IGBT cheap welding machine mods

[simce]

Hi,

I've recently purchased a super cheap, most likely Russian IGBT based welding inverter named "Уралмаш Inverter MMA-300" that should be capable of delivering 300A, but the setting knob and value on display does not seem to be real (measured current with clamp shows significantly lower current than set value). Regardless of the fake specification that it can deliver 300A, i'd like to modify it to show real values on display so i'm sure i'm welding with proper currents, as much as possible with this type of device.

The board inside is marked to be: R-ZX7-100D-BQZKB-2

I'm wondering if there's anyone that might have a schematics of this device so i can analyze it and make a proper calibration?

Thanks,
Blagoj

 

[BradtheRad]

For the time being it's wiser to avoid modifying anything inside.

My style is to cut paper to fit around the dial, and tape it to cover the numbers. Then write new numbers to match my own measurements.
Or perhaps label positions that suit certain sizes of welding rods, or thickness of pieces being welded.

Later you can modify the insides, as you gain a sense of its workings.

 

[simce]

Thanks for the reply which is valuable when i'll get a sense about the used materials.
However, since my engineering mindset pushes me to have right numbers which correspond with the actual current flowing for the sake of clarity, calibration will be the way forward. Knowing the right numbers will help better understand the situation.

 

[BradtheRad]

Are you talking about a meter reading Amperes? Then a simple traditional arrangement is a shunt resistance across the meter. By increasing the resistance, it causes higher meter readings. To avoid burning the meter it always must have a shunt solidly connected, to carry heavy current.

Or, there are other methods to detect Ampere level, such as Hall device, or wire coil, etc. If you can locate the circuitry which does that, you may find an easy adjustment via potentiometer.

 

[simce]

This is display which exposes information on current that will be generated when welding starts.

The measurement is done by a feedback towards the control electronics taken from shunt resistor. So, the display shows preset current that should be maintained, and the control logic compares the preset value with the measured value. It should not be a complex circuitry, but before i jump into analysis of the PCB i was wondering if anyone has schematics so i can ease my life.

 

[RonnieB]

Hello, this is off topic but not sure exactly where to post but anyway got a SnapOn MM140SL mig/tig welder & just wondering if a foot pedal can be added or tied in somewhere where i can have control of the amps while tigging aluminum. I've heard & been told yes but none that knows how but was recommended to post on this sight as the one that said post here said it's very possible someone would know how or has done it. Since it has a rotary type switch as seen in the pics, is it just tie a potentiometer inline with the tig setting wire i'd use the most & have it mounted in a foot switch which i already have a regular foot pedal that"s just for on/off operation or is it more to it than that. Any drawing of wiring or any info would be helpful whether its possible or not. Thanks.

 

[alexjeffery007]

Hello, this is off topic but not sure exactly where to post but anyway got a SnapOn MM140SL mig/tig welder & just wondering if a foot pedal can be added or tied in somewhere where i can have control of the amps while tigging aluminum. I've heard & been told yes but none that knows how but was recommended to post on this sight as the one that said post here said it's very possible someone would know how or has done it. Since it has a rotary type switch as seen in the pics, is it just tie a potentiometer inline with the tig setting wire i'd use the most & have it mounted in a foot switch which i already have a regular foot pedal that"s just for on/off operation or is it more to it than that. Any drawing of wiring or any info would be helpful whether its possible or not. Thanks.

Hi, IGBT technology is being used in many tig/mig welders. you can visit amazon related to your type of welder and ask the vendor for documentation may be it will help also your question is very strange.
https://www.amazon.com/EVERLAST-PowerARC-160STH-160amp-Voltage/dp/B00H2VETB6.