MK Products CobraTig-150 Manual

CobraTig
®
150
Calibration Procedure
Document 031-0181 Rev B
CAUTION
Performing the following Tests and Calibration require the operator to be
near HIGH VOLTAGES and HIGH CURRENTS. Operator must be familia r
with working in this environment and exercise caution during this
procedure to avoid any shock hazards.
MK Products,
Inc.
16882 Armstrong Ave., Irvine, CA 92606 [phone]

1. EQUIPMENT NEEDED
o CobraTig 150 and Orbital Weldhead.
o Calibration Kit (p/n 005-0251)
o 30V / 5A DC External Power Supply and Banana Test Leads
o Digital MultiMeter (Fluke 8060A or Equivalent) and Test Leads
o Water Recirculator
o Small Plastic Flathead Screwdriver
o 1/4” Hex Wrench
o Glyptol Insulating Varnish
o Feeler Gauge
o Wire Brush
External DC Power Supply Digital Multi-Meter Glyptol
Calibration Kit ¼ Hex Wrench and Screw Driver

Please read this procedure in its entirety before
performing any work
2. EQUIPMENT SETUP
CobraTig150
Determine input power available and wire input power plug accordingly if not
already provided that way. See Appendix A for proper configuration of input
power and internal jumper selections.
Do not apply power to the CobraTig 150 until directed to do so.
Calibration Weld Box Load
Adjust torch in load box for proper weld gap (.065~1/10 in) with feeler gauge and
ensure tungsten and plate surface are clean, use wire brush if necessary. Also
make sure the tungsten is 1/16 in .
Do not connect load to CobraTig150 until directed to do so.

3. COBRATIG-150 CALIBRA TION
3.1
Current-Voltage-Demand Offset Adjustment
Before
starting Calibration, print out the current Weldhead and Motor
Calibration from the calibration menu (Later this can be compared with your
new calibration da ta.)
Meter (DMM) Setting - Scale: mV, Mode: DC
3.1.1 Using a ¼” hex wrench, remove all the screws from the cover of
the CobraTig150. Remove cover by pulling the sides slightly away
from the machine, and lifting upward. This is to ensure that the
louvers do not catch on any of the components or wires inside.
3.1.2 Locate the test points on the left side of the CobraTig150, on the
Power Supply Control Board (second board down from the top.)
Place the Meter GND(-) lead on TP1 and the Meter POS(+) lead
on TP3. (Figure 1)
Fig. 1 – TP3 Voltage adjustment

3.1.3 Apply input power to CobraTig150 and switch power on with
breaker on back of unit. Using the small plastic flathead
screwdriver, Adjust R24 (Current Offset) of the Power Supply
Control Board until a reading in the range of (-2 mV to +2mV) is
obtained on meter. (Figure 2)
Fig. 2 – Trimpot R24 is used to adjust voltage at TP3
NOTE If your CobraTig has only one Trimpot (instead of three, it is
an older model). The one trimpot is R24. After completing step 3.1.3, skip
ahead to step 3.1.9.
3.1.4 Leaving the Meter GND(-) lead on TP1, move the Meter POS(+) to
TP7. (Figure 3)
Fig. 3 – TP7 Voltage adjustment
R24
Location

3.1.5 Adjust R130 (Voltage offset) until a reading in the range of
(-2 mV to +2mV) is obtained on meter. (Figure 4)
Fig. 4 – Trimpot R130 is used to adjust voltage at TP7
3.1.6 Leaving the Meter GND(-) lead on TP1, move the Meter POS(+) to
TP8.(Figure 5)
Fig. 5 – TP8 Voltage adjustment
3.1.7 Adjust R139 (Demand Offset) until a reading in the range of
(-2 mV to +2mV) is obtained on meter. (Figure 6)
Fig. 6 – Trimpot R139 is used to adjust voltage at TP8
R130
Location
R139
Location

3.1.8 Re-Check all three test points (TP3, TP7, and TP8) to
verify that the settings are maintained. Make additional
adjustments if needed.
Notes:
R24 is used to adjust voltage at TP3
R130 is used to adjust voltage at TP7
R139 is used to adjust voltage at TP8
3.1.9 Remove all Meter leads from Test Points in CobraTig150. Use
Glyptol to seal the trimpot settings when done. (Figure 7)
Fig. 7 Use Glyptol to seal three (3) trimpot.

