www.esabna.com
DATE: May 6, 2003 BULLETIN NO:M_03_010
TITLE/ PRODUCT NAME: MigMaster 250 Plus Cap Discharge Resistor
RATING:
_
(Action is Required) (Potential Problem)
_ DIRECTIVE _ _ ALERT
_
(Action is Optional) (Enhanced Product)
_
(Unrestricted) (Restricted Distribution)
PRODUCT SERIES/ MODEL:
MigMaster 250 Plus
SERIAL NO:
Serial number prior to - MxxJ0319XXX
SUMMARY:
The MigMaster 250 Plus is designed to balance a low cost Mig power source with optimum arc
stability and welding performance. To accomplish this balance, capacitors are used to help smooth and
stabilize the DC output power. These capacitors charge up during welding and discharge after welding
stops. A bleed down resistor is used to quickly bleed the capacitor voltage.
Some MigMaster 250 Plus power sources can experience wire “sparking” when the electrode
wire comes in contact with the workpiece or any metal object connected to the work lead shortly after a
weld is finished. The degree of “sparking” is a function of the voltage charge remaining on the internal
power source capacitors and the time between turning off the arc and touching the electrode to ground
potential.
If the discharge time for your MigMaster 250 Plus is too long and you want to reduce the
“sparking” tendency, a resistor change is required. Follow the instruction that follow
X_ INFORMATION _X_ PRODUCT IMPROVEMENT
X_ General Distribution _ _ Business Confidential
OPERATIONAL IMPACT:
Wire “sparking” will be significantly reduced without affecting any other power source welding
characteristics
ACTION:
Replace the R3 resistor (50 ohm 100W P/N – 99512178) with a 25 ohm 100W resistor (P/N –
17280025) in order to discharge the capacitor bank quicker:
1. Remove the power source lower left side panel
2. Locate the R3 resistor and disconnect the resistor from the wiring harness.
3. Remove the resistor from the power source base and save the sheet metal mounting screws
Resistor R3
4. Drill two 1/8” diameter holes in the base at the “New Hole” locations shown below.
5. Mount new resistor, reconnect harness and replace side panel
CONTACT:
ESAB Welding & Cutting Products
Product & Service Information Group
843-664-4416 Phone
843-664-5539 FAX
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