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Hi and I just bought my first welder a couple days ago off CL, a used 115v Century Powermate 100 dual purpose mig. It appears to be in good condition. I got a heavy duty cart, cheap helmet, extra wire/tips and tank/gas with it. I didn't, however, test it to see if it actually worked but was told it did . I have never welded before but have been looking around on this forum and online videos to get some tips. The only spark I could create was about the size from a cigarette lighter flint and that was only a few times. Most of the time there is nothing, even when touching the wire to the ground clamp. I got a friend, who has a mig, to make sure I wasn't doing something wrong. He couldn't get an arc either. The welder powers on. Wire feeds and gas is emitted with a press of the trigger. It has solid wire and the polarity is wired correctly. I ran a new ground wire just to check and put a new tip on, but it still wouldn't work. I cleaned all the metal and tried several different pieces. What is most likely the problem/problems? I've read that these welders seldom have problems. Thanks in advance for your advice.
Reply:Polarity set correctly?
Reply:Sounds like a bad contactor. Not knowing the machine I can't tell you where to look. Possibly someone else is familiar with that unit or knows where you can get a parts diagram.Another thought would be a poor ground connection in the machine.
Reply:I'll get back to you later this evening. Do you have a volt meter and do you have the users manual?
Reply:Thanks for the replies guys.The polarity is set correctly according to the inside panel instructions.I checked the ground just inside the side panel door. Good connection there but have not taken the other panels off to check the wires inside.I do have a volt meter and would welcome further instructions on what to check. I did not get the user manual and have found very little info on the net about this welder. Thanks again.
Reply:I have the same results searching for information on that model, very lean pickings. But until we find a manual we can do some diagnosing.Ok, here is what we know.A] The unit powers on.B] Wire feeds.C] The gas valve operates.D] Part of the control board operates.E] No welding power.We may conclude the problem centers around the main contactor, power transformer, rectifier, capacitor bank, inductor and connecting wiring. Possible problem with the heat control and the related circuits on the control board.Lets start with the oblivious.With power disconnected from the wall, remove the covers and look for any loose or broken connections. Look for any components that may have burned out.Have you ever used the 50% trouble shooting rule? Probably not. You have a circuit, with parts; ABCDEF in that order.F is not working. Test point D. If D works, the problem is to the right.If D doesnt work, the problem is to the left. Keep cutting the circuit in half until you find the problem.Lets take the rectifier as the halfway point.The output of the power transformer [heavy copper wire] connects to the rectifier. There should be 3 wires coming from the transformer, one each connected to the diode assembly on the rectifier and a common connected to the heat sink of the rectifier. Open the pressure roll on the wire feeder, no need to feed wire now. It would be easer if your meter leads have clips to make connections.Set the voltmeter to the A-C scale at 200 volts. Connect one lead to the common point on the heat sink and one probe to the wire connection to one diode assembly. With the unit plugged in, power on, squeeze the trigger on the mig gun. You should see about 20-25 volts A-C. Next move the test lead from one diode assembly to the other and repeat the test. Again you should see about 20-25 volts A-C. Does changing the heat control have any effect?
Reply:transit,I checked all conections and could find no problems. There were a few connections that had mild oxidation around the connectors so I took them off and cleaned them. Tried the welder and no results. Also just wanted to add that this welder has two settings on the power switch, 90A and 100A. I had 4 white wires grouped, 4 black wires grouped running from the transformer to the circuit board. I tested them and then decided I didn't think those were the ones you were asking me to test. Anyway their voltage was 41.1v @ 90A and 45.1v @100A on each one- went down 0.1 with trigger and no change with heat selector.There is one large wire running from the transformer to the capacitor. There are 2 grouped wires from the transformer, one white running to the gun hose connector and the other is yellow and connects into a little round black connector on the circuit board. This also has another yellow wire running out of it. And lastly, 3 more wires running out the other side of the transformer- red, white and black all running to the power switch. Black wire carries 112.9v on 90A and 124v on 100A. Red wire had 124.5v on 90A and 136.7v on 100A. I'm pretty sure you weren't looking for any of this info, but I just didn't understand. However when I took the inside cover off, there is a wiring schematic glued to the inside. It won't come off so I can scan it, but maybe I can take a picture of it tomorrow. Thanks for the help and sorry for my electrical ignorance.
