Another Tradesmig 160 with no Arc

[eddie49]

Those voltages on the primary and the 220v tapping are correct. The main thing is that the 220 is not too high. There is nothing to explain why both the contactor and the fan have failed. Maybe the fan failed long before the contactor did. Actually, have you tried giving it a spin when power is on, or disconnecting the two wires to the fan and checking resistance to see if it is in fact burnt out? Maybe it is just stuck, with a dried out or worn bearing.

When the new contactor arrives, check the label on the coil to confirm that it is really 240v, and maybe measure the coil resistance for future reference.

[ I use a massive Siemens contactor to supply power to our immersion heater, since dinky plug-in time switches do not last long running a 3kW load. The time switch now controls the contactor, so the contactor coil runs off 240v. To my surprise the coil resistance is 1015 Ohms, much higher than I expected.]

 

[Sauzee]

I have to admit eddie49 you are a power of knowledge with electrics i have sorted a couple of welders through the years but easy things like changing a relay or replacing diodes on my SWP 180 which i think is a top class machine i also have a 200amp 3 in 1 inverter mig which i like the stick function on
Thanks again i must be due you a few beers by now

 

[Sauzee]

Hi eddie49 i got the new contactor today i measured the coil it was 56 ohms the only problem i have is that the numbers are not the same on the connectors and there are less i connected all the corrosponding numbers but 2 different numbers A2 had a loop wire to 14 which is 22 on the new one and 13 which is now 21 but has a wire in it
Any help please dont want to blow new connector
Thanks

 

[eddie49]

I would not rely on using the numbers on the old part to equate to the numbers on the new one. Some numbers may be the same, but it is really the function that is important.

The contactor has three functions:
1. Operating coil - 2 wires.
2. Power to the main welding transformer On/Off - two pairs of contacts - for Live and Neutral. Normally Open ( NO ) contacts.
3. Capacitor bleed resistor - two pairs of contacts on the old part, only one pair on the new one. Normally Closed ( NC ) contacts.

There should be numbers printed on sleeves on all of the wires. The connections are shown in the wiring diagram on page 11 of the manual that I linked to in post #6.

1. For the coil:
there are two terminals, marked A1 and A2 on the new contactor. There should be two wires with number "44" on them. One of those wires goes to the gas valve, the other goes to pin B1 on the connector for the PCB. Both these wires should be connected to terminal A1 on the new contactor.

There should be two wires numbered "42". One goes to the gas valve, and on to the fan. The other "42" goes to the main On/Off power switch, to the auxiliary transformer, and to one of the main On/Off power contacts on the contactor ( this is the contact set used to switch the Neutral ), where that end of the wire has number 42 on it. Both these wires numbered "42" should be connected to terminal A2 on the new contactor.

[ If you do not find two "42" wires but only one, it may be that one wire starts at terminal A2 of the contactor and then goes point-to-point to the locations I mentioned. You could prove this by using a meter set to check Continuity, with an audible buzzer.]

2. Main Power On/Off:
the new contactor is designed to switch a 3-phase circuit, so it has 3 sets of main high-current contacts. Only 2 will be used, for Live and Neutral. The terminals normally used for power input are at the top, labelled L1, L2, and L3, and the outputs after the three switches are T1, T2, and T3. They also have numbers: when the contactor is switched on, terminal 1 at the top joins to 2 at the bottom, 3 joins to 4, and 5 joins to 6.

You can decide to use any two out of the three available sets of contacts. For example, L1 ( 1 ) to T1 ( 2 ) and L2 ( 3 ) to T2 ( 4 ).

In this explanation I am using the terminals at the top of the contactor as inputs to the two sets of switching contacts, and the terminals at the bottom as the outputs. However, the wires may originally have been placed the other way, and so they may not be long enough to reach. In that case, just reverse "top" and "bottom" in my wording. These contact sets are just On/Off switches, it does not matter which "end" the wires go in or out. The important point is that one set is for Live and the other set for Neutral.

The wire marked "39" is Live, and can go to top terminal number 1, L1. The corresponding output is bottom terminal number 2, T2, and this should have wire number "15" connected. ( This wire goes to the main voltage selector block, with the bolted solid metal bars for 220v or 240v selection.)

