Lincoln Electric PRO-CUT 55 Service Manual page 60

F-22
OUTPUT POWER BOARD RESISTANCE TEST (continued)
TEST POINTS
+Probe J33-Pin4
–Probe Terminal B11
+Probe Terminal B11
–Probe J33-Pin4
+Probe J33-Pin4
–Probe Terminal B12
+Probe Terminal B12
–Probe J33-Pin4
+Probe R5 Test Point
–Probe Terminal B1
+Probe Terminal B1
–Probe R5 Test Point
+Probe R5 Test Point
-Probe Terminal B2
+Probe Terminal B2
–Probe R5 Test Point
+Probe R5 Test Point
–Probe J32-Pin14
+Probe J32-Pin14
–Probe R5 Test Point
6. If any of the resistance checks are not correct, the
output power board is faulty. Replace. See the
Output Power Board Removal and Replacement
Procedure.
7. If the output power board "passes" the resistance
test, the power diode and transistor portion of the
board is good. However, other circuits on the
power board may be faulty. These circuits are NOT
readily tested or serviceable.
TROUBLESHOOTING & REPAIR
TABLE F.4 - OUTPUT POWER BOARD RESISTANCE
to
to
to
to
to
to
to
to
to
to
CIRCUIT OR
COMPONENT(S)
BEING TESTED
Diode A1
and
associated trace
Diode A1
and
associated trace
Diode A1
and
associated trace
Diode A1
and
associated trace
Diode A2
and
associated trace
Diode A2
and
associated trace
Diode A2
and
associated trace
Diode A2
and
associated trace
Transistor A2
and
associated trace
Transistor A2
and
associated trace
8. Reconnect the leads and plugs previously
removed.
EXPECTED RESISTANCE
Less than
100 ohms
Greater than
1000 ohms
Less than
100 ohms
Greater than
1000 ohms
Less than
100 ohms
Greater than
1000 ohms
Less than
100 ohms
Greater than
1000 ohms
Less than
100 ohms
Greater than
1000 ohms
F-22