Reply:I checked all connections and could find no problems. There were a few connections that had mild oxidation around the connectors so I took them off and cleaned them. Tried the welder and no results. Also just wanted to add that this welder has two settings on the power switch, 90A and 100A.[ok you have hi-low power settings]I had 4 white wires grouped, 4 black wires grouped running from the transformer to the circuit board. I tested them and then decided I didn't think those were the ones you were asking me to test. Anyway their voltage was 41.1v @ 90A and 45.1v @100A on each one- went down 0.1 with trigger and no change with heat selector.[good you have A-C power from the transformer to the rectifier]There is one large wire running from the transformer to the capacitor. [ the capacitor, is it large about the size of a soda can? If so, there should be two wires going to it, one to the (+) terminal and one to the (-) terminal and a resistor connected across both terminals. The voltage should be about 58 and 63 volts D-C]There are 2 grouped wires from the transformer, one white running to the gun hose connector and the other is yellow and connects into a little round black connector on the circuit board. This also has another yellow wire running out of it. [these are the trigger connections to the control board]And lastly, 3 more wires running out the other side of the transformer- red, white and black all running to the power switch. Black wire carries 112.9v on 90A and 124v on 100A. Red wire had 124.5v on 90A and 136.7v on 100A. [these are the input power lines to the welding transformer, hi-low power]I'm pretty sure you weren't looking for any of this info, but I just didn't understand. However when I took the inside cover off, there is a wiring schematic glued to the inside. It won't come off so I can scan it, but maybe I can take a picture of it tomorrow. [a photo of the inside of the unit would be a big help. before posting the pic be sure it's clear]Thanks for the help and sorry for my electrical ignorance.Last edited by transit; 07-25-2009 at 04:00 AM.
Reply:I know this Miller manual is the wrong, but it dose have a wiring diagram that should be helpful. Go to page 33, figure 7-1 of the Adobe file, you will need to rotate the page clockwise and magnify the page to view it. Take note of the transformer in the upper right of the page [T-1]. The secondary of the transformer has three connections, x1, x2, x3. SR1 is the rectifier assembly, the arrow heads pointing to the right are the diodes assembly and C1 the capacitor, Z1 is the inductor. The instructions I gave you would have measured the A-C voltage from x2 to x1 and x2 to x3. That wire from the transformer to the capacitor that you mention is x2 to the bottom of C1.I think those A-C voltages are a little high and you may have measured the voltage from x1 to x3. If that is the case, the values from x2 to x1 and x3 should be half, about 20 volts. The important thing is, there is A-C at the output of the transformer.The second step I gave you is to measure the voltage across the capacitor C1 and tests for the D-C output from the diodes.Set the volt meter to 200 volts D-C, place the RED led on the [+] terminal and the BLACK led on the [-] terminal. Only one terminal may be marked. With power on and the trigger pulled the voltage should be about 28 volts D-C. The next step is going to be tricky; I dont know how Z1 is wired in your unit. It may be as shown between C1 and the NEGATIVE terminal or it may be on the [+] side of C1 and the POSITIVE terminal. Lets assume Z1 is as shown, move the BLACK led to the other side of Z1, that may be the wire going to the GUN or the wire going to the GROUND clamp depending on how the unit is configured, solid wire or flux core. There should be the same 28 volts D-C at this point.Last edited by transit; 07-25-2009 at 12:04 PM.
Reply:Fantastic troubleshooting directions for not having the welder in front of you. I think I could test out my Lincoln & see if it's performing up to specs using this instruction.Thanks for the question & answers, it's gonna help me in the future.MarkI haven't always been a nurse........Craftsman 12"x36" LatheEnco G-30B MillHobart Handler 175Lincoln WeldandPower 225 AC/DC G-7 CV/CCAdd a Foot Pedal to a Harbor Freight Chicago Electric 165A DC TIG PapaLion's Gate Build
Reply:Thanks Mark. Im bogged down. I have an adobe file that I cant up load because its too large. Im trying to get one page from the file in a form that will upload; it has the transformer and rectifier diagrams. Without that page post # 9 is meaninglessLast edited by transit; 07-25-2009 at 12:07 PM.
Reply:Originally Posted by transitHave you ever used the 50% trouble shooting rule? You have a circuit, with parts; ABCDEF in that order.F is not working. Test point D. If D works, the problem is to the right.If D doesnt work, the problem is to the left. Keep cutting the circuit in half until you find the problem.
