I came across a tig welder (miller maxstar 175) for $100 locally. The reason for such a low pricing is because its a 3-phase system, where as most homes run a 1-phase system.
I've been searching online for a bit now and can across the ability to convert the 3-phase maxstar to the 1-phase maxstar 152. Just wondering if anyone has any info on this...

 

For those of you interested I found some stuff on it, here's a direct copy from hobartwelders.com, user Brasco

maxstar 175 converted to maxstar 152
________________________________________
Picked up a maxstar 175 inverter welder for a song because it is 3 phase only and unlike
a powcon there are no jumpers to change over to single phase.

Found out the maxstar 152 is the 240 volt single phase version of the maxstar 175 460 volt 3 phase welder. Looking over the schematic I found that they wind the control board transformer on the cooling fan core. They list the fan as 230/460 volt. I cut the jumper on PLG11 term 2 and 3 cut the wire from PLG11 term 4 and soldered it to PLG11 term 2. This converted the fan to 230 VAC .

The 230 VAC now is connected to L1 and L3 , L2 is left open. I used L3 because I would'nt need to cut as many wires this way.

The maxstar 175 control board has a jumper (#47) from RC2-4 and RC2-6 . The maxstar 152 (#47) jumper is on RC2-3 and RC2-6. I had to cut the plastic on the molex connector to get the pin out, but it slid right in the RC2-3 spot. I powered the welder up and have 45 VDC OCV (max is 95 VDC)

Put some external meters on and was able to pull 50amps A 25 VDC SMAW setting before I stuck the rod, then 200 amps @ zero volts.

Tried GTAW and had no problem 100 amps 15-20 VDC . All conrols work fine . Using lift Arc and finger tip control. The SMAW works, I just need to get better at stick welding.

 

Here's the schematic, The red rectangles just identify where the modification is being done

 

Well I decided to buy it, i figure why not for $100 it came with all accessories necessary so if the conversion doesn't work I can either part it out or save for another tig welder.

Also started on the conversion, pretty simple, had a little trouble figuring out where PLG11 but found it. Here's what I did in pictures...

Here's what I get for $100






Glad it came with a pedal, didn't realize how expensive they are, this is the sole reason why I bought it


Here's what the board looks like


I first started with the RC2-4, RC2-6 jumper, just removed the pin of RC2-4 to the RC2-3 position, on the board it will show where RC2-3, RC2-4, and RC2-6 is


Removing the pin


Putting it in position RC2-3


Now for PLG 11, Its on the other side of the welder, (note that the colors on the female connector match up with the electrical diagram)


Here you can see that Term 2 (blue) and 3 (gray) are jumped on the male connector, and the wire is labeled 7, just like it is in the wiring diagram
Now you want to chop the jumper on the male connector, as you notice it does coordinates with the two colors on the female connector (there's only one jumper so its pretty obvious which one to snip )


Now you want to connect term 2 to term 4 (color is white, shown on the female connector)


Term 4 on the male connector


Here's term 4 connect to term 2


Now all i need to do is get a 240V plug and hook up L1 and L3* but i wont be able to do it till i go to my parents where they have a 240v outlet.

I'll keep you guys updated

 

sorry for the late update, but anyways... I redid the 460v plug to the 240v plug using L1 and L3, hooked up the ground which is green, and turned on the the machine and everything powered up.

Now I haven't touched a tig welder in about 4yrs so I took a look at the manual and had the settings at GTAW and had the cables setup as DCEP (the ground cable to the neg and torch to the pos). The pure argon was set at 10psi and the pedal was ready as well, I tried to make a puddle but i kept getting it too hot or something and the tungsten just melted like I were in SMAW mode. I'm sure I'm not doing something right, I'll try to work on it again sometime this week when I get a chance to go home. I'll keep you guys updated and try to get some pics

 

thanks for posting this information

 

Shouldn't it be setup for DCEN for welding? I'm assuming you're just using a piece of scrap steel...