The input for the other pair of contacts ( Neutral ) is top terminal number 3, L2. This should have a wire "42", from the choc block for the input mains cable. There should also be a second wire numbered "42", going to the auxiliary transformer and the contactor coil terminal A2, as mentioned above. Both these "42" wires go to contactor terminal number 3, L2.

The output screw terminal of this pair of contacts is labelled 4, T2, at the bottom of the contactor. It should have wire number "5" connected. This wire goes to the 6-way rotary voltage selector switch.

3. Capacitor bleed resistor:
hopefully you have located the wirewound ceramic 15 Ohm resistor. On the original contactor it was joined between the two sets of normally-closed contacts. The new contactor only has one set of NC contacts - marked NC, 21 at the top and NC, 22 at the bottom. There were two wires, both numbered "90". One of these ( either one ) should go to NC, 21. One end of the resistor then goes to terminal NC, 22. The other end of the 15 Ohm resistor should be joined to the other wire marked "90". That will have to be a soldered and insulated joint, or use a screw-terminal connector ( barrier strip ). The resistor is now only going to be supported by one of it's two leads. If you decide that it needs more support, e.g. a cable tie, bear in mind that it can get hot.

I hope that the existing wires do have the numbered sleeves on them. You may need to cut cable ties or use a meter set to Continuity to trace the wires and confirm where they go. If anything is not clear, please let me know.

 

[DSR]

Hi eddie49 i got the new contactor today i measured the coil it was 56 ohms the only problem i have is that the numbers are not the same on the connectors and there are less i connected all the corrosponding numbers but 2 different numbers A2 had a loop wire to 14 which is 22 on the new one and 13 which is now 21 but has a wire in it
Any help please dont want to blow new connector
Thanks

Hi, Eddies done a brillianty job and he's given lots of numbers here and the resistance of the coil is bang on in the range he stated. I don't have one to compare it with but it just 'feels' too low to me, I'd have thought it would have been nearer the midldle/top of Eddie's range. Can you just confirm that you definitely clicked 240V when you chose the contactor and/or it has 240V written on the coil somewhere.

There's nothing wrong, I'm not criticising or anything like that, it's for my peace of mind that I'm interested. Double checking now and confirming it's correct will be a good outcome, finding it's wrong by shoving 240VAC through e.g. a 24VDC coil will void the warranty/return

 

[Sauzee]

Hi eddie49 Thanks again for all your help i managed to put all the wires in thanks to your info only a couple different as had 4 number 42 and i had a wire 51 coming from voltage switch which i thought may have been number 15 with the clip reversed.Anyway i connected it all up connector was pulling in when switched but still no arc i also checked to make sure it was 240v as DSR said.On the end of the earth lead it is connected to another transformer with a large cable connecting to earth.Above it there is 4 wires marked 100 with earth to chassis taking a reading from 100 wires to trigger is 10 volts and 23 volts when trigger pressed but no reading from earth lead
Thanks again
Sorry number 51 runs to main transformer

 

[Sauzee]

Sorry again eddie49 you were correct 51 was indeed 15 going to metal 220 volt strip connector the only other thing was i had a wire from A2 loop to terminal T2 wire number 5 i have not connected this yet do you think this is why no Arc
Thanks again

 

[eddie49]

Hello, I am glad you are making good progress, with no smoke yet and all your fingers are still intact !
As you have found, the "51" was in fact "15", and it is the Live feed out from the contactor bottom terminal number 2, T2, going to the main transformer via the 220/240 voltage selector link block.

The four wires with the number "100" are AC mains earth wires that take chassis earth out to individual mains-driven components, such as the gas valve and the fan.

The work return cable and clamp is a different circuit. Some people call it the "Ground" or the "Earth Clamp", but it is actually the negative output from the rectifier, on the secondary side of the main welding transformer. It has nothing to do with mains earth or the chassis of the welder. The rectifier negative is connected by heavy flexible cable to the capacitor bank ( 6 x 10,000 uF capacitors ). The negative and positive terminals of all the capacitors are bolted together with aluminium busbars. Then the negative goes to the inductor ( or choke ). It looks like a transformer, but it has only one winding of heavy copper strip. From there the negative goes to the Dinse socket on the front panel, for the work return cable and clamp.

To check whether a MIG welder has the correct output, you measure the voltage from the tip of the MIG torch ( positive ) to the work return clamp ( negative ), and then step up the positions of the voltage selector switch. At each step, press the trigger and check the voltage. It should start at about 15 volts DC and rise to about 30 volts.