Reply:Originally Posted by transitThanks Mark. I’m bogged down. I have an adobe file that I can’t up load because it’s too large. I’m trying to get one page from the file in a form that will upload; it has the transformer and rectifier diagrams. Without that page post # 9 is meaningless
Reply:[quote=transit;302595]I know this Miller manual is the wrong, but it dose have a wiring diagram that should be helpful. Go to page 33, figure 7-1 of the Adobe file, you will need to rotate the page clockwise and magnify the page to view it. Take note of the transformer in the upper right of the page [T-1]. The secondary of the transformer has three connections, x1, x2, x3. SR1 is the rectifier assembly, the arrow heads pointing to the right are the diodes assembly and C1 the capacitor, Z1 is the inductor. The instructions I gave you would have measured the A-C voltage from x2 to x1 and x2 to x3. That wire from the transformer to the capacitor that you mention is x2 to the bottom of C1.I think those A-C voltages are a little high and you may have measured the voltage from x1 to x3. If that is the case, the values from x2 to x1 and x3 should be half, about 20 volts. The important thing is, there is A-C at the output of the transformer.The second step I gave you is to measure the voltage across the capacitor C1 and tests for the D-C output from the diodes.Set the volt meter to 200 volts D-C, place the RED led on the [+] terminal and the BLACK led on the [-] terminal. Only one terminal may be marked. With power on and the trigger pulled the voltage should be about 28 volts D-C. The next step is going to be tricky; I don’t know how Z1 is wired in your unit. It may be as shown between C1 and the NEGATIVE terminal or it may be on the [+] side of C1 and the POSITIVE terminal. Let’s assume Z1 is as shown, move the BLACK led to the other side of Z1, that may be the wire going to the GUN or the wire going to the GROUND clamp depending on how the unit is configured, solid wire or flux core. There should be the same 28 volts D-C at this point.[/quot
Reply:this may work, no .
Reply:Ok, I can't beet'em, so I cheet. Attached ImagesVisio-135-2.pdf (22.6 KB, 112 views)
Reply:Originally Posted by duaneb55I typically start at A and move thru to F unless experience indicates the likely cause is at C or ?? but I can see where the 50% method would prove to be very effective in quickly determining which side of the 'fence' to start looking when in unfamiliar territory. Have probably done just that but never looked at it in the way you've aptly described it transit.
Reply:I scraped off the diagram and here it is. Also, I will take other pics and send them soon. I took the switch loose from the gun to check it last night. The wires looked pretty bad where they had been crammed back into the handle. They also had electrical tape around the connectors I guess to prevent a short. If the switch works for the wire feed and the gas, could it still be bad causing no power to the wire?I'm going out to try some more voltage testing and will send results later also. Attached Images
Reply:Originally Posted by transitThat would take too long; I have almost 10,000 devices in the corporate network.
Reply:Ok, I see whats going on. That rectangle to the right of CIRCUIT BREAKER looks to be a combination control board and rectifier assembly. My PDF diagram shows the detail electronic components. Now its a matter of matching my diagram with yours.
Reply:a few pics... Attached Images
Reply:Originally Posted by gregor If the switch works for the wire feed and the gas, could it still be bad causing no power to the wire?I'm going out to try some more voltage testing and will send results later also.
Reply:Take your voltage readings. That metal plate [heat sink] between the fan and transformer should have the diodes mounted on it.I thought my mig is tight to work on.Last edited by transit; 07-25-2009 at 02:40 PM.
Reply:Failed SCR transit? Heat sink temp switch failed closed/open?Don't mean to barge in and jump ahead.whispering under breath 50% rule. . .50% ruleMM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:That is what I'm thinking too. Don't want to jump the gun until I know more.Finding the failed components is half the work, what caused it to fall is the second half. Shorted cap or too much welding current, too many long duty cycles?Last edited by transit; 07-25-2009 at 03:29 PM.Originally Posted by transitThat is what I'm thing too. Don't want to jump the gun until I know more.
Reply:OK I just tried to take the voltage at the capacitor neg and pos terminals on the top of the capacitor-- is that correct. Now, my volt meter doesn't have a 200v setting but it does have auto ranging up to 600v, 10 MegaOhm setting so I tried it. Didn't blow the meter but the voltage was all over the place. Zero voltage when I first powered up, pulled trigger and split sec voltage of over 100v then voltage would go down to 0.9-0.5v fluctuating. Voltage would always come up when the trigger was released then slowly start coming back down. Did I do this wrong? Pretty much same readings at the wires to the gun.Now to check diodes. I don't see any way I can get in there to check them. Your not talking about testing where the wires attach are you?
