Lincoln Electric IDEALARC DC-1500 Service Manual page 73

F-39
STATIC SCR TEST PROCEDURE (continued)
FIGURE F.14 – SCR/HEATSINK LOCATION(S) (VIEWED FROM FRONT)
B A R J U M P E R C A T H O D E H E A T S I N K C A T H O D E T O P S C R A N O D E H E A T S I N K B O T T O M S C R H E A T S I N K C A T H O D E T O P S C R G A T E L E A D S & S N U B B E R B O T T O M S C R
T O P S C R A N O D E H E A T S I N K
TOP SCR
CATHODE
HEATSINK
CATHODE
JUMPER
BAR
BOTTOM SCR
ANODE
HEATSINK
NOTE: DO NOT DISASSEMBLE THE HEAT
SINKS. THIS TYPE OF SCR NEEDS TO
BE COMPRESSED BETWEEN THE FAC-
TORY HEATSINK IN ORDER TO CON-
DUCT CURRENT.
3. Using an analog ohmmeter, test the resistance
from anode to cathode of SCR 1. Reverse the
meter leads and check from cathode to anode
of SCR 1. (R x 1000 SCALE)
a. If a low resistance is indicated in either
direction, disconnect the associated
snubber board mounted on SCR inside
mounting channel. See wiring diagram
and retest SCR 1. If a low resistance is
still indicated, SCR 1 is faulty -
Replace. If a very high or infinite resis-
tance is indicated without the snubber
circuit, then replace the snubber circuit,
See Figure F.14.
TROUBLESHOOTING AND REPAIR
IDEALARC® DC-1500
4. Repeat Step 4 testing SCR 2, SCR 3, SCR 4,
SCR 5, and SCR 6.
NOTE: To further check the SCRs' functions use
an SCR tester and proceed to Active SCR
Test.
F-39
TOP SCR
ANODE
HEATSINK
TOP SCR
GATE LEADS
& SNUBBER
BOTTOM SCR
CATHODE
HEATSINK