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Need some help please, we moved it from one side of the garage to do some work, completed the work and moved it back, started some other work, at the same time the sheet metal screw on the body sparked against the metal work table and the screw fused itself to the table, and now the machine welds only on maximum, low setting works fine, med and high amperage only works on max, manuals says the following.1. Welder not properly grounded, I've never had a separate ground on the machine before, the ground wire from the breaker box grounds the frame (unless the breaker box has lost its ground), the manuals talks about another ground."The work terminal must be connected to a ground within ten feet of the welder, using one of the following methods:a. A metal underground water pipe in direct with the earth for ten feet or more.b. A 3/4" galvanized pipe or conduit or a 5/8" solid iron or steel driven at least eight feet into the ground.2. Diodes or SCR's control rectifier.3. Capacitors C201, 202, 203, 204 in control rectifier open or disconnected.4. Free wheeling diode open or disconnected.5. PC Board failure.6. Current control rheostat faulty.7. Output By-pass capacitors open or disconnected. 8. Control current current sensing resistor or lead broken.I have no idea which one to start with. The hand amptrol seems to be fine, I can do control at TIG to rule that out. So any idea's?
Reply:Bump on where to start. When I mean max is it always welds with max current no matter where the amp dial is or what position the amptrol is in. Once it creates the arc just blows right through the material.Last edited by kazx9r; 04-15-2012 at 06:12 PM.Reason: none
Reply:Is it hardwired? If so, are you sure you rewired it correctly?The case being hot means that there is a short, or miswiring, somewhere. That is not something to be taken lightly.My bet is something cut into some hot wires somewhere, and it hasn't ever been grounded correctly(if you haven't miswired something).Manufacturers go to great lengths to isolate the hot stuff from the case for obvious reasons.
Reply:put it on the other side of the garage duh
Reply:Originally Posted by bighillIs it hardwired? If so, are you sure you rewired it correctly?The case being hot means that there is a short, or miswiring, somewhere. That is not something to be taken lightly.My bet is something cut into some hot wires somewhere, and it hasn't ever been grounded correctly(if you haven't miswired something).Manufacturers go to great lengths to isolate the hot stuff from the case for obvious reasons.
Reply:I don't know why they would specify a second ground, except for use with a generator. My generator specifies the use of a grounding rod, because everything needs to be reliably connected to the ground.If the screw arcing happened when you actually started welding, the short could be on the welder side of the things(and the ground lead might not have made electrical contact).
Reply:Thanks I'll report back.
Reply:On a TIG welder. the use of the word ground can get confusing.1st ground, comes to the welder in the power cord. Comes from the main ground buss in the electrical service panel. Main purpose is to make the case at ground potential and safe to touch. Plus if a power wire shorts to the case it will cause the breaker or fuse to trip real fast and keep you from getting shocked or killed.2nd ground. is the weld ground or work connection. allows the weld current back into the welder and completes the current path. No weld arc with out it.3rd Ground, Is the HF ground should come from a ground rod next to the welder. it is connected to the welder case and any metal tables, building walls and electrical conduits.The purpose is to give the HF a path to ground and keep it from damaging electronic equipment near by. Does not replace ground #1.Get an ohmmeter and measure both weld terminals to the welder case. must not be 0 ohms.If this is the TIG 250. It sounds like the control pcb has a shorted power transistor and is putting full reactor control current to the reactor. The satiable reactor fails to low output.The sister system, the mag amp fails open. A short in the weld circuit to the case should hurt the control system, unless one of the control pot wires is also shorted to the case.Post your code number If you need more help.