Reply:OK I figured out I was attaching meter to white and black on corresponding sides instead of the main/common black on top. Now I'm getting 22v on 100A and 20v on 90A on all 4 wires.
Reply:BTW, those voltages at the "heat sink" were without the trigger pulled. There was no change with it pulled.
Reply:Originally Posted by gregorOK I just tried to take the voltage at the capacitor neg and pos terminals on the top of the capacitor-- is that correct. YES Now, my volt meter doesn't have a 200v setting but it does have auto ranging up to 600v, That's good, it switches ranges as needed 10 MegaOhm setting so I tried it. Huh? Didn't blow the meter but the voltage was all over the place. Zero voltage when I first powered up, pulled trigger and split sec voltage of over 100v then voltage would go down to 0.9-0.5v fluctuating. Voltage would always come up when the trigger was released then slowly start coming back down. Did I do this wrong? No, when the applied voltage is released the capacitor slowly discharges through the bleed resistor, that way you don’t have to worry about a flash. Pretty much same readings at the wires to the gun.Now to check diodes. I don't see any way I can get in there to check them. Your not talking about testing where the wires attach are you?
Reply:Originally Posted by gregorOK I figured out I was attaching meter to white and black on corresponding sides instead of the main/common black on top. Now I'm getting 22v on 100A and 20v on 90A on all 4 wires.
Reply:Originally Posted by gregorBTW, those voltages at the "heat sink" were without the trigger pulled. There was no change with it pulled.
Reply:sorry, 10MegOhm input DCV. That make more sense?
Reply:No the 22V is AC coming off the circuit board. Well thanks for all the help guys. I appreciate your time. Sorry I don't have the knowledge to put all your good information to work. Next step will be to buy a new welder, which is what I should have done in the first place.
Reply:you should have 20 to 22 volts DC at the cap. If your reading A-C the diodes are most likely shorted. The cap is Polarized. AC on the cap is not a good thing. Now if we have DC voltage at the Cap, 20-22 volts. Therefore it stands that we should have the same voltage across the WHITE and BLACK wires on the wire feed in the second photo because they are connected to the cap. If you trace the heavy lines on the print from the + and terminals on the cap, they go to the terminals of the wire feeder. The print shows a WHITEWHITE at the wire feeder, must be a type-o.
Reply:I up dated my diagram with what you should be seeing. Attached ImagesVisio-135-2.pdf (23.7 KB, 56 views)
Reply:Originally Posted by gregorNo the 22V is AC coming off the circuit board. Well thanks for all the help guys. I appreciate your time. Sorry I don't have the knowledge to put all your good information to work. Next step will be to buy a new welder, which is what I should have done in the first place.
Reply:Originally Posted by gregorsorry, 10MegOhm input DCV. That make more sense?
Reply:Originally Posted by DSWGregor, this is a great thread. I still have my old junky mig that died years ago. I've been following this to get a better understanding of the machine. I may just invest in the one part I know is bad and tinker with it, just to get a better feel for electronics. I wished I had paid more attention to this sort of stuff when I had the opportunity to learn years ago,transit & duaneb55 Thanks for the tutorial!
Reply:Gregor, I can understand your frustration, do you know anyone that can help you locally?
Reply:Originally Posted by DSWGregor, this is a great thread. I still have my old junky mig that died years ago. I've been following this to get a better understanding of the machine. I may just invest in the one part I know is bad and tinker with it, just to get a better feel for electronics. I wished I had paid more attention to this sort of stuff when I had the opportunity to learn years ago,transit & duaneb55 Thanks for the tutorial!
Reply:Although I plan to buy a new welder now (the reason I decided to buy a welder was my lawn mower needs a few welds on it and I'm always needing one for odds and ends jobs, so now would be a good time) I do still plan on trying to find the problem with this welder. I thought all along that I would eventually give it to my dad anyway. I'll try it again when I have some more time. Thanks guys.
Reply:Originally Posted by DSWtransit & duaneb55 Thanks for the tutorial!
Reply:This is what happens when water gets into a 30,000 watt power supply.That's a $ per watt! Attached ImagesLast edited by transit; 07-25-2009 at 09:34 PM.
