Lincoln Electric INVERTEC IM526-B Operator's Manual page 18

Step Test
5 Snubber
Resistors
Disconnect leads
401, 402, 403 and
404 from Switch
PC Board
6 Output diodes
Remove output
load
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, con-
tact your local Authorized Field Service Facility for technical troubleshooting assistance before you proceed.
Check
Lead 401 to terminal 25 ohms
12
>30 ohms
<20 ohms
25 ohms
Lead 402 to terminal
9 >30 ohms
<20 ohms
25 ohms
Lead 403 to terminal >30 ohms
12 <20 ohms
25 ohms
>30 ohms
Lead 404 to terminal <20 ohms
9
<100 ohms
+ output plug (pos)
to
- output plug (neg) >200 ohms
Test
Conclusion
Result
OK
R4 open
R4 shorted
OK
R5 open
R5 shorted
OK
R6 open
R6 shorted
OK
R7 open
R7 shorted
Shorted output
diode D1 thru
D12
Output diodes OK
CAUTION
– –
18
Next
Test
Step Repair Action
cont
Replace R4
cont
Replace R5
cont
Replace R6
cont
Replace R7
Test individually