Lincoln Electric Cobramatic K2259-1, Operator'S Manual

Page: 18 / 44

Cobramatic
®
Owner’s Manual - page 8
Testing the Feeder
Testing the Input Power Circuits
The AC circuits are protected by pico-fuses F1 and F2 (see page 13 for
location). If these continually fail, especially when powering up the cabi-
net, remove the connectors for the components that draw on this power, J6
(Brake Solenoid), J7 (Slave Motor) and J5-3 & 4 (AC Contactor - if used)
from the P.C. Board. Replace fuses and retrigger system. If fuses does not
fail, isolate the problem by plugging in J4, J7, and J5-3,4 one at a time until
the fuses fail.
Testing the Speed Control
NOTE:
The gun should be tested prior to testing circuitry on the main board.
Gun amphenol must be connected to the Cobramatic ® to perform the
following tests.
To test the motor voltage circuit and measure how much voltage is being
delivered to the gun motor, place a voltmeter across diode test points
TP1 &
TP2 and pull gun trigger. A reading between 0 VDC & 28 VDC+/- should be
observed, as the gun potentiometer is varied (Figure 9).
Testing the Gun
Motor Check
Remove the amphenol connector from the cabinet.
Using the gun amphenol, check the resistance across pins “A” and “B”
(motor leads). The resistance across the motor should be between 5-10
ohms.
If an open circuit or short exists, check the motor leads and motor indepen-
dently.
Testing the Potentiometer - “W” Clocked
Using the gun amphenol, check the resistance across pin “D” (wiper) and
pin “C” . The resistance should vary from 0 - 5K ohms as you turn pot.
Check the resistance across pin “D” (wiper) and pin “G” . The resistance
should vary from 5K - 0 ohms as you turn pot.
Testing the Micro Switch
Using the gun amphenol, check for continuity across pins “E” and “F” when
the trigger is pressed.
Figure 9
Motor Voltage
Test Point
TP2
Motor Voltage
Test Point
TP1
Motor Demand
Test Point
TP3