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Discussion for the DeWALT DC940 Type 1 Drill / Driver
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Question: Dewalt Dc940 Repair
Hi I am working on a dewalt 12v xrp drill/driver. It has poor performance and burning odor along with some smoke. Near the brushes/armature I can see what looks like ignition/sparks and after taking off the rear cap the end is very hot. The brushes look to be in poor condition and possibly the armature where it contacts the brushes as well. I was wondering how to remove the brush and holder assembly from the motor and pinion assembly. Any help will be greatly appreciated. Thanks. Jordan.
Hi Jordan, The tool uses what called a brush cartridge which you gently pry out of the housing as an assembly.Hope that helps.
Thank You very much! That helps. I got them out and cleaned them and the commutator. There was significant build up around the brushes and in the commutator grooves. Looks like grease getting in from the transmission area. I did some more tinkering and found that the commutator gets red hot instantly where the brushes make contact. The brushes are beveled, angled long-ways(shorter to the rear), almost like the armature is out of round, and somewhat scored. This doesn't seem normal but I thought I would ask. I ordered 2 brush assemblies but I am beginning to think I need a motor and pinion assembly because the contact area is worn down nearly 1/16" from the rest of the armature. Do you think I need a new motor and pinion assembly? On first thought I was thinking "Too much votage getting to the brushes!" But mabeye it is because they are not making good contact. Again thanks for the help so far but can you help me again? Jordan.
Hi Jordan,Yes replace the whole motor assembly.We use a load tester to check that out but 80% of the time the armature is shorted.The grease that your talking about is molly grease from the transmission and your right it leaks out some times.Good luck.
Thanks a lot. I will try it when i get the parts in. If it still gets red hot I would have to guess the swith is bad. In the mean time, I will try and hotwire the motor with brushes attatched and installed in the drill with the transmission off.(unless that is a bad idea). I sure hope you are around in the future to help. Thanks.
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