NOTE: Connect the Calibration Kit Weld Power & Gas Cables and
Weldhead Control Cable to the back of the Cobratig150. (See Appendix B)
(Figure 8)
Fig. 8 - Calibration Setup
3.2 Weldhead Motor
Calibration
The COBRATIG-150 Software allows push-button adjustments of the
COBRATIG-150 calibration parameters.
3.2.1 From the MAIN MENU, press the CALIB MENU [F7] key.
3.2.2 From the CALIBRATION MENU, Press the MOTOR CALIB
[F6]
key. The default settings are High=6 and Low=2. Leave these
speeds as they are for most cases.
3.2.3 Then press the START CALIB [F8] key. Verify visually that the
weldhead rotor is turning. The CobraTig150 motor compensation
circuit will automatically calibrate for that Weldhead connected.
NOTE: The Motor
Calibration data is updated after two complete passes of
the rotor, aborting at any time before this will cause the Weldhead to be un-
calibrated.

3.3 Arc Voltage Calibration
Connect the DC power supply to the Input Voltage connectors of the Calibration Kit
shunt box. (POS to RED+, NEG to BLACK-). Connect voltage meter DMM
(Digital Multi Meter) across supply leads to monitor voltage if your DC supply does
not have a digital display.(See App e ndix C / Figure 9)
Meter (DMM) Setting - Scale: Volts (V), Mode: DC
Fig. 9 – Voltage Calibration Setup
3.3.1 From the MAIN MENU, Press the CALIB MENU [F7] key.
3.3.2 Inject exactly 1.80VDC from the DC power supply with digital display
or inject 1.80VDC +/-1% or [1.782VDC to 1.818VDC] from DC power
supply without digital display. Then press the 1.8VDC CALIB [F3]
key to accept input.
3.3.3 Inject exactly 18.00 VDC from the DC power supply with digital
display or inject 18.00VDC +/-0.5% or [17.9VDC to 18.1VDC] from
DC power supply without digital display. Then press the 18VDC
CALIB [F4] key to accept input.
NOTE: Arc Voltage
Calibration is updated only after pressing the 18VDC
CALIB [F4] key, aborting at any time before this will cause the Arc Voltag e
to be un-c a librated.

3.4 Current
Calibration
CAUTION:
Disconnect DC power supply and/or DMM from their power
source until an Arc is established.
3.4.1 Connect leads from the DMM (POS to RED+) (NEG to BLACK-)
to the Current Shunt of the Calibration Kit Shunt Box, make sure
meter is off until weld arc is started. Verify that the Calibration Kit is
connected to the CobraTig150 weld terminals. (See Appendix D)
3.4.2 From the CALIBRATION MENU, press the CURRENT START
[F7] key to start the Current Calibration sequence. Once an Arc is
established, turn the DMM back on.
Meter (DMM) Setting - Scale: mV, Mode: DC
3.4.3 The current output should now be at approximate 10 Amps. Adjust
the output current as read across the Calibration Kit shunt with the
DMM by pressing ADJUST UP [F5] or ADJUST DOWN [F10]
keys until it is in the range of (2.50mV to 2.59mV). The voltage
reading should be as close to 2.59mV as possible without going
over. Then press the 10A CALIB [F8] key to accept when right.
3.4.4 The current output should now be at approximate 80 Amps. Adjust
the output current as read across the Calibration Kit shunt with the
DMM by pressing ADJUST UP [F5] or ADJUST DOWN [F10]
keys until it is in the range of 19.97mV to 20.034mV. Then press
the 80A CALIB [F9]key to accept when right.
Repeat 3.4.3 ~ 3.4.4 for second time, unit should acknowledge completion.
NOTE: The Current
Calibration is updated only after pressing the 80A
CALIB [F9]key the second time. Aborting at any time before this will cause
the Weld Current to be un-calibrated.
3.4.5 Press the MAIN MENU [F2] key. Press the PRINT MENU
[F6 ] key. Press CALIB REPORT [F9] key. Save the printout
for reference.
Disconnect all Test Equipment from CobraTig150, your MK Welder is now
calibrated and ready to weld.