Notes: only attempt to repair this machine if you have knowledge and understanding of electronic components and the
dangers of electricity and components holding a charge of high voltage electricity. Before maintenance contact us for
authorization is suggested
.
DO NOT REPAIR OR MODIFY MACHINE IF STILL UNDER WARRANTY
If the machine fails to work after maintenance and checks, please contact your local distributor or our after-
sale service center.
MIG 250M EXPLOSION DIAGRAM
WARNING!
Experimentation and careless maintenance may lead to more
problems to the machine. This will make formal diagnostic and repair more difficult.
When the machine is open there may be exposed connections containing life-
threatening voltages. Any direct or indirect touch will cause electric shock, and
severe electric shock will lead to death.
Faults
Remedy
Porosity in the
weld
The cause of porosity is from oxygen (air) or gasses contaminating the weld (MIG or TIG). To
prevent this check the following:
1) Make sure the valve of cylinder is opened and has enough pressure.
2) Check if the flow meter is opened and has enough flow .User can choose different flow
rates according to welding current in order to save gas .But too little gas flow may cause
porosity because not enough shielding gas is covering the welding spot. We suggest that
flow rate must be kept minimum 10L/min.
3) Check if torch or gas hose is not blocked, damaged, pinched, melted or has any holes.
4) The welding material might be contaminated with oil or dirt.
5) Strong wind will lower the welding quality.
Power indicator is
not lit, fan does
not work and no
welding output
1. Make sure power switch is working.
2. Check connections from ON switch to power board are in good condition, check continuity
of ON OFF switch.
3. Check if the plug point you are using is working.
4. Check if supply voltage is correct
5. Auxiliary power board might be faulty.
6. Control board might be faulty.
Power indicator is
lit, fan works, no
welding output
1. Check if all cables are connected properly.(Earth cable in correct quick connector)
2. Check if correct mode or function is selected.
3. Output connector is disconnected or damaged.
4. Control circuit might be faulty.
QC (Quality
Control) indicator
is on permanently
1. Can be in overheat protection; wait for 15 minutes.
2. Maybe it is overcurrent protection, turn machine off for 30 seconds then switch on again. If
still not working there is a fault on the MOS board.
3. Mosphets on control board might be faulty.
4. Fast recovery diodes or transformer might be faulty.
Output Current is
not stabilized
1. Supply voltage is not stable.
2. Potentiometer might be damaged?
3. There is harmful interference from supply voltage or other equipment?
4. Bad connections - Hot/bad connections or points on earth cable, electrode holder & torches
can cause current to drop or be unstable.
