Bosch 9" Grinder

[GSRocket]

Hi guys, Probably not quite the right forum but somebody here will probably know.
I have had a GWS 22-230 LV Bosch grinder for about 6 or 7 years now but has suddenly stopped.
The cable was tested and is good. The twin points in the switch were slightly pitted but now polished smooth.
And there is plenty of life still in the brushes.
So what should I look at next? It hasn't done a huge amount of work.

[eskimo]

you obviously are not a sparky, else you know how to check it out.

Having said that, how have proved the lead?
Are you checking for continuity?, and with what?
If you are getting continuity from Active pin of plug thru switch and to windings of motor and including Neutral continuity from motor backwards towards N pin of plug then its in the motor ?
get a sparky to check it out

[GSRocket]

Absolutely no sparky, or I wouldn't ask the question.
The lead has been checked by a fire tech, or also checked the switch with his gadget and said it was good.
He doesn't know about motors 'tho.

[Combustor]

Not sure aboutyour particular Bosch, but many power tools now have an auto disconnect device when brushes wear to their lower limit. Look to see that the brushes are still firmly in contact with commutator amd have not been released. Some brushes include the release in the brush itself. When worn to minimum length a tiny insulated sprung plunger is exposed which pushes the brush out of contact. You should not be able to push the brush any further into contact with the commutator.
Otherwise, get someone familiar with multimeters to do some simple continuity checks and know for sure where your problem is. Regards,
Combustor.

[jhovel]

You could have a look for suppressors in the handle. There are usually at least one capacitor and possibly 2 small chokes. If one of the chokes is gone open circuit, it would leave the motor 'dead'. Follow Eskimo's advice though - if you don't know what I just wrote, don't go any further on your own.
It could be a break in the stator coils, in which case you are possibly up for a new grinder, sadly....

[GSRocket]

Ok, narrowed the problem down. It is in the switch. Continuity testing kept showing everything was okay,
but we decided to plug the lead and switch (which was locked on with a zip tie) into 240 and checked the voltage after the switch and we were getting very random and inconsistent low readings. But there was also a very quite and intermittent buzzing
sound from the switch.
When I opened up the switch there were small burn marks on the double points.
So it would seem the points do not positively contact each other.

[GSRocket]

Well.... the problem was too simple.
It was the 3 pin plug. Finally dawned on me to test the cord with 240 (without the switch) and the best
we could get was 180v. The plug is very light for what is otherwise a sturdy powerful machine. The earth prong
broke off 2 months after I bought it.
Anyway, replaced the cord with four metres of an extension cord that I seriously injured just the other day.
It goes good now.
I guess it's a good thing it won't run on 180v.