Lincoln Electric SAM400, SAM650 manual Loss of Output in Both Modes of Operation

LOSS OF OUTPUT IN BOTH MODES OF OPERATION

(Constant and Variable Voltage Positions)

Test Alternator Rotor Voltage (80- 90 Volts DC) Lead #222 to #1

1.If rotor voltage present go to Step 9. If no rotor voltage go to Step 2.

2.Lightly sand slip rings and reseat brush- es.

3.Flash rotor fields.

a)Turn machine off.

b)Use a 12 to 24 volt battery.

c)Apply voltage for 15 seconds, negative lead to #1, positive lead to #222 at alter- nator terminal strip.

CAUTION: Wrong polarity may dam-

age diodes.

4.Jumper leads #75 to #222 -- replace alternator thermostats if this produces output.

5.Continuity check - (Note B Pg. E-2).

a)Remove rotor brushes.

b)Disconnect #212 and #214 from alterna- tor terminal strip.

c)Remove all leads from #1 and #2 on con- trol box terminal strip.

d)Remove both Control Boards.

e)Check continuity from #214 to #1 and #212 to #1 with the positive lead on #214 and #212. This should read about 27,000 ohms. If shorted, check C-7 for a short. If all right, check D5 and D6. See Procedure

6.SCR Bridge Check.-See Procedure

7.Three phase bridge rectifier check.

a)Remove leads from three phase bridge rectifier assembly and check diodes (D7 - D8 - D9 - D10 - D11 - D12) See Procedure

8.Alternator continuity check - (Note B Pg. E-2).

a)Disconnect lead #212 and #214 and check winding for continuity.

b)Remove one rotor brush, check continuity of rotor field.

NOTE: Checking resistance of rotor field may cancel residual magnetism in the rotor iron. Repeat Step 3, "Flash Rotor Fields".

9.If Rotor Voltage is present check voltage between lead #75 and Pin #227 at the rear of Control Board #2 connector. (Approximately 15 to 22 volts DC.)