Bosch gws 600 repair (115mm angle grinder)

[6ply]

I have two of these 115mm grinders, both bought around 2014, and one of them suddenly stopped working during use. It stopped dead without playing up beforehand. Before I consign it to the bin, I would like to confirm there is no easy fix.

The gearbox is good and the fault appears to be electrical. The fuse and switch are tested good. The brushes look used but not worn out. However, I don't know what the original brush length would have been. There is what looks to be a mains filter fitted which I have not yet tested.

Any suggestions on what the likely fault could be or recommendations for further testing?

 

[6ply]

Tested the filter for a short. Not shorted.

 

[Kram]

Have you checked the cable for breaks and that the wires havent pulled out of the plug terminals? That has happened to me before

 

[Agroshield]

Trace the wires through from the plug to the brushes and field coil. Temporarily connect directly to the wires as near as possible to the motor. That eliminates the switch, the suppressor (CBB668A), the soft start and any break in the cable.

If it still does not go, the only economic thing is to try new brushes (or the brushes out of your other one), but after that, it becomes too costly to repair.

Parts diagram (maybe) here:

GWS 600 - 0 601 375 0X2 | Product Detail Page | Power Tools | After Sales Service

GWS 600 0 601 375 0X2 220 V Universal Angle Grinder Bosch BL Bosch blue Professional

www.boschtoolservice.com

Use the equivalent of the 0 601 375 0X2 number to find your own. Wiring schematic lower left.

 

[Mikes]

In the 2nd photo, the brush looks to be well down in its holder so is probably very worn. I'd buy a couple of brushes and try that. I've had them stop before when the little wire to the brush has fractured.

 

[Pete.]

9 put of every 10 grinders I have repaired it's the wire broken inside the rubber sheath just at the back of the grinder. It looks perfect but if you grab the copper end of the wire with pliers and pull you find the conductor is broken inside and it just stretches until the rubber breaks.

It's the very first thing I check on all electrical hand tools of they don't start.

 

[6ply]

Lots of good suggestions, guys.

Have you checked the cable for breaks and that the wires havent pulled out of the plug terminals? That has happened to me before

Yes, @Kram the cable and plug are good. Continuity tests show there are no breaks.

Trace the wires through from the plug to the brushes and field coil. Temporarily connect directly to the wires as near as possible to the motor. That eliminates the switch, the suppressor (CBB668A), the soft start and any break in the cable.

If it still does not go, the only economic thing is to try new brushes (or the brushes out of your other one), but after that, it becomes too costly to repair.

Parts diagram (maybe) here:

GWS 600 - 0 601 375 0X2 | Product Detail Page | Power Tools | After Sales Service

GWS 600 0 601 375 0X2 220 V Universal Angle Grinder Bosch BL Bosch blue Professional

www.boschtoolservice.com

Use the equivalent of the 0 601 375 0X2 number to find your own. Wiring schematic lower left.

@Agroshield thanks for the link and suggestions. The parts diagram and schematic looks useful.

In the 2nd photo, the brush looks to be well down in its holder so is probably very worn. I'd buy a couple of brushes and try that. I've had them stop before when the little wire to the brush has fractured.

@Mikes and @Agroshield I'm tempted just to skip ahead and replace the brushes before trying anything else. Originally, I thought the brushes looked "worn but ok", but now I'm wondering whether they are down to their limit. There is an eBay advert for OEM replacement brushes that suggests they could stop suddenly, which is exactly what happened to me.

9 put of every 10 grinders I have repaired it's the wire broken inside the rubber sheath just at the back of the grinder. It looks perfect but if you grab the copper end of the wire with pliers and pull you find the conductor is broken inside and it just stretches until the rubber breaks.

It's the very first thing I check on all electrical hand tools of they don't start.

Thanks @Pete. but a cable break has now been ruled out.

 

[Turbo]

Sometimes with brushes the spring pushing them in fouls on the brush holder when the brushes get worn. It is no longer pushing the brush in. As a temporary fix put something between the spring and the brush and see if it works.

 

[6ply]

I've ordered a pair of replacement brushes. If nothing else, I'll have a spare for the other grinder.

 

[indykid]

The autostop function you mention above is a sprung pin embedded in them that pops out and breaks the contact with the commutator to stop the brush running down to nothing. If you take the brushes out and see a dot on one of them, they're worn out.

Work throw away loads of grinders that have just worn the brushes down to the pin (bosch, metabo and dewalt) but they're all 110V so no use to me. I still have them apart for a look before they go back in the WEEE bin.....

 

[6ply]

The autostop function you mention above is a sprung pin embedded in them that pops out and breaks the contact with the commutator to stop the brush running down to nothing. If you take the brushes out and see a dot on one of them, they're worn out.

Work throw away loads of grinders that have just worn the brushes down to the pin (bosch, metabo and dewalt) but they're all 110V so no use to me. I still have them apart for a look before they go back in the WEEE bin.....

I'll have to take another look at the brushes. Thanks.

 

[indykid]

If you're ever in a life or death pinch, if you dig the pin out, the brushes still work fine. Might help with diagnosis

 

[6ply]

If you're ever in a life or death pinch, if you dig the pin out, the brushes still work fine. Might help with diagnosis

I should have looked at both brushes and not just the one. Pretty damned obvious what's happening here and why it stopped so suddenly and without warning. Thanks.

 

[Turbo]

Does this grinder have a fast stop system?
Often these use electric braking to stop the disc quickly. This braking process is quite hard on the brushes as it puts a lot of current through them to stop the disc quickly.

I just changed a set of brushes on a hitachi wood chop saw that has not done a lot of work but the brushes were completely worn out.

 

[6ply]

Does this grinder have a fast stop system?

Only when I snag myself with a wire brush.

 

[6ply]

Those grinders have a spring built into the brushes so that when they wear to a certain point, the spring pops through and stops the grinder dead. Before damage to the commutator. Could be that.

I liked those old Bosch gws grinders.

Correct. See post #13