Telwin/ NU 100/1 Mig torch conversion

[Trebor01]

I am in the process of converting my Telwin/NU mig 100/1 welder from a live torch to a non live torch.

I have a number of questions

I need to install a gas solenoid where do I get the power from for this?

The new non live torch has two wires coming from a switch in the torch, where do I connect these two wires to?

Does anyone have a wiring diagram that shows the best place for connections to be made??

Any assistance would be appreciated.

 

[rtbcomp]

Welcome to the forum.

You will also need a contactor or relay capable of switching 20-25 amps.

A circuit diagram of the machine would be useful, but at a guess I'd say it would be something like this:



The contactor's contacts will have to switch the power to the big transformer and the gas valve (use a mains operated valve), so connect the gas valve between the pole connections on the power selector (range) switch(es), and the contactor so that it switches the power to the range switch(es), but leaves the auxiliary transformer (if fitted) permanently powered up.

Your machine may not have a PCB and/or auxiliary transformer, instead it may take the motor power from the secondary of the large transformer via a rehostat. How we connect the switch to the contactor depends on the setup on your machine.

Could you let us have some photos of the inside?

 

[Trebor01]

Hi

Thanks for the reply, I will post some photos later today hopefully.

Thanks again

 

[Trebor01]

Hi some photos of my welder plus I have found a copy of the circuit diagram, I trust these provide the information?

Regards

R

 

[rtbcomp]

It looks to me like that welder shouldn't have a live torch.

Are we talking at cross-purposes? A live torch is one where the welding voltage is available at the torch even though the trigger isn't pressed.

 

[KemppiFrog]

It looks to me like that welder shouldn't have a live torch.

Are we talking at cross-purposes? A live torch is one where the welding voltage is available at the torch even though the trigger isn't pressed.

Are you sure? Can't see a contactor in that diag. To the left of the transformer are the 1/2 Hi/Lo switches. I had a Telwyn 110 years ago ( '85?) with live torch, but it did have a gas solenoid.

 

[Trebor01]

Hi

There was a gas valve in the handle of the old torch, when pressing the trigger there was a very simple switch which took power from the main welding lead to a single thin black wire on the other side of the switch, which can be seen in the wiring diagram.

Apart from this gas valve in the handle the gas tube ran through the lead back into the machine and out the back to the gas regulator attached to the top of the gas bottle.

I have assumed this is a live torch as there is a continuous lead running from the rectifier to the head of the torch

My welder is an old machine (95) but is in good condition as it has had little use .

When it did fail, it was an O ring in the cheap gas valve that came out of its seating and I have been unable to get a replacement torch of the same design.

 

[rtbcomp]

Are you sure? Can't see a contactor in that diag. To the left of the transformer are the 1/2 Hi/Lo switches. I had a Telwyn 110 years ago ( '85?) with live torch, but it did have a gas solenoid.

Some welders don't have a contactor, they use a relay on the PCB instead.

...
I have assumed this is a live torch as there is a continuous lead running from the rectifier to the head of the torch

...

It's the primary of the transformer that will be switched by a relay/contactor. Connections 6 & 7 on the PCB are in the primary circuit which leads me to suspect the relay on the PCB switches the primary of the transformer.

Can you do an experiment? Set the welder up to weld and spool a couple of inches of wire out, release the trigger and touch the wire onto the earth clamp. If you get sparks you have a live torch.

Whether or not you have a live torch determines how the valve is connected.

 

[Sean]

that all looks horribly familiar to me as a SIP owner. The circuit board thats hanging off the back of the wire speed knob has a relay on it, the clear plastic lego brick thing Im sure that controlls the switching of the welding current from the torch contact.

theres a simple way to fnd if its a live torch, without pulling the trigger touch the tip with the earth clamp.

have a look through some of the SIP modification pages there was a chap that put a euro torch on one theres a multi pin plug with various coloured wires and im sure thats where you need to tap in for torch triggered 12~24v

 

[Trebor01]

Hi

Unfortunately the welder is not working as I have already replace the lead with one from ebay! There is a relay on the speed control board which activated when the trigger was pushed. The new torch consists of a micro switch with two wires, welding wire sleeve, gas pipe, power lead. The main question is where do I connect the two wires from the new switch. There was a single wire in the old torch which connected to the wire feed board?
Not sure if this helps?

 

[rtbcomp]

OK, so we'll assume it's not a live torch, in which case

Connect the two wires from the trigger in place of S4 in the diagram, it doesn't matter which way round they go, connections 1 & 3 are probably the best places to make the connections, leave the wire on 3 connected, the wire on 1 may be removed and insulated (it carries the +ve welding voltage).

Connect the solenoid (mains operated) across Pin 2 on the mains switch (S1) and C1 on S3. Pins 6 & 8 on the PCB may be the easiest place to make the connection.

 

[Trebor01]

OK thanks i'll give this a try and keep you posted on how it goes, thanks for the info.

 

[KemppiFrog]

Some welders don't have a contactor, they use a relay on the PCB instead.
.

Ah, thanks for that
KF

 

[Trebor01]

Hi

Welder now back together with new gas valve fitted. Rewired as suggested but I can get no reaction from the welder or the new solenoid when the trigger is pressed? any suggestions? I have wired the solenoid in but the positive and negative terminals are not marked so I have assumed this does not matter which way they go round?

Thanks

R