Reply:Originally Posted by ccawgcOn a TIG welder. the use of the word ground can get confusing.1st ground, comes to the welder in the power cord. Comes from the main ground buss in the electrical service panel. Main purpose is to make the case at ground potential and safe to touch. Plus if a power wire shorts to the case it will cause the breaker or fuse to trip real fast and keep you from getting shocked or killed.2nd ground. is the weld ground or work connection. allows the weld current back into the welder and completes the current path. No weld arc with out it.3rd Ground, Is the HF ground should come from a ground rod next to the welder. it is connected to the welder case and any metal tables, building walls and electrical conduits.The purpose is to give the HF a path to ground and keep it from damaging electronic equipment near by. Does not replace ground #1.Get an ohmmeter and measure both weld terminals to the welder case. must not be 0 ohms.If this is the TIG 250. It sounds like the control pcb has a shorted power transistor and is putting full reactor control current to the reactor. The satiable reactor fails to low output.The sister system, the mag amp fails open. A short in the weld circuit to the case should hurt the control system, unless one of the control pot wires is also shorted to the case.Post your code number If you need more help.
Reply:All the resistors are in spec but one what I think is transistor 2N5815 has a different resistance reading than the other 2N5815 but I think because they are circuited differently, so I have no any idea. Everything else has continuity. I don't know where to start looking, anyone?Last edited by kazx9r; 04-19-2012 at 11:00 PM.Reason: none
Reply:After doing some more thinking, I don't think its the control board, I'm going to move the welder and take a volt meter to the case while welding and then open the wire wiring, I'm thinking something is going on in this area because a few weeks back my Mitre saw wire melted and perhaps something hot near the table.
Reply:Think i made some progress the terminal is hot to the chassis, i thought i'd double check, the check before seemed the bolt was welded isulated but after checking several locations the terminal to chassis shows continuity.thats all i had time for, will report back.
Reply:send it to lincoln they will fix it
Reply:Originally Posted by mafiacustomzsend it to lincoln they will fix it
Reply:The other thing I noticed was one of the capacitors in the Amptrol shows continuity and the other shows a ohm reading. Which one is it suppose to be? I think I have to take the capacitor out of the circuit to check it.
Reply:Had a technician come over $40 for a diagnosis, he said he'll come back with some more equipment a schematics, I'll report back.Last edited by kazx9r; 04-22-2012 at 04:44 PM.
Reply:What a waste of $40, only thing I got out of it was the same answer and a diagnosis manual, back to square one. But one thing I did learn that 3rd ground is important and the machine has sparked against the tanks before, so I'm glad it stopped working now, now I can find a good ground and make the setup a lot safer.Last edited by kazx9r; 04-23-2012 at 10:04 AM.
Reply:I talked to Lincoln Electric, they said its an SCR on the PCB because it has max arc on LOW, MED and HIGH, since its only having the problem on MED or HIGH they suspect a SCR or two on the PCB, doesn't make any sense to me.....they said to be sure disconnect the PCB and strike an arc and it should be a weak arc on all three settings. They also stated it shouldn't have continuity from the power terminal to the case. They recommend disconnecting one system at a time to find the short. Also, the short does not go away even if every wire on the PC board is disconnected, airflow board as well, when I switch to DC its fine, fine meaning no continuity between the terminal and case.I need to check my friends TIG because it was on DC when I checked it, can anyone check resistence on there TIG from the power terminal to case has to be on AC?
Reply:To test capacitors, they should have one leg disconnected from circuit, then short the two legs momentarily to drain the volts. Set your meter to ohms or diode check (diode check puts out more breakover volts). Initially your meter will show a short but as the cap draws dc volts from your meter, the short goes open (caps block dc after charging). The cap should now be charged. Set your meter to volts and check the cap. The meter will show a voltage at first but the cap is slowly draining thru the meter. This test will not tell you if the caps are within tolerance but will show if the cap is shorted or open if the cap doesnt charge(ohms) then discharge(volts). If the SCR failed, it makes sense since it controls power flow but I really dont know. Is the SCR shorted open or conducting all the time? Also, it sounds like you have a ground issue?Last edited by Insaneride; 04-23-2012 at 11:16 AM.Reason: missed sequence
Reply:Nice, I'll get into it when I can. All I know it has continuity, so I'll have to take it out to perform the test.I firmly believe its a ground issue, i'll start disconnecting one wire at a time until I find something.
