Lincoln Electric SAM400, SAM650 manual Recommended

E-5		TROUBLESHOOTING		E-5
	Observe all Safety Guidelines detailed throughout this manual
	PROBLEMS	POSSIBLE CAUSE		RECOMMENDED
	(SYMPTOMS)			COURSE OF ACTION
		FUNCTION PROBLEMS
Output without control -		Continuity test. (Note B Pg. E-2).		1.Make continuity test outlined in Step 3,
one mode				on page E-2 except turn voltage con-
				trol from maximum (0 ohms) to mini-
				mum (10,000 ohms).
				2.Replace Control Board #2. (Note A Pg. E-2).
Output without control -				l. Replace Control Board #2
both modes				2.Replace Control Board #1. (Note A Pg. E-2).
Output low in both modes -		Test rotor voltage (80-90 volts DC)		1.Rotor Voltage less than 80-90 volts DC
open circuit voltage low (CV and VV				a)Check Diodes D1 - D2 - D5 -D6. See
positions)				Procedure.
				b)Check SCR Bridge. See Procedure.
				c)Check resistance of rotor fields.
				Normal value about 14 ohms.
				2.Rotor Voltage Within Limits
				a)Check SCR Bridge. See Procedure.
				b)Check generator field coil resis-
				tance.
				1)Disconnect blue and brown
				field coil leads. Normal value
				about 10 ohms. One field coil
				open - 20 ohms. Both field
				coils open - infinite resistance.
Arc difficult to start in CV position		Test alternator outputs	(22-24	1.Set polarity switch in electrode positive
using low current and voltage		volts DC)		position.
(Characterized by large droplets, low				2.Check voltage between work stud and
frequency transfer)				positive alternator lead connected to
				input side of line contactor.
				a)Within Limits
				Check contactor contacts.
				b)Less than 22-24 volts DC
				Check three phase bridge recti-
				fier diodes D7 - D8 -D9 -D10 -
				D11 -D12. See Procedure.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.

SAM400 & 650