Lincoln Electric POWER FEED SVM185-A - Manual (Page 71)

THEORY OF OPERATION E-3 E-3
POWER FEED® 25M
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POWER FEED® 25M
The POWER FEED® 25M is a two roll, high perfor-
mance, digitally controlled, modular wire feeder that
operates on 40 VDC input power. It is designed to be
a part of a modular, multi-process welding system.
Refer to Figure E.2.
Network communications, intelligence, PC board input
power, and arc voltage feedback is received and
transmitted through the input network receptacle.
The feed head drive control board processes the
information it receives from the various user operated
switches such as the gun trigger, 2-step/4-step, and
cold inch switches and sends this information to other
system components. This information is evaluated
and the correct commands are transmitted to the feed
head drive. The feed head drive control board then
sends the signals to energize the active components
such as the solenoid and wire drive motor. The tach
feedback signal is processed on the feedhead board
which regulates the motor armature voltage so as to
maintain the required wire feed speed.
FIGURE E.3 - GAS SOLENOID CONTROLS
When the gun trigger is pulled, the voltage sense
board relays the electrode sense signal to the input
network receptacle for processing by the power
source.
The STATUS LED is designed to blink a red and
green code if a fault should occur.
There is one DIP switch bank located on the wire
feedhead drive board. It is labeled S1 and is used to
set gear ratios and arc polarity.
GAS SOLENOID
The gas solenoid permits the POWER FEED® 25M to
be used for gas metal arc welding (GMAW) processes.
When the gun trigger circuit is activated, the control
board signals the solenoid to activate, which allows
sheilding gas to flow through the gun to the arc.
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
VOLTAGE
SENSE
LEAD #67A LEAD #67
PUSH PULL
DAUGHTER
DRIVE
MOTOR
GEAR BOX
AND
CONDUCTOR
BLOCK
FEEDBACK
TACH
STATUS LED
GUN TIGGER AND
DUAL PROCEDURE
RECEPTACLE
2-STEP/
4-STEP
CONTROL BOARD
FEEDHEAD
DIP SWITCHES
TO POWER
SOURCE
INPUT
NETWORK
RECEPTACLE
HEATER LIGHT
CONNECTOR
FOOT AMPTROL
COLD
INCH/
GAS
PURGE
GAS
SOLENOID