Reply:A word of caution about measuring voltage on your caps; if they are charged, they can bite. Also, dirt,sweat and grease on your hands can be a conductor for voltage to arc over if close enough but likely you have bleed resistors
Reply:Originally Posted by bighillI don't know why they would specify a second ground, except for use with a generator. My generator specifies the use of a grounding rod, because everything needs to be reliably connected to the ground.If the screw arcing happened when you actually started welding, the short could be on the welder side of the things(and the ground lead might not have made electrical contact).
Reply:Thank, now that I think about it more, I've seen sparks to the metal table and ground before, I thought it was just spatterAnd you know what when it did spark against the table the work ground was not hooked up to or near the work piece.
Reply:Originally Posted by InsanerideTo test capacitors, they should have one leg disconnected from circuit, then short the two legs momentarily to drain the volts. Set your meter to ohms or diode check (diode check puts out more breakover volts). Initially your meter will show a short but as the cap draws dc volts from your meter, the short goes open (caps block dc after charging). The cap should now be charged. Set your meter to volts and check the cap. The meter will show a voltage at first but the cap is slowly draining thru the meter. This test will not tell you if the caps are within tolerance but will show if the cap is shorted or open if the cap doesnt charge(ohms) then discharge(volts). If the SCR failed, it makes sense since it controls power flow but I really dont know. Is the SCR shorted open or conducting all the time? Also, it sounds like you have a ground issue?
Reply:I rechecked capacitors C201-204, they work as written, once charge, the voltage reading starts high and slowly drops down to zero.Next I'll check the capacitors in the amptrol, and then move onto the other items4. Free wheeling diode open or disconnected, checked these.7. Output By-pass capacitors open or disconnected, no idea where to locate this?8. Control current current sensing resistor or lead broken, I think this is the amp control on the TIG.Last edited by kazx9r; 04-25-2012 at 08:35 PM.Without being there, Im in over my head compared to the xperts here but, it sounds like its your SCR's are blown in the full on mode. It sounds like they are full on all the time? Do you know how to check a diode? An SCR is a diode with a trigger or third lead. Determine the trigger then check like a regular diode(both polarity). I dont know an easy wway to check the trigger but, normaly I dont like to shotgun replacement parts but replacing/shotgun the SCR couldnt hurt if you instal correctly. Look into the ECG data book for the equivalent SCR specs. I will look into trigger teststing.
Reply:I'm performing a few other tests, will report back soon.
Reply:The SCR's should be open or not conducting until the gate is triggered. It sounds like they are on or triggered all the time. I think you said they were conducting, this should not happen until the gate is triggered.
Reply:I only did a simple short test on the SCR, when I flip the leads, it does show a reading but I need to check it in diode mode of the MM.So far I've been checking voltages without the triggerwire 210 to fuse 130VACwire 213 to fuse 130 VAC210 or 213 to SCR plate = 70VAC, 57 VDC210 or 213 to diode plate = 70VAC, 57 VDCThe one thing I did notice was the bottom of the humungous coils (saturate reactor?) in the welder are black, like overheated, I've taken each of them out of the circuit (or as much as I can), and measured the resistance as 3 ohms on each of the windings, so that is really low and perhaps why this machine is about to take a dump, anyone?Sorry I meant to say the flux band is overheated not the windings.Last edited by kazx9r; 04-27-2012 at 11:12 AM.
Reply:Sorry again it is the winding, totally trashed, took it out of the circuit and get a good ohm reading on all the other coils and no shorts, this one also shorted to the iron core, a few theories that caused this.1. A lot of metal cutting in my shop and I saw a lot of metal debris wedged on those, they probably got hot enough to burn the insulation and arc to the iron core.2. The coil got hot enough to burn the insulation and arced against the core.What a sad ending. Atleast I found the problem.Last edited by kazx9r; 04-27-2012 at 08:44 PM.
Reply:After doing more research, only the DC control winding is shown. The full arc seems to make sense now. |
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