Figure 106. Undercutting mica with undercutter.
1 Commutator
3 Good undercutting
2 Poor undercutting
Figure 107. Samples of good and bad undercutting.
commutator segment in turn (fig. 109). If the lamp lights, a ground is present and the armature must be
replaced.
Note. Do not touch probes to bearing or brush surfaces, because an arc will mar the finish.
(h) Check the armature for short circuits by placing it on a growler (17-G-5940) and holding a thin steel strip
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