Lincoln Electric SAM650, SAM400 manual Control Boards. Note a Pg. E-2

E-4

TROUBLESHOOTING

E-4

Observe all Safety Guidelines detailed throughout this manual

PROBLEMS

POSSIBLE CAUSE

RECOMMENDED

(SYMPTOMS)

COURSE OF ACTION

FUNCTION PROBLEMS

10. Voltage higher than 22 volts DC.

a) If between 22 and 100 volts, replace both

Control Boards. (Note A Pg. E-2).

b)

If voltage is greater than 100 volts:

1)Check diode D-4 for a short. See Procedure

2)Replace both Control Boards but only if

voltage between Pin #75 and #227 is

less than 100 volts DC.

11. Voltage less than 15 volts DC, replace

Control Board #1. (Note A Pg. E-2).

12.

Voltage within limits.

a) Check SCR Bridge. See Procedure

b)

Check generator field coil resistance.

1)Disconnect blue and brown field coil

leads. Resistance should be about 10

ohms.

c) Replace Control Board #1. (Note A Pg. E-2).

d) Check Control Board #2 by following Step

2, Pg E-2.

Output without control - one mode only

SCR Bridge Test (See Procedure)

If bridge tests good proceed to next step.

(Constant or Variable Voltage)

Output without control - both modes

Continuity test. (Note B Pg. E-2).

1.

Turn machine off.

(Constant and Variable Voltage)

2.

Remove both Control Boards.

3.

Place electrode polarity switch in con-

stant voltage positive position.

4. Toggle switch to mode in question.

5.

Check continuity of the following

(Note

B Pg. E-2):

a) Constant Voltage

1)Work to Pin #217 of the connector for

Control Board #2.

2)Pin #203 of the connector for Control

Board #2 to Pin #216 of the connector

for Control Board #1.

3)Between corresponding numbers of the

connectors for both Control

Boards,

Pin #75, 216 and 227.

b)

Variable Voltage

1)Blue field lead to Pin #201 of the con-

nector for Control Board #2.

2)Pin #202 of the connector for Control

Board #2 to Pin #216 of the connector

for Control Board #1.

3)Between corresponding pins of the

connectors of both Control Boards, Pin

#75, 216 and 227.