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Aug 19, 2011 11:19:32 GMT
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I was using my angle grinder yesterday and it just stopped. No shudder, bang, fizzle, smoke... nothing.
Checked the fuse in the plug, tried it from a known-working plug socket... not a sausage.
It's quite a good deWalt angle grinder and would cost £80.00 to replace.
Any ideas for a resurrection?
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10mpg
Club Retro Rides Member
Posts: 4,253
Club RR Member Number: 204
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Aug 19, 2011 11:41:52 GMT
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usually brushes or switch, both easy to replace and test once you pop it open (many will have the brushes accessible from the outside)
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The Internet, like all tools, if used improperly, can make a complete bo**cks of even the simplest jobs...
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Aug 19, 2011 12:01:00 GMT
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For some strange reason there seems to be a capicator between the swtich and the motor. But if I knew how to make these things then I'd be rich.
Brushes are good. Checked those and still plenty of life in them. Switch is good. So the only other thing between the switch and the motor is the capicator. It would probably work without it but maybe I'll try and get a replacment capicator as a first step. Must cost only a couple of squid at most.
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craig1010cc
Club Retro Rides Member
Posts: 2,998
Club RR Member Number: 35
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Aug 19, 2011 12:04:47 GMT
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Have you checked that a wire hasn't fractured in the flex? Does the motor spin ok?
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Aug 19, 2011 12:08:27 GMT
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Motor turns freely. I could check the flex but I think that's ok. I'm sure when I tried to turn it on just now it made a sort of whimper which I couldn't hear when the case was fully assembled. I'm fairly sure power is getting through the flex ok. Might continunity test between the terminal inside the grinder and the pole on the power socket. Will see if there is any break in the wire then. Little nervous about connecting both prongs of the mutli-meter to the 240v supply so not going to do that without a good reason to do so.
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abacus
Part of things
Posts: 24
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Aug 19, 2011 12:34:41 GMT
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"Have you checked that a wire hasn't fractured in the flex?" Usual cause, esp with De Walts for some reason. No need to connect with 240v to check continuity, btw
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Aug 19, 2011 13:10:19 GMT
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Obviously ;D
Continunity is alright in the flex.
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markbognor
South East
Posts: 9,970
Club RR Member Number: 56
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Aug 19, 2011 13:14:08 GMT
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Go and buy a new one. Thats a surefire way to get it working again
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Aug 19, 2011 13:47:40 GMT
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For the sake of just a small part why should I?
It seems deWalt offer a good spare parts service so I'm going to order a new switch which comes with the capicator already installed.
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Aug 19, 2011 14:07:25 GMT
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For the sake of just a small part why should I? It seems deWalt offer a good spare parts service so I'm going to order a new switch which comes with the capicator already installed. That's the spirit! Stop the buy-and-throw-away society What can - should be repaired and used again. Hell - we all do it with our cars, don't we? So why not do the same with a much simpler thing like an angle grinder? [X] pro fixing stuff
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Aug 19, 2011 17:04:45 GMT
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I'm no electrical expert, but could the capacitor be used for a soft start, as a buffer to stop the jerky start up of most grinders?
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MrSpeedy
East Midlands
www.vintagediesels.co.uk
Posts: 4,789
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Aug 19, 2011 17:06:46 GMT
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If it's a 240vac grinder (which I assume it is) a lot of electric motors need a capacitor to run and will not work without one
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10mpg
Club Retro Rides Member
Posts: 4,253
Club RR Member Number: 204
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Aug 19, 2011 18:04:14 GMT
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you get cap start and cap run motors, never seen one in a grinder, but that means nothing!
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The Internet, like all tools, if used improperly, can make a complete bo**cks of even the simplest jobs...
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Aug 19, 2011 18:59:47 GMT
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The capacitor's probably there to reduce interference from the motor.
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Aug 19, 2011 20:05:24 GMT
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I do remember something in the specifications from years ago about it having a smooth start/stop action.
I've ordered a new switch. I suppose it will arrive next week sometime.
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markbognor
South East
Posts: 9,970
Club RR Member Number: 56
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Aug 19, 2011 20:45:25 GMT
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For the sake of just a small part why should I? It seems deWalt offer a good spare parts service so I'm going to order a new switch which comes with the capicator already installed. That's the spirit! Stop the buy-and-throw-away society What can - should be repaired and used again. Hell - we all do it with our cars, don't we? So why not do the same with a much simpler thing like an angle grinder? [X] pro fixing stuff Wrong end of the stick there chaps, of course you should fix it, but i have occasionally found that once that path is exhausted and i've resorted to buying a new one the old device - often once tested again some time later - mysteriously works as it did before.
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Aug 19, 2011 21:51:06 GMT
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i've had a few dewalt tools do similar tricks, if you've had the brushes out completely and checked them then ignore this
the clever devils embed a spring in the brush, so when it wears to a certain level the spring is revealed and holds the brush off the commutator and the tool stops, it's to save the commutator from damage through arcing as the brush wears and the spring pressure is lost, however it usually happens just when you want the tool, so rip out the embedded spring and carry on, just order a new set of brushes and replace at your leisure.
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Ahh, well the replacement switch is on it's way. If that does not work then I'll get the brushes out and see.
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Last Edit: Aug 20, 2011 7:20:51 GMT by ejenner
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Aug 20, 2011 13:49:24 GMT
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So the only other thing between the switch and the motor is the capicator. It would probably work without it but maybe I'll try and get a replacment capicator as a first step. Must cost only a couple of squid at most. Capacitor smooths the flow of electric to the motor when you switch it on. Without it, it would blow the motor! ;D
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Aug 20, 2011 14:52:43 GMT
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Sorry if I sound like a grumpy g!t but there's a lot wrong with this thread!!
Fixing anything involves two stages: find the fault...then fix the fault.
So far, as far as I can see we still don't actually *know* what the fault is.
Sure you can use 'replacement' as a legitmate fault finding technique, but it gets expensive when you have to buy the replacement parts!
In general terms to fault find, you split the system in half and check that all the 'conditions' are correct at that point. Depending on the result, you then work forwards or backwards.
In the case of the grinder I'd check on the output side of the switch. If you know what you're doing you can check with it live and plugged into the mains I measuing AC volts. But if in *any* doubt at all, do it without being plugged in and use the continuity check.
If you've got continuity up to the switch (on both live and netural sides) you know the fault is in the motor area somewhere - windings, brushes, capicator.
If you don't have continuity then it will be the switch, lead plug (if it has one) or mains lead.
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