The "unconnected" wire that you mention is a bit of a puzzle.

The A2 side of the contactor coil needs a Neutral feed, which comes from the top terminal of the contactor, number 3, L2, using a wire with the number "42". If this wire was not correctly wired, there would be no Neutral at the contactor operating coil, and it would not be pulling in when you press the torch trigger.

The output of the L2 ( number 3 ) Neutral pair of contacts is the lower terminal screw, labelled T2 ( number 4 ), at the bottom of the contactor. It should have wire number "5" connected. This wire goes to the 6-way rotary voltage selector switch, and then on to the transformer. It is true that with this number "5" wire not connected, there will be no power to the main welding transformer, and therefore no arc. However, this "5" wire should not be going anywhere near the contactor coil A2 terminal.

 

[Sauzee]

eddie49 you are a wealth of knowledge on the wiring the unconnected wire i spoke about was was connected on a splice going from A2 to the connection that has number 5 wire connected to it.When i read the torch and earth clamp i get no reading but as i say when i put the negative lead from the multimeter on the earthed chassis i get 10v rising to 25v when trigger is pressed.When i check voltage on wire 15 when it is removed from connector it reads 5v The connector is pulling in as can see it move and can hear gas valve and wire motor runs The top chock block on the auxillary transformer i think the numbers are 47/48 and 52 have 26v now
Sorry if it is a bit vague but i will try some other checks tomorrow
Thanks
Sorry eddie49 i have 4 number 42 i have connected them all in A2 is that correct and should wire 15 be live when trigger is pressed or should it be live from transformer
Thanks again

 

[eddie49]

All these notes about the wiring at the contactor are based on the TM160 wiring diagram on page 11 of the manual that I linked to in post #6.
The output from the auxiliary transformer of 26 volts AC that you measured at the top choc block, from terminal 47 or 48 to 49 or 52 is correct.This gets rectified to DC on the board and runs the electronic logic there and also the wirefeed motor.

The contactor operating coil terminal A2 should have a wire numbered 42. There are a lot of locations and components that have a "42" wire - e.g. the gas valve, the fan, the main On/Off power switch, the auxiliary transformer, and the main Neutral contact set on the contactor - terminal number 3, L2. These "42" wires may go point-to-point, or they may all start at the contactor A2 terminal. That explains why you have four wires with that number, and it is OK for all of them to join at A2.

No DC voltage from the torch tip to the work clamp means the main transformer still is not getting switched on. The main transformer secondary winding is isolated from the primary, and from mains earth. It has a low-voltage high-current AC output, which gets rectified to DC and feeds the brass block of the Eurotorch socket ( positive ) and the work return cable ( negative ). Both these wires, positive and negative, are ( should be ! ) totally separate from the chassis or the casing. They are "fully floating". Measuring some voltage on the positive ( torch tip ) with respect to the earthed chassis is an error, there should not be any voltage between those two locations. It is possible that a sensitive digital voltmeter shows a stray voltage due to a slight leakage, caused by some poor insulation, but this voltage is not real power. It can only drive enough current to make the meter show a reading.

The main transformer gets Live and Neutral from the two sets of contacts on the contactor. At the top, Live should be on the left, and Neutral to the right of that. There should be 230/240v AC between L1, ( 1 ) and L2 ( 3 ) when power is on. When the torch trigger is pressed, the contactor should pull in, and then this voltage should appear across T1 ( 2 ) and T2 ( 4 ). It is fed to the main transformer via wire number 15 ( Live ) and wire number 5 ( Neutral ). If you can see this AC voltage there, then the transformer should be on, and you should be able to get an arc at the torch tip.

The voltage across wire number 15 and wire number 5 should be 240v AC mains, but only when the contactor closes. Both wires go to the transformer only. Wire number 5 should not be spliced with a wire going to coil terminal A2.

 

[Sauzee]

Hi eddie49 sorry for making you explain this to me so many times you are correct (as always) 15 and 5 are live when conntactor pulls in.All voltage is as you said the only thing i cant get is the torch live with earth clamp i can read 10-12volts on neutral and tip or bar attached to wire feed rising to 60volts when trigger is pressed sorry to be a pain do you think the diodes may be at fault
Thanks
I checked diodes readings were left to right were 478/468/472 and 480ohms all reading only one direction

 

[eddie49]

There shouldn't be any voltage between the secondary circuit ( positive or negative ) and any part of the AC mains circuit ( Live, Neutral, Earth, case of the machine, etc ). The transformer secondary is supposed to be insulated ( and isolated ! ) from the primary.
Additionally, there should be 15v to 30v DC across the torch and the work clamp, controlled by the rotary voltage selector switch, but nowhere near 60 volts. Is that 60 volts AC or DC?

