physically damaged by brushes wearing down to the tamping (this is the bit the pigtail is bonded into).

If the brushes are changed before they start to arc then leave the commutator alone…

Bob

[Martin]

Re: Functional Test of Brush Motor

Simmy,

With respect to my learned colleagues, from what you have reported so far I reckon your motor is OK :tup:

Your problem is more likely the supply from the module?

Blomberg is a specialist subject best left to our Antarctic friend…so at this point I pass the baton to him…………..

[leavemetogetonwithit]

Re: Functional Test of Brush Motor

Simmy, may I ask how long you have been in this trade? Something about what you’ve written makes it sound like you’re quite new to it. You might find a repair manual like the Haynes one very useful, if so. 😉
Mike.

[Simmy]

Re: Functional Test of Brush Motor

First, thanks to everyone for the excellent advice!

Your problem is more likely the supply from the module?

I have been meaning to check this… (I assume you mean that electrical power is being supplied? My UK english isn’t 100{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} mine’s US)

how long you have been in this trade?

As you guessed I am just starting out I have taken a couple of courses on the subject and have the books from them. Unfortunately the books don’t always cover everything and I don’t remember some of the things that aren’t included.

You might find a repair manual like the Haynes one very useful

Where can I find one?

I have found a site where the guy sells his own generic manual http://members.lycos.co.uk/primelisting/motors.html which I was considering buying, any thoughts.

Thanks for all the help!

[Simmy]

Re: Functional Test of Brush Motor

Quote:
Your problem is more likely the supply from the module?
I have been meaning to check this…

I just checked if power was going to the motor via the connector and on spin its around 60V.

[leavemetogetonwithit]

Re: Functional Test of Brush Motor

Simmy wrote:

You might find a repair manual like the Haynes one very useful

Where can I find one?
Amazon I should think http://www.amazon.co.uk

Simmy wrote:I have found a site where the guy sells his own generic manual http://members.lycos.co.uk/primelisting/motors.html which I was considering buying, any thoughts.

Had a very quick look at the site. The line drawings featured look pretty naff (er, slang for not very good). Think the Haynes is better and probably cheaper too.
Mike.

[Dave_Conway]

Re: Functional Test of Brush Motor

Simmy, drop me an email please, I’ll try and get a Haynes washer manual to you, are you still in Israel or am I confusing you with someone else (it’s late ;)) ?

Dave.

[Simmy]

Re: Functional Test of Brush Motor

I have got it working, there were a couple of bad contacts on the timer circuit board, which I fixed.

Now here’s my next question: Does the amount of wear to the carbon brushes affect the motors ability to turn the drum? I ask because during testing of the machine when I put it on the spin cycle empty it goes fine, but when there is a load inside, any time it is trying to turn the drum, it usually sounds like the motor is spinning but the drum isn’t moving. Or it moves only a little bit. Could this be connected to the belt? The belt looks fine and seems to be sitting just fine. Also when I took out part of the load it was able to spin without a problem.

Thanks for the help!
simmy

[Martin]

Re: Functional Test of Brush Motor

Simmy wrote:I have got it working, there were a couple of bad contacts on the timer circuit board, which I fixed.

I guess your machine has a Timer/Module board fitted then rather than a seperate motor control module? If that is the case then that Timer/module may well have an ‘out of balance’ detection system causing this fault or further bad contacts to it need checking out maybe?

[Author]

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