Troubleshooting & repair – Lincoln Electric POWER MIG 255 SVM144-B User Manual
Page 90
POWER MIG 255
TROUBLESHOOTING & REPAIR
F-52
F-52
6. Remove the two transformer secondary
leads X2 and X3 (braided copper strap)
from the negative capacitor bank buss
bar using two 1/2 in. open end wrench-
es.
7. Disconnect and label all transformer
leads from the reconnect panel using a
3/8 in. open end wrench.
8. Disconnect and label all leads from the
input power switch.
9. Remove the power switch.
10. Disconnect thermostat leads #320 and
#320B from the SCR Rectifier.
PROCEDURE
1. Disconnect main input power to the
machine.
2. Remove the case side panels using a
3/8 in. nutdriver.
3. Test that the capacitors are discharged
using a volt ohmmeter. Polarity must
be observed.
4. Remove lead X1 from the left side SCR
heat sink assembly using a 1/2 in. sock-
et wrench, extender and universal
adapter. See Figure F.17.
5. Remove lead X4 from the right side
heat sink assembly using a 1/2 in. sock-
et wrench, extender and universal
adapter.
FIGURE F.17 — MAIN TRANSFORMER REMOVAL.
OUTPUT
CHOKE
LEAD
LEAD
X1
LEAD
X4
LEADS
X2 AND X3
POWER
ENHANCEMENT
CHOKE
MAIN
TRANSFORMER
PLUG-IN LEADS ARE
NOT SHOWN FOR
CLARITY.
NOTE:
OUTPUT
CHOKE
POSITIVE
LEAD
MAIN TRANSFORMER AND OUTPUT CHOKE
REMOVAL AND REPLACEMENT (continued)