Lincoln Electric INVERTEC SVM129-B Service Manual page 85

F-47
CR2
309A
7. If the Capacitor Balance Test is OK and
more than 5VDC is present at leads #311 to
#313 (Step 6), the protection PC board may
be faulty.
NOTE: The above voltage checks pertain only
to the over voltage signal from the protection
PC board to the power PC board. The capaci-
tor precharge circuits are also incorporated
within the protection PC board. If the problem
has not been identified, carefully proceed with
the following steps.
8. Remove input power to the Invertec STT
machine.
9. Perform the Input Filter Capacitor Discharge
Procedure. See the Maintenance section.
WARNING
ELECTRIC SHOCK can kill.
10. Locate and remove leads #309 and #309A
from CR1 and CR2 relays. See Figure
F.18.
TROUBLESHOOTING & REPAIR
PROTECTION BOARD TEST (continued)
FIGURE F.18 - LEADS #309, #309A AT CR1, CR2 RELAYS
• Before continuing with
the test procedure, per-
form the capacitor dis-
charge procedure
avoid electric shock.
INVERTEC STT
CR1
WARNING
ELECTRIC SHOCK can kill.
11. Apply correct input power and turn ON the
machine.
12. Check for approximately 12VDC from plug
J15 pin 1 (lead #314)(+) to plug J15 pin 4
(lead#315) (-). See Figure F.17.
13. Check for approximately 12VDC from plug
J15 pin 3 (lead #316)(+) to plug J15 pin 6
(lead#317) (-). See Figure F.17.
14. If a low voltage is present in either steps 12
or 13 (approximately 1VDC), perform the
Capacitor Balance Test.
15. If the Capacitor Balance Test is OK, the
protection PC board may be faulty.
to
16. Be certain to replace leads #309 and #309A
onto the CR1 and CR2 relays.
17. After all tests are completed, install the
case wraparound cover.
309
• With input power ON,
there are high voltages
inside the machine. Do
not reach into the machine
or touch any internal part.
F-47