Pic. 266. Measuring the length of a carbon brush.
Pic. 267. Soldering carbon brushes. The brushes must protrude to the specified length.
Rotor.If the current collector rings are dirty or oily, wipe them with a cloth soaked in "TRI". Scratches are polished with the finest sandpaper. To check the insulation, connect one end of the ohmmeter to the rotor core and the other end to the slip rings. The ohmmeter should show "infinity" (Pic. 268). If not, replace the entire rotor. To check the conductivity of the rotor winding, connect both ends of the ohmmeter to the slip rings. If the indication differs from 2.8-3.0 Ohm, replace the rotor (Pic. 269).
Pic. 268. Checking the rotor for contact with ground.
Pic. 269. Checking the breakage of the rotor target.
StatorWhen a short circuit occurs, most often due to overheating, the location of the damage is determined by sight. Otherwise. connect an ohmmeter to the phase wire and to the stator iron. The device should show "infinity" (Pic. 270). Otherwise, replace the stator. To check the stator conductivity, connect three wires in series with each other. If there is no reading, the circuit is broken (Pic. 271).
Pic. 270. Checking the stator for contact with ground
Pic. 271. Checking the stator for a break
Diodes.A qualified test of diodes in terms of pass-through voltage and determination of blocking current can only be determined using a special tester. If it is not available, use a regular tester. Connect the device at one end to the diode and the other to the diode board (Pic. 272). After this, swap the ends as shown in the bottom picture. In this case, the positive diodes are checked. The negative diodes on the other side are tested in the same way.
Pic. 272.Checking diodes. Connect the ohmmeter first, as in the upper figure, and then, as in the lower figure.
For both tests, the diodes should conduct in only one direction, i.e. in the upper figure the ohmmeter needle should deflect, and in the lower figure it should show "infinity". If the diode conducts current in both directions, it is broken. If it does not conduct current in either direction, then the diode is open. The remaining diodes are checked in the same way.