 

you're right boostcreep, it should be on DCEN (torch connected to neg and the ground cable to pos)

I tryed a few passes of pushing a puddle with mild steel and then tried adding a little filler rod... the welds don't look that great b/c I'm still a noob to tig welding, but the machine is absolutly flawless! The greatest $100 investment I've ever done!


here's trying to push a puddle, I know it looks pretty bad..


Tried it with some filler rod...


heres another with filler, I was pushing it too fast, then too slow... and didn't add enough filler

 

thats awesome man^

 

Glad you got it figured out!

 

I am pretty impressed with the phase changeover. Nice work.

 

That is a heck of a deal. I would be all over one if I could get it for that kind of price.

 

I appreciate your conversion ideas as I have located a 175 as well. How is it running? Got any serious time on it yet? I found another post about converting the unit and this is what someone said:

"The MaxStar 152 / 175 are built with easy to get genaric Intergated Circuits (CMOS)
It is basicaly a High Frequeny Switching Power supply. The Factory Schematics are easy to trace . The MaxStar 175 Can be converted to single phase use with output power reduction (about that of a maxstar 152). The Power FET modules would be the most expensive part to replace , and they usually explode and take the drivers with them."

and he goes on to say:

"The CMOS IC's are 4093 , 4023, 4013 4023, 40106,

The Linear IC'a are LF347N , LM7915 , LM7815 , LM311

There are 12 IC's total on the main board. The CMOS and Linear IC's are all very easy to come by. Digikey will have all of thease listed. They may even have the FET power modules. My maxstar 175 does not have the meter option. But I believe the 40 Pin IC for that would be a ICL7106 LCD 3 1/2 digit voltmeter IC. All of these are industry standard parts."

I am not sure what the poster thought the original conversion process was. Maybe it was similar to yours or maybe it is a different way to convert it over. I just don't want to buy one and fry it. Suggestions?

 

have you looked into a phase converter? the shop i used to work at used one on each 2 post lift. same story, got em cheap b/c they were 3phase and noone would buy them.

 

This conversion can be done without cutting any wires, just pulling pins and swapping their positions, works really slick using a flattened out pin (like for sewing) to release the tabs on the pins. Then the welder could easily be switched back to 3 phase if needed.

 

My house has 3 phase. I wish I could have got a deal like this. The old timers @ my local welding shop say the older Millers, are the best welders on the planet. Awesome tech right here! Most would have just bought a converter. Bravo!

 

I can follow this conversion until the last step. Instead of cutting term 2 wire and then cutting term 4 wire and connecting cut 4 (machine side) to the cut 2 (plug side?) could I just removed term 4 and insert it in term 2 position? Thanks.

 

I was able to borrow a tool for removing the Molex connector pins.



Close up of the tool

 

I came to the conclusion that the fan portion of the conversion could be done without cutting any wires.
Pulled the #7 jumper wire out of the #2 plug terminal spot of the plug and taped it. (will attach it securely to the harness later) Removed the terminal from the #4 spot of the plug and moved it to #2 spot on the plug. (That is a #2 scribbled on the plug) The same Molex tool was used to pull the pins.



Turned it on and it fires right up. Still waiting on some cable ends to attach my TIG torch and try it out.

 

Well not so fast. I am barely getting any current at full amperage. I double checked my wiring both for the conversion and for the 230v supply and couldn't find any problems. Back to my confusion. Am I supposed to tie the 4 terminal with the 2 terminal (plug11) or abandon the the 2 terminal as I did? Does the plug 11 only feed the fan or does it also feed the control board somewhere? Either that or something is fried. I can't find any components that have the magic smoke. Any help would be appreciated.

 

Update. The machine worked fine when converted back to 3 phase. Something is missing in this conversion write up that is not powering the board.

 

whats up with this photobucket BS?

 

Anyone have any detailed instructions for this conversation they would part with
thanks