Lincoln Electric SQUARE WAVE TIG 355 Service Manual page 108

F-56
Test Points
3J13 to 5J13
4J13 to 5J13
1J13 to 2J13
R11 to 5J13
R32 to 5J13
R13 to 5J13
R66 to 5J13
R8 to 5J13
TROUBLESHOOTING AND REPAIR
CONTROL PC BOARD TEST (continued)
CONTROL PC BOARD VOLTAGE TEST POINTS CHART
Signals Being
Checked
Regulated +15VDC
supply to control
board
Regulated -15VDC
supply to control
board
Unregulated DC
supply to control
board
Low logic signal for
gas/water valve
Low logic signal for
interlock control
Low logic signal
for high frequency
Low logic signal for
DC OCV Boost
(CR3) relay
Low logic signal for
AC OCV Boost
(CR2) relay
SQUARE WAVE TIG 355
Expected Conditions
Reading for Test
+15VDC
-15VDC
+12VDC
0 - 2 VDC TIG Mode
Arc Start Switch or
Amptrol must be
activated
0 - 2 VDC If input contactor is
staying closed signal
will normally be low.
0 - 2 VDC CAUTION: High
frequency may
damage test
equipment.
Use analog
volt/ohmmeter
TIG Mode
High frequency is
active after gas
preflow time.
0 - 2 VDC Stick Mode
DC Mode
0 - 2 VDC Stick Mode
AC Mode
F-56
Special
None
None
None