This could be an insulation fault. Try disconnecting both thick secondary wires where they cross from the transformer to the rectifier diodes. Make a note of where they go, and insulate them from each other and the rest of the machine. Then check the AC voltage across those two thick wires. It should be similar to the DC range that we are looking for - about 15 to 30 volts AC, when the trigger is pressed, and controllable in steps by the rotary switch.
From either side of the secondary, i.e. those two heavy wires, there should be no volts to the chassis of the machine.

If you do not get the expected low AC voltage on the secondary, or you do get any volts to the chassis, then the main transformer could be burnt or partially shorted to earth. Switch off and unplug the machine, set your meter to Resistance, and measure across the two thick secondary wires. It should be a very low value, close to zero, i.e. about 0.01 Ohms - not infinity ( "1 . " ).
Then measure resistance from either of the secondary wires to the chassis. It should be a very high value - hundreds of thousands or millions of Ohms.

 

[Sauzee]

I have checked the two main cables on the transformer shows 0volts even when selector switch is turned there is 00.1ohms resistance between both wires but no reading from any wire to chassis earth so is that a suspect Transformer as you may have thought
Thanks for all your help again eddie49

 

[eddie49]

OK, so nothing coming out of the secondary, but it is not burnt out. We need to check if there is any mains reaching the primary from the contactor and through the wiring.
In post #17, the second photo shows the voltage selector board. Put one end of your meter on the left-hand brass bar, which is bolted to wire 15. Set the meter to read AC mains. Try to find wire number 5 at the 6-way voltage selector switch, and put the other meter lead on it. Wire 5 will be attached to one of the terminals on that switch, but may be underneath and not accessible. Failing that, use the other end of wire 5, which should be on screw terminal T2, number 4 at the contactor. Plug in, switch on, press the trigger. The contactor should pull in, and there should be 240v AC mains across wire 15 and wire 5 - this is the primary of the transformer, but via the 6-position switch.

 

[Sauzee]

Hi eddie49 when checking the 6 pole switch and turning it while connecting 15 and 5 wires on the multimeter and pressing the trigger and 0 volts but a couple of times when turning the switch i got 8volts neutral and 15 gives me 240volts
Thanks again

 

[Sauzee]

I think i may have been an Ass eddie39 as i have just thought (in the early hours) that i have no number 42 (neutral) opposite terminal 5 so in the morning i will connect it and let you know
You have been a great help explaining all the details of the electrics

 

[eddie49]

Ref. no neutral: I did think that might be the case, since the results were "8 volts on Neutral and 240 on 15" - i.e. Live.
Rather than two values, there should only be one result - the voltage across the two points mentioned - in this case, wire 5 and wire 15. It sounds as though you have one end of the meter on Earth.

 

[Sauzee]

Hi eddie49 quick update tried all the combinations no different out of the 4 no 42 only one was a true neutral others were fed from the neutral from the mains
So i took a feed from L2 opposite to no 5 wire and looped it to A2 and switched it on hey presto worked right away so that must have been why it had that original loop wire
But i would never have reached any solution if it was not for your tremendous help i can not Thank-You enough
Top Bloke
Thanks John

 

[eddie49]

John,
Thank you for the update, and your kind words. I am really pleased that your welder is working now, and that you persevered through all the troubleshooting steps and were able to solve the last issue and have the satisfaction of reviving this good-quality machine.

In theory all the "42" wires start at the choc block for the mains input cable.
[ The brown Live should go to 36 at that block; this becomes 39, and then after the contactor it is 15, to feed one end of the main transformer.]
The blue Neutral is joined to 42 at the block, and it goes to one side of many components ( the auxiliary transformer, the gas valve, the fan, coil terminal A2 at the contactor ), but also L2 ( number 3 ) at the contactor. After the contactor it becomes wire number "5", and feeds the other end of the main transformer primary, via the 6-way step switch. It sounds like somehow this last link ( L2 ) was missing until you joined it to A2. All's well that ends well !
Best regards, Eddie