Reply:Ever hear of the 50% rule for troubleshooting?Now would you attempt a repair or just replace the entire board in a case like that?They're at work but I have 3 PC boards from an industrial valve actuator that a tech() hit the 115vac control circuit with one leg of 460v in an attempt to operate the unit that look just like that. Something fried on each one as the 230v just kept looking for the next weak link. I was NOT a happy camper. Problem is he acted as if it wasn't his fault!MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Originally Posted by transityou should have 20 to 22 volts DC at the cap. If your reading A-C the diodes are most likely shorted. The cap is Polarized. AC on the cap is not a good thing. Now if we have DC voltage at the Cap, 20-22 volts. Therefore it stands that we should have the same voltage across the WHITE and BLACK wires on the wire feed in the second photo because they are connected to the cap. If you trace the heavy lines on the print from the + and terminals on the cap, they go to the terminals of the wire feeder. The print shows a WHITEWHITE at the wire feeder, must be a type-o.
Reply:Originally Posted by transitI have the same results searching for information on that model, very lean pickings. But until we find a manual we can do some diagnosing.Ok, here is what we know.A] The unit powers on.B] Wire feeds.C] The gas valve operates.D] Part of the control board operates.E] No welding power.We may conclude the problem centers around the main contactor, power transformer, rectifier, capacitor bank, inductor and connecting wiring. Possible problem with the heat control and the related circuits on the control board.Lets start with the oblivious.With power disconnected from the wall, remove the covers and look for any loose or broken connections. Look for any components that may have burned out.Have you ever used the 50% trouble shooting rule? Probably not. You have a circuit, with parts; ABCDEF in that order.F is not working. Test point D. If D works, the problem is to the right.If D doesnt work, the problem is to the left. Keep cutting the circuit in half until you find the problem.Lets take the rectifier as the halfway point.The output of the power transformer [heavy copper wire] connects to the rectifier. There should be 3 wires coming from the transformer, one each connected to the diode assembly on the rectifier and a common connected to the heat sink of the rectifier. Open the pressure roll on the wire feeder, no need to feed wire now. It would be easer if your meter leads have clips to make connections.Set the voltmeter to the A-C scale at 200 volts. Connect one lead to the common point on the heat sink and one probe to the wire connection to one diode assembly. With the unit plugged in, power on, squeeze the trigger on the mig gun. You should see about 20-25 volts A-C. Next move the test lead from one diode assembly to the other and repeat the test. Again you should see about 20-25 volts A-C. Does changing the heat control have any effect?
Reply:transit, duanneb55, DSW, and all others who have posted here,You've inspired me to continue. Plus, I went to tractor supply to pick up a Hobart Handler 140 tonight and they still don't have them. That is what I had intended to buy before I bought this Century. I'm sure getting a lesson in welder repair though.duanneb55,, I live in central KY.. Drinks are on me if anyone wants to come over and help me out..transit, the link below is the meter I'm using. I don't know anything about electrical but I read about it here and I'm pretty sure the setting I used for the DCV was correct, it just says 10MegOhm input there and DCV below it also.http://www.warehouseautoparts.com/Sp...0_sdw-461x.jpg
Reply:I'll jump in only because transit is off line right now gregor.The clarifications in your two posts above indicate one or more defective (open) SCRs (Silicon Controller Rectifier) or fancy name for a switchable diode. These would be mounted on that heat sink and are used to rectify the transformer AC to DC. Voltage before rectifier is AC and DC after. That's what transit was walking you thru - checking the voltage before and after.Pulling the gun trigger is supposed to cause the SCRs to activate (simple terms - close) and complete the circuit from the transformer to the welder output. The capacitor acts to stabilize the output voltage and prevent a sudden voltage drop when the weld process (arc) first starts.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:I think a lot of the problem is that I'm getting some of the terminoloy mixed up. For instance, when the "rectifier" was being referred to I was looking at my diagram and was thinking the "reactor" was the same thing? Then I was thinking the heat sink and the circuit breaker were the same thing? So the heat sink is just the metal plate on top of the circuit breaker? When I look at the diagram of my wiring and then look at the welder itself, it really doesn't look the same. Kinda like trying to read an x-ray if you don't know anything about them. Also when I check the voltage at the capacitor, would I need to check the voltage in and voltage out seperate? I think I asked this question before, but just wanted to make sure. Could I be getting correct voltage to the capacitor but not out of it? Seems like everything matched up with what it was supposed to be except I wasn't getting the correct DV voltage at the capacitor. |
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发表于 2021-9-1 00:44:17