NANO

ELECTRICAL 621 ELECTRICAL 12. BENCH INSPECTION After dismantling the unit conducts the following checks Brush check Minimum required Brush Length: 7.5 mm It the brushes are below the minimum required length renews the brushes in sets not individually. De’ solders the brush lead assy. Insert New brush assembly and solder. Make sure that the brushes move freely inside the brush box. • Slip ring check Clean slip ring surface with a fine piece of cloth and ensure that the surface is smooth and clean. If the surface is very rough and cannot be polished, replace the rotor assembly. There should not be any trace of oil or grease on the slip ring surface. • Bearing check (SRE &DE) Bearing should rotate freely without any excessive play. If play is observed, the bearings should be replaced. • Rotor assembly check : Resistance Check: Use ohmmeter 0-10 ohm range and connect as shown in fig. Connect the probes of the meter to the slip ring. The value should be 2.47 – 2.73 ohms at 20°C . If value is outside this limit, change the rotor assembly. • Rotor ground test