Arc Machines 227 - Manual (Page 73)

MODEL 227
OPERATION MANUAL
Doc # 740063 Rev E
SECTION VII - CALIBRATION
7.2
CURRENT CALIBRATION Cont.
3. The test points and adjustments for Current Calibration are located on the Center
Plate under the computer cover (front panel housing). Turn the Power Off and
unscrew the two computer cover retaining screws in the front. Lift up on the
cover and expose the center plate. Prop the cover up so it will not fall but so you
can still operate the system
Locate test points REF. TP. and CUR. TP. Locate Adjustment screw labeled
“Current Gain”. Turn Power back on.
4. If an External Shunt is to be used connect it between the Work (ground) connector
on the Power Supply and the Work (ground) connector of the Weld Head Adapter
Cable or manual torch. Current is always measured along the ground return path.
5. Insure everything is ready to strike an arc. Turn M-227 power ON. The system
should return to your calibration weld procedure. Set the Weld/Test Mode to
WELD.
6. Set up the DMM to read on the 200 mv DC scale if you are using the external
shunt. Set it up to read on the 20 VDC scale if you are using the center plate test
points.
7. If you are using the external shunt prepare to insert them into the red and black
test point on the shunt.
8. If you are using the center plate test points prepare to insert them into REF. TP.
(black lead) and CUR. TP. (red).
9. DO NOT INSERT THE PROBES UNTIL AFTER THE ARC IS STRUCK. The
high frequency start may damage some meters.
10. Press the SEQ START key.
11. As soon as the arc is struck (after prepurge) insert the Probes into the center plate
test points or into the external shunt if it is being used.
12. During Weld Sequence Odd Levels the DMM should read as follows:
Center Plate Test Points = 2.00 VDC +/- 0.01 VDC.
(1.99 VDC to 2.01 VDC)
AMI External Shunt = 100 mv DC +/- 0.25 mv DC
( 99.75 mv to 100.25 mv )
If out of tolerance adjust the “Current Gain” trim potentiometer adjusting screw
on the Center Plate.
7.3