Harbor Freight 90a Flux-core Ac To Dc Conversion

I just completed converting my HF 125 flux core to DCEN. It was not hard. Everything was a tight fit. I made all of the connections out of 3/16 soft copper tubing. I flattened the tubing and bent it to shape to make the connections from the rectifier to the capacitor. 3/16 tubing was the perfect fit on the wire so I made the lugs and crimped them onto the wire for the connections on the ground and the electrode to the capacitor. The picture isn't the best.

IMG_3613.JPG

Did a couple of before and after test beads and really can't tell much difference. But then I am not much of a welder. I have a lot of welding to do on the MG Midget that I am resurrecting. I'll have a better idea after I am done with that.
 
I did this conversion, too. Although a total noob when it comes to welding, I've already used the modded welder to repair a garden rake and wing-type weeder. The beads look pretty awful but the items are functional again.
 
I'm in the same boat. EBay purchases are easy. Finding time and the determination to geterdone is in short supply right now.
Bob Korves said:
I still have the parts I bought, but so far have not got around to doing the modification. Maybe the additional kick from danbbb will get me going on it...
Click to expand...
 
jonesn7 said:
I'm in the same boat. EBay purchases are easy. Finding time and the determination to geterdone is in short supply right now.
Click to expand...

Don't feel too bad. It took me over a year to get around to actually doing the mod. Once I got started it didn't take too long, though. The part that took the longest was figuring out the best path for the added wires. Being large-gauge they don't bend too easily & I didn't want to put too much stress on the diode and capacitor leads.

I did go to the extra trouble of attaching the diode bridge to a big heat sink. But it doesn't seem to warm up much at all during welding. In retrospect I probably could have just bolted it to the case. I did check to make sure the diode's exposed metal heat spreader was electrically isolated from the diodes.....
 
I may just have some heat sink material (aluminum plate). Maybe sandwich a piece between the case and diode. Plus some good heat sink compond.
 
The bridge rectifier that I purchased on Ebay came with a heat sink as part of the rectifier.
 
Well, I finished the mod last night at about 3am. This morning when I tested it out, I got one spark and then nothing. The fan and wire feed work alright, so I'm assuming the rectifier is blown. (I had a 120A.)

Now to troubleshoot the system. Good times!
 
My rectifier is 150 amps. I almost screwed up the connections. The diagram on the rectifier had the positive and negative reversed from the markings on the actual contacts/leads/pins whatever you call them coming out of the rectifier. I didn't notice the error until I was done making the connections when I noticed a "+" on the pin that the diagram indicated was a "-".
 
mickri said:
My rectifier is 150 amps. I almost screwed up the connections. The diagram on the rectifier had the positive and negative reversed from the markings on the actual contacts/leads/pins whatever you call them coming out of the rectifier. I didn't notice the error until I was done making the connections when I noticed a "+" on the pin that the diagram indicated was a "-".
Click to expand...

Looks like my rectifier is testing okay. The diodes aren't blown and they appear to have been labeled correctly...

If I'm testing my capacitor correctly, it also appears to be working. Wondering if I blew something within the welder itself?
 
One thing that I found is that the metal being welded had to have a really good ground connection and where I wanted to weld had to be bright and shiny. I also found that I had to have the wire pointing pretty much straight down if that makes sense. Too much of an angle and the wire would just feed out along the surface of the metal. I am not much of a welder. Have not done any welding in years. I am sure that my technique is awful at best.
 
You must log in or register to reply here.
Back
Top