isoIsolating electrics for welding

[duTch]

 Hey guys, was just thinking if  when electrically welding (mig tacks) on the frame (or specifically engine pipes) if the dynamo and maggie are OK in place after isolating the battery and remove the earth brush from the Maggie. .or best to  completely remove both units. ..?
 I know what can happen if nothing's disconnected  !

[sparx]

The big issue is causing damage to semiconductor devices, such as an electronic regulator for the dynamo.
  Where I sub-contract my services as an auto-electrician a lot of welding is done on modern trucks, which are cram-packed with electronics. The procedure carried out is that stipulated by Mercedes Benz, to leave everything connected with the exception of the battery leads, which are bolted together. That way any stray voltage from the welder is on both sides of any devices, so the potential difference is zero.
  If you're welding the frame the welder earth clamp should be on the frame as close to the welding point as possible.
 

[muskrat]

Good info there sparx. I have only ever disconnected the battery and unplugged the dynamo. Haven't cooked anything yet but will go with your method in future.
Cheers

[bsa-bill]

very useful post that is sparx

[duTch]

 Yea ok Sparx, points noted but not quite what I expected. ...not a Merc. and I don't have any electronics as such; mechanical reg. and magneto, no fairy lights at all... main concern being the magneto- is Any chance of anything frying if I pull the plug leads and the earth brush and leave unit in situ. ..?
 And yes I'd clamp an earth close to work zone, if I do it will only be a couple of locating tacks and remove the pipes to finish it.

[sparx]

 Yea ok Sparx, points noted but not quite what I expected. ...not a Merc. and I don't have any electronics as such; mechanical reg. and magneto, no fairy lights at all... main concern being the magneto- is Any chance of anything frying if I pull the plug leads and the earth brush and leave unit in situ. ..?
 

Nothing in the maggy that can get damaged by welding on the frame duTch, assuming you're not putting the welder earth on the maggy drive  .
 The only part that is remotely "electronic" is the capacitor. If you're concerned about damaging that leave the earth brush in and make sure the points are closed.
   Disconnecting the plug leads is completely unnecessary but if your happier doing it Then do so. It will do no harm.....