Fixing a MIG Welder [Rectifier Replacement]

today we're working on a fire power MIG welder it's the F p90 model basically what happened is there was a power surge and this thing was plugged in when I turned it on it started smoking snow really bad and then pretty much lost all of its power to penetrate metal so we're going to open it up and fix it today so you've got these three Phillips head screws okay so this is the choke the choke in this case is a big inductor wrapped around an iron core that's used to filter out AC currents this is the transformer the transformer is two coils of wire around an iron core and it's used to transform the 110 AC from the wall outlet into 30 volts ac what a suspect this happened is the diodes burnt out it looks like the diode bridges are up heat up here somewhere so we're going to keep disassembling the diode bridge I'm referring to or rectifier uses a set of diodes to transform the output of the transformer which is 30 volts ac to a DC current that's used to weld yeah it's like I've got four one two three four five six seven eight nine Phillips head screw okay so this is our diode bridge we're going to go in here and we see that these connections have sort of come off and this one kind of looks all burnt up sees kind of messed up there oh so we're going to replace this diode bridge okay just so we can test the transformer transformer output two right here and right here so it should be outputting about thirty volts AC we're going to switch to voltage AC going to plug this in turn it on we're going to measure voltage here here and we get 31 volts AC so transformer is working correctly it's going to give you guys a better shot of that like measured transformer about 31 volts AC okay so that tells us that the the power to the rectifier bridge is correct and that the problem must be the rectifier bridge so that's further evidence that this needs to be replaced so again if we looked at this wiring diagram this right here is the rectifier braid that the four diodes and this right here is the transformer so the transformer has an input here and here to the rectifier bridge and powers this bridge and then the bridge then therefore outputs DC to the ground clamp and the torch so knowing that the power is good at these two connections right here tells us that everything before it is good so that means that once again that the rectifier bridge is faulty okay so this rectifier has a bolt that goes through here and has it not attached on this side so it's a 13 millimeter nut so we're going to take that off next we have this connection right here with this lock washer on it this is a 10 millimeter and then we're just going to put this back on like this so we don't lose it next we have this connection right here for the wire motor just pull off this just pulls off like that alright next we have these two screws holding this on take that off the Phillips head now get in there huh sound they're pretty tight let's try this one that came off got do it the old-fashioned way to this bottom one there we go that one was in there tight this off okay the only thing left holding the sign is the two connections from the transformer if I were to do this again I would take that first nut off do that last alright so don't lose your washer here now we have one down here put the nut the washer and the bolt up forgot one up here forgot this guy up here okay now we can just remove the rectifier okay we got our new rectifier we're going to put it in attach the nut on the back there we go okay we're going to reattach this alright next we have the connection for the torch the negative plate okay now we have this connection that comes from the choke and ultimately goes to the ground clamp that goes to the plus plate okay now we need to hook up the two lines from the transformer this one was in a slightly different spot so I had to move the wire okay this is the thermal shut off on the old one and one here but it looks like in this new part the two holes are supposed to go in or up here so we got to move this I'm going to cut this zip tie and see if I can move it up here all right um can't really fit the other one in there but that's on secure I think that'll be okay okay so I put all the covers back on just a couple screws now some test it out seems to be working to me not the best well there so go easy on me but it's working thanks for watching

Channel: MattsMotorz

Views: 65,311

Rating: 4.6973686 out of 5

Keywords: DIY, do it yourself, repair, fix, mechanic, auto, automotive, How to, MIG welder repair, replacing a rectifier, replacing a diode bridge, welder wont work, how to fix a welder, welder smoking, welder will not penetrate

Id: 5OZOjkaJzKQ

Length: 9min 22sec (562 seconds)

Published: Sat Jun 14 2014