Intermittent starting on SDS hammer drill

[Barnjet]

Hi Sparkies, newbie here needing some advice please

My 1100W SDS hammer drill sometimes starts, sometimes dead. So far fault diagnosis (loose connections, voltage and continuity checks) has ruled out switch, commutator and rotor armature windings. My suspicion has fallen on either the brushes and/or the capacitor. The brushes seem to be ok and both still have good spring pressure.



I have no direct way of measuring capacitance, but using the ohmmeter function on an analogue multimeter, I would expect to see a temporary deflection towards 0 ohms then back to infinity. But nothing across leads 1 and 2 or 2 and 3. There is a very minor flick across leads 1 and 3.



I could get a replacement capacitor for about £3.50, do the experts thinks this is my best bet.

Thanks in advance

 

[westward10]

Have you checked continuity of the cable whilst flexing it at the same time.

 

[Barnjet]

Have you checked continuity of the cable whilst flexing it at the same time.

Thanks, I can see where you’re coming from. Not checked but will do and report back

 

[telectrix]

with the brushes in their normal position, clipmeter leads (set on ohms) one on each brush holder terminal. you should get a low readingof a few ohms. slowly rotate the armature. as each comm. segment is in contact with a brush, reading should be same in any positionof the armature. for the sake of £3.50, it's worth trying a new cap.

 

[snowhead]

It's almost always the power lead into the drill.
It'll be 1 core broken and making bad contact close to the handle, where it gets wound up tightly for storage.

Start at the drill and pull the outer sheath back till you find it.

 

[Barnjet]

Have you checked continuity of the cable whilst flexing it at the same time.

Amazing Westward10, I think you've nailed it!! Definitely a break in the Live wire, hopefully you can see the "puncture" hole on the photo, presumably caused by arcing.




When I stripped this section, the Live wire clearly showed fatigue failure. And hence the cause of the intermittent start/stop.




For repair, I think I will in-line splice the Live, as I don't have any spare termination connectors (see below). Unless you guys think this a bad move.


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It's almost always the power lead into the drill.
It'll be 1 core broken and making bad contact close to the handle, where it gets wound up tightly for storage.

Start at the drill and pull the outer sheath back till you find it.

You got it in one as well Snowhead! Thanks

 

[westward10]

Could have been worse you could have stripped it all down before you found it

 

[Barnjet]

All now working as it should My thanks to all the contributors.

There is no substitute for experience

 

[ipf]

All now working as it should My thanks to all the contributors.

There is no substitute for experience

An obvous one, really. Just hope you didn't put a connector on it and tape it up.
No splicing...…CHANGE THE LEAD! or cut back and reconnect properly.

 

[telectrix]

or cut back and in the absence of push-on connectors, solder the terminals.

 

[Barnjet]

An obvous one, really. Just hope you didn't put a connector on it and tape it up.
No splicing...…CHANGE THE LEAD! or cut back and reconnect properly.

Don’t worry, I changed my mind on the the repair ? No connector, no splicing, no tape. Just cut back to good and terminated correctly. However, storage case will need redesign, as it places acute bend radius on power cable, which over time obviously caused the failure.

 

[DPG]

Don’t worry, I changed my mind on the the repair ? No connector, no splicing, no tape. Just cut back to good and terminated correctly. However, storage case will need redesign, as it places acute bend radius on power cable, which over time obviously caused the failure.

Drill now only has a 3 inch long mains cable though