Lincoln Electric 11519 Service Manual page 93

F-47
SCR OUTPUT RECTIFIER REMOVAL AND REPLACEMENT (continued)
FIGURE F.15 — RIGHT HEAT SINK LEAD DISCONNECTION
SCR
ASSEMBLY
LEAD
#320
LEAD
#209S
LEAD
X4
5. Remove lead #209S and transformer lead X4
from the right side heat sink using a 1/2 in.
socket wrench and 1/2 in. open end wrench.
See Figure F.15.
6. Unplug the SCR gate leads G1 and G2 (see
wire markers and Wiring Diagram).
7. Remove the four nuts holding the SCR assem-
bly to the floor of the machine using a 3/8 in.
nutdriver.
8. Clear the leads and carefully remove the SCR
rectifier assembly.
TROUBLESHOOTING AND REPAIR
SCR DIODE
LEAD
Power MIG® 255XT
LEAD
#320B
NOTE: When installing the SCR rectifier assembly,
apply a thin coating of Dow Corning #340
compound to the electrical connections.
9. Unplug leads 320 and 320B from the SCR
heat sink thermostat on the right side at the
SCR assembly.
10. Reassemble the SCR assembly in the reverse
order.
F-47