Lincoln Electric INVERTEC SVM129-B - Manual (Page 100)

TROUBLESHOOTING & REPAIR
F-62 F-62
INVERTEC® STT® & STT® II
SWITCH BOARD REPLACEMENT (continued)
TEST AFTER REPAIR OF SWITCH
BOARDS AND/OR CAPACITORS
The following test must be performed after the
switch boards and/or the capacitors have been
replaced.
NOTE: Always make sure that switch boards are
changed in matched pairs. Never mix an
old style (different part number) switch
board with a new style (new part num-
ber).
TEST PROCEDURE
1. Turn main power OFF.
2. Perform Input Filter Capacitor Discharge
Procedure. See the Maintenance section.
ELECTRIC SHOCK can
kill.
• Before continuing with the
test procedure, perform
the capacitor discharge
procedure to avoid electric
shock.
3. Connect a shorting conductor across termi-
nals 14 and 53 of the protection PC board.
See Figure F.29.
4. Set an ANALOG ohmmeter to X1000 range
and place the probes on terminals 9 (+) and
12 (–) of one switch board. The meter will
show the capacitors charging up and may
take a minute or so to stabilize. The final
meter reading should not exceed 8600 ohms
(8.6 on the scale).
5. Test the other switch board the same way.
NOTE: Repeat the Input Filter Capacitor
Discharge Procedure.
6. Remove the shorting conductor set up in step
3.
7. Replace 20 amp fuses with 5-amp fuses in
the input supply fuse holders.
NOTE: These fuses should be installed to pro-
tect against excessive current flow
caused by a short circuit during the pro-
cedure.
WARNING
FIGURE F.29 — SHORTING TERMINALS 14 AND 53 OF PROTECTION BOARD
L7915-[ ] PROTECTION
53 14
JUMPER TERMINALS
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