MK Products Pulse+ - Manual (Page 18)

Pulse+ Owner's Manual Page 18
6.1 TESTING THE CURRENT SWITCH
When current flows through the buss bar, it creates a magnetic field. This
magnetic field causes the current switch, which is normally open, to close and
turn on the pulse timer circuit. To test, remove the current switch from the unit.
Using an ohm meter on Rx1 scale, check to see that the switch is open,
indicating no continuity. Using a common magnet, move it to within one to
one-half inch from the current switch while watching the ohm meter. As the
magnet nears the current switch, it should close, and continuity should be read
on the meter.
6.2 TESTING THE PC BOARD
An oscilloscope is required to test the PC board. Set the oscilloscope sec-
ond/div to 2 ms and the volts/div to 5V. Place the negative lead on pin 7 of the
transformer and the positive lead to connector J2 pin 3. The current switch
must be closed so jumper between pins 1 and 2 on the J4 connector, or place
a magnet next to the current switch, if you know it works correctly. Turn the
Pulse+ on. A square wave should appear on the oscilloscope. The “on” and
“off” time controls should vary the wave form on the oscilloscope. A bad
thermostat will also prevent the PC board from operating.
6.3 TESTING THE THERMOSTAT
The thermostat is located on the back of the heat sink and is connected to J5.
It is normally closed and, if the fan malfunctions or if the duty cycle is ex-
ceeded, the thermostat will open at 180 degrees F and shut down the unit. To
test, use an ohm meter to check for continuity across the thermostat leads.
6.4 TESTING CR1 AND R1
CR1 is the main diode coming off the + input and mounts to the heat sink. R1
is the power resistor inside the heat sink. If either is open, the Pulse+ will not
operate. To test, place an ohm meter on DC+ in the Rx1 scale. Attach the
positive lead to the + input and the negative lead to the + output. The meter
should read from 4 to 5 ohms. If open, check CR1 and R1 separately.
NOTE: The following conditions were used through-out the above test.
WELDING GAS: Aluminum (Argon), Steel & Stainless (98% Argon -
2% Oxygen)
POWER SUPPLY: Flat Slope C.V.
WELD POSITION: Flat
WELD TYPE: Fillet