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21st December 2023, 09:50 PM #1Most Valued Member
- Join Date
- Aug 2015
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- 4,434
Problems with UNIMIG Workshop 255
Factory neighbour brings me his welder. Says it keeps stopping.
I take the covers off, blow the dust out, inspect the capacitors and glance at the control board. Both seem OK.
• Power it up, try some test welds. It keeps popping – not a continuous weld – and burning back up the wire:
IMG_0057.jpg
I try the burn-back setting on the front panel. Seems to have no impact.
• Turn the feed up to 10. A little better, but just building up on the surface, and still popping.
Like the welder is only intermittently shunting current, like twice a second. No penetration.
Only way I got a decent weld was to also turn the power up to the max (3 on the coarse switch, 4,5,6,7 on the fine).
Unless I am careful, the flame front seems to vaporise the wire before it can get to the work.
Less than 2,5 on the switches just pushed glowing red wire into the job. No real arc/flame front:
IMG_0058.jpg
I have spent 2 or 3 hours, and half of that is un-clogging the tip
(where the burn-back has plugged it with a huge blob of iron perfectly bonded to the copper!)
Now, this is an old welder. It has probably been used to death, and isn't worth fixing.
So, I roll up the cables, and get ready to wheel it back to him.
Start to think about what could be failing.
Does the circuit board have dirty potentiometers?
Is it somehow using "Interval mode" on the lower power settings?
This thing can probably still be repaired. It looks very similar to a current model
(the UNIMIG workshop 270).
I'm at a fork in the road. Not sure if it is scrap metal.
P.S. While fiddling with all the settings, I notice the VOLT/AMP meter is black.
First impression is that it is broken, but a later look in an online manual says they are an option???
P.P.S. There are two outputs on the front. Not documented in the manual.
Wonder if output 2 would make any difference.
Attached Images
- IMG_0058.jpg (262.4 KB)
- IMG_0057.jpg (208.4 KB)
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