Bosch PEX400 problem.

[Mark S.]

My trust Bosch PEX400 sander is experiencing difficulties. :-)

I was using it a few weeks ago and ran out of the sanding discs so bought some from a local place as everyone else was shut etc. but they only had some bigger ones. Being an idiot I cut them to size and halfway through using them the lack of matching dust and what I now realise cooling air meant it overheated and melted the lugs on the rubber backing disc.

I finally got around to buying a couple of new ones, put one on with the right sanding discs this time but the sanders not running properly.

It powers up and spins but there's no "force" to it, as soon as you apply pressure to the sanding sheet it stops even on full speed it's struggling to work. If you switch it on at low speed it's making a noise and doesn't start. It does sometimes pick up speed and then "coughs" but still doesn't work right.

Is it knackered?

Brushes done in or the motors burnt out etc. I have had it apart to have a look, cleaned the contacts etc. but can't see anything physically wrong with it.

Mark S.

[Grunff]

It's likely you've melted some of the windings together. Either that or it's just burnt brushes/commutator - but my money's on the windings.

[Mark S.]

I did take the brushes out but they looked ok so I guess it's fried. :-(

Looks like I'll have to be borrowing the PEX400 I bought my dad for Christmas. ;-)

Mark S.

[Alan Campbell]

Hi,

If the windings had shorted on each other the motor would make a distinctive noise - difficult to describe but a sort of loud electrical buzzing noise. I would also imagine you would have smelled burning at the time you did the damage. It doesn't sound like you have these symptoms so perhaps all is not lost. I would check that the motor rotates freely and that there is nothing sticking at the business end of the sander and also that the fan on the armature isn't stuck to the casing.

Your problem also sounds a little like the speed controller has gone although I'm not convinced the extra load would have done it in. You could try bypassing it to be sure.

Failing that - take it to a local repair place. I know we are a throw away society but they should be able to tell you in no time if it is knackered.

Let us know how you get on.

Alan.

[Mark S.]

I had it to bits on the table again yesterday and it all looks "ok", ie. I can't see anything that is burnt or damaged.

I'm not going to throw it away as it's a good sander and has stood upto some serious use like when I sanded every bit of wood (second hand so free and recycling) for my fence etc.

I'll find somewhere local and see what they think.

Mark S.