Bimson 200 amp Inverter MIG

Richiew · Feb 19, 2026

Not quite there yet. The welder was reassembled Tuesday and I got round to testing this evening.

I appear to have adjusted the MMA amps wrong. Thought there was something up when I had trouble starting up a rod at 125 indicated amps.

Wacked up the amps and obtained these figures.

Indicated ≈ Actual
159 120
169 125
187 140

The meter reading fluctuates obviously but I'm about 20 amps further out than before.

It's not too much better on the MIG side. The voltage looks correct at max volts. I'm seeing fluctuating figures from 23.3 up to 25 volts so the volts are all there. The max wire speed appears to have dropped. It now welds horribly globular at max volts and max wire speed, although there is sufficient wire speed further down the voltage range. It seems I will be getting the screwdrivers out again.

I did think about sending it back and that is still an option, however, I'm 100% sure there's a good welder in there somewhere and the vendor's just a box shifter. A replacement may be configured correctly but it's pot luck. The 32amp plug has arrived but it won’t get fitted until I'm sure it's not going back.

Richiew · Feb 21, 2026

After a lot of fiddling today. I'm sort of done with the welder. It's not set perfect, but it will have to do.

The MMA max pot was adjusted down so the display read 160 at maximum on the dial. This brought up the current on the clamp meter in line with the display at an indicated 125 amps. I should have tested over the range a little more but it seemed ok and sparked up easily, plus I wanted to get onto the MIG settings. This adjustment might appear to have lost me some top end but I never use more than a 3.2mm electrode anyway. I also think that the welder may have been overspecced for MMA. Often the MMA max current quoted on a welder is lower than the corresponding TIG or MIG current, see the latest R Tech inverter MIG specs as an example.

I think I made a mistaken assumption in my previous post. The welder appeared to run out of wire speed at high voltages. Thing is the welder was running at 23 to 24 volts and short circuit MIG on 0.8 wire tops out at around 22V according to one source I've read. There's a 1mm wire roller groove on the machine for a reason. I think I was looking at numbers rather than how the machine welds. I did a lot of fruitless adjusting until I realised. I might be talking rubbish but this is how it seems to work with this welder. I'm just trying to make sense of it.

The top end voltage on the MIG setting is fairly accurate. I think it's running slightly hotter than the display voltage. The voltage has greater range than the specs suggest. If the dial is set at the bottom, the voltage is really low (Readings around 12 or 13V?) and the display doesn't change even though the dial is turned and the measured voltage does increase. This is assuming my meters are accurate. Despite the display, it's really going to be another old fashioned MIG, setting by ear and testing on scraps before committing.

Some test welds. 6mm plate. From memory, I think the display was 22V and the multimeter read a little higher, 22.5V.

It would be interesting to get a 1mm spool of wire on there, it should require less wire speed.

Different angle, same weld.

There was a lot of high-powered testing today and the 13amp fuse hadn't popped.

Fuse in question.

Random replacement fuse pulled out of spares drawer.

Narrower gauge and much softer too. For accuracy, I had to re-measure away from the squashed bit.

13amp plug chopped off and 32 amp going on.

Richiew · Feb 21, 2026

Interestingly, I twiddled the trimpot for MMA voltage by mistake. MMA voltage seems to be the only function that the welder appears to actively measure on the displays. I got it up to 85 volts before I knocked it back down. I wonder if I could get it to run a 6010 electrode? Possibly wouldn't do the machine much good?

Richiew · Feb 21, 2026

Knowing what I know now. If I was starting again from scratch I wouldn't have touched a thing after checking with the meters and just used the correct measured figures as a baseline for settings.

J.F · 2026-03-14T22:38:39+0000

Richiew said:
After a lot of fiddling today. I'm sort of done with the welder. It's not set perfect, but it will have to do.

The MMA max pot was adjusted down so the display read 160 at maximum on the dial. This brought up the current on the clamp meter in line with the display at an indicated 125 amps. I should have tested over the range a little more but it seemed ok and sparked up easily, plus I wanted to get onto the MIG settings. This adjustment might appear to have lost me some top end but I never use more than a 3.2mm electrode anyway. I also think that the welder may have been overspecced for MMA. Often the MMA max current quoted on a welder is lower than the corresponding TIG or MIG current, see the latest R Tech inverter MIG specs as an example.

I think I made a mistaken assumption in my previous post. The welder appeared to run out of wire speed at high voltages. Thing is the welder was running at 23 to 24 volts and short circuit MIG on 0.8 wire tops out at around 22V according to one source I've read. There's a 1mm wire roller groove on the machine for a reason. I think I was looking at numbers rather than how the machine welds. I did a lot of fruitless adjusting until I realised. I might be talking rubbish but this is how it seems to work with this welder. I'm just trying to make sense of it.

The top end voltage on the MIG setting is fairly accurate. I think it's running slightly hotter than the display voltage. The voltage has greater range than the specs suggest. If the dial is set at the bottom, the voltage is really low (Readings around 12 or 13V?) and the display doesn't change even though the dial is turned and the measured voltage does increase. This is assuming my meters are accurate. Despite the display, it's really going to be another old fashioned MIG, setting by ear and testing on scraps before committing.

Some test welds. 6mm plate. From memory, I think the display was 22V and the multimeter read a little higher, 22.5V.

It would be interesting to get a 1mm spool of wire on there, it should require less wire speed.

View attachment 530883

Different angle, same weld.

View attachment 530885

There was a lot of high-powered testing today and the 13amp fuse hadn't popped.

Fuse in question.
View attachment 530886

View attachment 530887

View attachment 530888

View attachment 530889

Random replacement fuse pulled out of spares drawer.

View attachment 530890

View attachment 530891

View attachment 530892

Narrower gauge and much softer too. For accuracy, I had to re-measure away from the squashed bit.

View attachment 530893

13amp plug chopped off and 32 amp going on.

Just out of interest what size was the cable going into the moulded plug in mm2, because I'd be surprised if it's the correct size to take 32A.
Most likely 1.5mm2 3 core so max 16A plug. Just a thought because last thing you need is the cable to the welder melting.