Grinder not Happy

[Cane32]

Hi everyone.
Using my grinder cutting a wall tile when my BOSCH grinder model GWS 7-115 decided to play up and make a loud pop/bang inside the body of the appliance and stop.
Removing it from the extension lead and trying it again direct out of the socket with the RCD that i had used on the extension lead.
Switching it on again, it did it again.
Can you experts tell me if it is a broken wire in the lead ? or brushes on the motor or something major or something touching in side, it also tripped the consumer unit. I have a digital multi meter, is there a way i can test the appliance.. SWITCHED OFF.. to tell me whats wrong with it.

Your feed back would much appreciated. Cane.........

 

[bernardgreen]

I would help but my crystal ball is away at the cleaners.

Without a visual inspection and some dis-mantling it is impossible to diagnose the fault

 

[PrenticeBoyofDerry]

I would firstly look at the brushes!

 

[Taylortwocities]

Aye, brushes first.
The other point of failure tends to be where the lead enters the machine. After a while the flex conductors often fail at that point. That would not account for the bang though...

 

[DetlefSchmitz]

The last Bosch tool I had that went bang, was caused by the small PCB inside, where the mains cable connected, which had a high resistance terminal, and melted the board till there was a flash-over. I still bought another because the Multi-tool is one of the most useful tools I own.

 

[Spark123]

Have a good sniff of the unit, is there an acrid electrical burning smell with it?

Does it have a speed control on it or is it just on/off?

 

[Cane32]

Hi all ,
Thanks for the feed back , how do you know if the brushes have gone, and no it does not have a speed controller just on/off.
There is a small block which looks like resin with wires coming out of it after where it comes into the GRINDER with a little black on it but no melted wires.
Is there a way i can test the grinder with my multi meter to see if it the cable or the brushes have gone. What would cause the machine to go pop twice could it be shorting somewhere.

Advice needed, or look at a new one.

 

[Spark123]

Stick your multimeter set to low ohms range across the brushes, take the reading. Slowly turn the commutator reading the resistances, they should be the same all the way around.

 

[Cane32]

Set the meter to ohms 200 to 2000k all readings vertually the same 0.1 apart from 200 which read 3.6 is that good or bad measuring resistance is that correct. Cheers.

 

[ban-all-sheds]

all readings vertually the same 0.1 apart from 200 which read 3.6

That makes no sense whatsoever.

 

[mfarrow]

He means he set it at all scales and they all read 0.1 (surprisingly) apart from the 200 ohm range which read 3.6.

Was the 3.6 consistent throughout a revolution?

 

[Cane32]

3.6 CONSISTENT TROUGHOUT A REVOLUTION is that on the METER or turning the shaft in the winding.

 

[ban-all-sheds]

I don't know. Is it?