Now I know why that welder is so crappy… AC??
Thanks for the run down. I may do this to mine at some point…
Also, I wouldn’t count the cost of the long cord with the welder. I bought a 12ga x 25’ extension cord from HF for $20, and have used it for lots of other stuff too. 10ga is overkill for that welder. So your actual conversion cost was closer to $50, not bad!
I didn’t take many pictures of the conversion process. When I open it up again to arrange the resistor circuits I will take more photos. Here is where I put my capacitor:
Here it doesn’t block the air flow through the welder. Capacitors don’t need to be air cooled. And it tucks right in under the circuit board and between two of the rubber foot screws. I used JB Weld to hold it secure and keep it from rubbing on the screws.My Harbor Freight welder failed on me yesterday for the very first time. Armed with intimate knowledge of the inner workings of my unit, I did not automatically junk it and go buy another like others. Instead, I opened it up and determined the problem.
The welder was welding particularly cold, and I saw smoke coming from the torch handle. Eventually it failed to arc at all when I pulled the trigger; it only fed the wire. So I touched the wire to the ground clamp and pulled the trigger. Only wire. Then I opened the case, released the wire feed roller, and touched the wire to the positive pole on the capacitor. Trigger pull; no arc. I took a multimeter, set it to Volts DC and tested the poles of the capacitor. It charged up to 30 some volts, so I knew the innards of the welder were working fine, and that there was a fault between the capacitor and the torch tip on the negative side. I opened up the torch and saw smoke residue inside, and where the lead was supposed to be electrically connected to the brass torch tip there was a lot of nasty looking stuff. I pulled at the lead and saw where it was supposed to be threaded, and immediately knew that thar was the problem. So I sanded the surfaces and soldered the connection together, assembled the torch back together, and proceeded to continue welding on my merry way. No cost repair. Powerful knowledge.
Good news Brian .
Thanks for sharing 
Here is an example of my welder on DCEN with the two resistors across the capacitor. The wire is Hobart E71T-11. For this weld I had perfectly prepared work that was bare clean bare metal. The pipe is galvanized. I had virtually no spatter, but two tiny bbs welding these two puffer pipes.
I was wondering where you found the parts. I looked on eBay but wasn’t sure which parts were correct. Do you have a link?
150 amp three phase bridge rectifier: It seems the design has changed. This is the link to what they sell now:
Capacitor: whatever you can find. Used will work. Look for a 50 volt 50,000 microfarad or better. Or you can get several 2.7 volt or other small capacitors and wire them in series. Here’s one
http://www.ebay.com/itm/Sprague-Powerlytic-36DE-Capacitor-25000-uF-microfarad-50-volts-DC-50VDC-NOS-Cap-/301541243284?pt=LH_DefaultDomain_0&hash=item4635423994
It’s a little small, but you could get a few cheap 10,000 microfarad capacitor and wire them in parallel:
http://www.ebay.com/itm/20pc-Rubycon-50V-10000UF-Electrolytic-Capacitor-105-C-30X41mm-NEW-/361243309414?pt=LH_DefaultDomain_0&hash=item541bc77566
These are cheap, but this particular lot has many. You should be able to find them in smaller quantities.
And for the inductor, I used bare 4 AWG copper wire and used vinyl electrical tape around it lengthwise for an insulator. The toroid core I bought:
http://www.ebay.com/itm/310839060200?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
i’m afraid that 150 amps rectifier is half wave, not full and your loosing half of the dc cycles. those 100 amps full wave work just fine, they have around 10-25% tolerance anyway.
If that were true, and since energy is neither created nor destroyed, then where is the power going? I am not afraid I’m losing half the DC cycles, since my welder is hotter on DC than on AC.
Would it just cycle back into the grid without any real draw, like a tv that’s turned off?
What is the difference between full wave and half wave ,is it the way the diodes are wired, not enough diodes, or just the type of diode,?
I dig it. I am so going to do this. It is too easy you almost have to if you have a HF flux core welder.
Hello Leroy,good luck with your mig welder mod, it should work good for the thinner metals like the barrow housing and the like. I am not sure of your knowege, be carefull with dc voltage,if it rises higher than expected could be real dangerous comeing off the caps,as DC voltage hangs on and dont let go,unlike ac that is safer, my mig welder has 6 caps,and a contious bleed resistor acrrost the caps at all times, so it pulls the high voltage down too safe level, directly after the caps serve there voltage stabilizing purpose.I had some 220 caps on my hho torch, and when i tested the caps for power,it sounded like a 22 pistol pop,zap, jolt, just glad i wasent the ground.The mig welder voltage should be under 30-40 open circuit voltage,much less dangerous, other than the caps.Let us know how it helps, i have a HF that may get the boost sometime.A bigger power fan will add more duty cycle too.
Thanks for the input on the capacitors. I don’t dig into much without first consulting some of my friends who know better than I. My first bad experience was when I was 15 and I dug the capacitor out of a furnace fan. It got me but not too bad. Just enough to let me know what a capacitor does.
Thats about the way i am when it comes to electric or electronics, I caint remember how i tested the cap. i think i unpluged the water torch, and hung a srewdriver with plastic handle close too the other leg when it scared the out of me. shortly after that i pulled the cap out of the circuit for model changes,and never put it back with the water torch, after testing the torch on my geo metro,it took about 8000 watts too idle the car, it was too much drag on an alternator, Any way i switched too wood gas about a year and half ago when i bought the Wayne Keith plans booklet.I did get a hell of a zap trying too make the trigger circuit work on a home made plasma cutter, that one dident make it much past my arm, though it did heat it up a bit.I am glad i bought a plasma cutter now.
Well, I looked up what a half-wave rectifier is, and sure enough, it exists. But the thing is, that the three-phase rectifier takes the sine-wave single phase AC and converts it properly into a bouncy DC signal. So there is no need for a full-wave rectifier, thank you very much.
Hi Brian Woodrow,have you welded with the three phase diode yet and or how good do they work, i was thinking on using them for replacements for my HF mig too, are you mounting them too the original heat sink plates,or adding different heat sinks.Happy Easter
Hey Kevin. I have welded a lot with my welder since I made this mod last year in February. So it’s been over a year. I haven’t opened it up to change the resistors, yet, but I can open it up and take some photos if you’d like.n The three phase diode works fine with a single phase. I think it’s a bit hotter because the signal is steady and on all the time instead of on/off/on/off/on/off. Just my opinion.
I went and bought a snap on welder that is actually made by mostly century parts, it has 6 caps with one big resistor accrost all of them on the bus bar,so i am good on the pics, good too know them diodes like you used work good.THANKS
I have been aware of these modifications for the little HF welder but never tried them.
Yes the welds are ugly but I just thought this was because I sucked lol.
Maybe I try this then?
I have some big Diodes from an old Exide battery chargers and some oil caps kicking around.
I noticed better wire helped.
These are the kind I have, as you can see you you need a heat sink to use these ( sold separately )
http://www.ebay.com/itm/4-NOS-1N4045-DIODES-100-Volt-275-Amp-Make-full-wave-Welding-Rectifier-/111951827161?hash=item1a10d950d9:g:TwwAAOSwdU1W-tII
Add this project to the growing list
I always come back to the old stuff.
This guy is one of the most dangerous and amusing people on Youtube.
Fins blowing up watermelons also never gets old.
Be careful out there.
