Problems with Draper 135AT Turbo MIG

[pbrain]

Hello, i've just pulled my 135AT out of my van which has been sitting idle for a couple of years. When I put the welder in it was OK. tried to fire it up today, no spark. pulled the 'old' section of wire through, still nothing. Open the casing to look for loose connections etc. What I did notice however is that what looks like a thermostat on the transformer, the connector plug which has 2 wires, only half the connector is plugged in. It hasn't fell out because it has a locking groove. I didn't want to alter it and reconnect fully incase it shorts anything.
Does 1 wire to the thermostat seem right?

I've been looking around for a wiring diagram, but not been successful yet.

Thanks for reading.

 

[Cobbler]

Welcome to the Forum, be good if you could put a few details on the introductions at the bottom, any projects etc that your doing so everyone knows who you are.

I don't know anything about Draper machines, but it sounds like a thermal cutout to me, if so it would have 2 wires to it so it sounds to me that's somethings come adrift. I may be wrong on this, but I would have thought when too hot it should cut out everything but the cooling fan. Hope this gives you a clue where to start

I don't know who makes Draper machines, but they won't make them themselves, so if you can find out who you may find a diagram under another name. Someone in the know may be along in a minute.

 

[The_Yellow_Ardvark]

Drape welders used to be Clarks machines.

 

[Cobbler]

If it's a Clarke under the skin, here's a diagram

 

[pbrain]

Cheers Cobbler, I will get details up asap. I'll get a photo up of the transformer when I strip it down again. I've had nothing but problems with it. Even day one when it arrived it was broke (the control board was snapped in half!). Instead of sending it back I asked the seller to send a new board and i'll fix it myself. Then when that was sorted, the wire would keep gathering after the pinch-rollers. After much experimenting I got that sorted and had a play with it.
I'm a complete noob to welding and was hoping to get experience with this one. I'm trying to get my van back on the road and it needs a panel welding at the back (thieves wrecked the locking mechanism and so I'm plating it over and using servos to control the lock.
I'd like to be able to use the welder (or another one) for future motorcycle modding fun!
Back to the topic, it worked before it went in the van and no-ones open the welder, but when I opened earlier I noticed that there was a 2 pin plug connected to what looks like a thermostat, but it was only half-on, pushed on fully but using only 1 pin. I was tempted to reconnect it using both pins, but concerned it may cause a short. I was wondering if anyone had knowledge of these and knew if it was correct to use just half the socket?

 

[pbrain]

Here's a photo of the thermostat...as you can see, there's a pin not being used...no one has changed this and it did work before?!

 

[Cobbler]

I reckon the workshop gremlins have been in there, I can't see how it will ever work on one wire, if it would, the beancounters would not allow the second wire to be fitted. When you look at the picture, the plug looks like it's been fitted incorrectly as well, off to one side. The only thing I can think of, the thermal switch has failed in the past & someone has bridged between the plug connections to get it working & this has now dropped out.

I reckon if you bridge between the pins it will work or better still, put a meter across the thermal switch to check it's not gone open circuit or gone to earth on the transformer & reconnect it, it will work.

 

[pbrain]

I took the plunge and put the thermostat plug in it's right position, turned on and waited for the pop & smoke. Still nothing...
I then, while the cover was off measured the rectifier plates, these was giving 40-60vdc depending on the switch selection...so I know the transformer is OK.
I then left one probe on one plate and using a test meter followed the cables, the earth clamp was metered perfect from plate to clamp.
The other plate went as far as the brass block in the torch...
I could get a reading by wobbling the feed line...

So a bit of head scratching and I created a connection from the tab at the back of the brass block and wrapped it around the feed line, done 5 connections using 1mm copper cable, this metered fine. re-assembled the welder and it works (well it flashed on the test panel!) So hopefully when the weather knocks off and can crack on with the welding learning curve and hopefully some van repairs.
Appreciate the input from you guys and i'll be sticking around to learn and improve my welding kung-fu

 

[pbrain]

I reckon the workshop gremlins have been in there, I can't see how it will ever work on one wire, if it would, the beancounters would not allow the second wire to be fitted. When you look at the picture, the plug looks like it's been fitted incorrectly as well, off to one side. The only thing I can think of, the thermal switch has failed in the past & someone has bridged between the plug connections to get it working & this has now dropped out.

I reckon if you bridge between the pins it will work or better still, put a meter across the thermal switch to check it's not gone open circuit or gone to earth on the transformer & reconnect it, it will work.

I think my welder was put together on a Friday the 13th by Mr Bean!

 

[Cobbler]

Just for curiosity, if you still have the covers off, try pulling the plug back off the transformer & see if it still works, or maybe the thermal cutout goes from open to closed when it gets hot & is switched somewhere else in the circuit. I wouldn't have thought so, but you never know.

 

[pbrain]

The liner (where your red probe is touching) doesn't carry the current - it's supposed to go through the brass block, down the swan neck to the tip and thence to the wire.

Not sure how long 5 bits of 1mm will last before melting...

The electrical connection ended at the brass block, nothing after that. The method I've done works, I've managed to do some welding yesterday (many would argue the term 'welding' LOL!). 1mm solid copper wire will hand 10-15A per strand over 1 metre without noticeable heating. I'm using 5 strands over the distance of 15mm and with a low duty cycle...there should be no problems.

 

[pbrain]

Just for curiosity, if you still have the covers off, try pulling the plug back off the transformer & see if it still works, or maybe the thermal cutout goes from open to closed when it gets hot & is switched somewhere else in the circuit. I wouldn't have thought so, but you never know.

I tried to see if there was a product ID/code and reference it to see how it works. I've connected using both pins, re-assembled and used it yesterday. If I get chance this week (and remember) i'll send an e-mail to Draper and ask them about it. I wasn't sure if the tab was part of the circuit (like MOSFETS), fingers crossed it seems working, just need to spend some time to learn welding now.

 

[the snooper]

if you are getting voltage readings from the main rectifier but cant weld its a bad connection check and clean the connection to the work clamp and also any crimped connections on the earth (work clamp lead) even if they look good they often fail, a sure sign of this it getting voltage at the torch tip put your meter on the torch tip and the work clamp pull the trigger if you get a voltage that changes with the power settings you have a bad connection

 

[pbrain]

if you are getting voltage readings from the main rectifier but cant weld its a bad connection check and clean the connection to the work clamp and also any crimped connections on the earth (work clamp lead) even if they look good they often fail, a sure sign of this it getting voltage at the torch tip put your meter on the torch tip and the work clamp pull the trigger if you get a voltage that changes with the power settings you have a bad connection

I got good resistances from rectifier plate to earth clamp, so that was OK. I got good resistance reading from rectifier plate to the brass block in the handle. I got no reading at all to the metal guide, copper tip or welding wire.

 

[pbrain]

I don't see what the bits of wire are doing now tbh, so yes, they'll not melt.

The swan neck (bent metal tube with black cover) is the part that carries the current to the tip (small bullet shaped piece of copper that screws into the end that the wire comes through).

The coiled liner that your probe is touching is only there to guide the wire, if that's the part you were metering on I'm not at all surprised you had intermittent continuity.

Seeing as the magic pixies are making it to the brass block, and the swan neck is screwed directly into it, unless you've got excessive corrosion on either of the threads on that brass block there's nothing to stop said pixies running down the swan neck and splurging your wire into the metal.

I'd say that if the threads are clean your bits of wire are now superfluous - the action of stripping it to check probably cleaned up the connections (if they were actually the problem).

As an aside, you may well have the capability in the short lengths of conductor to carry nearly a hundred amps, but unless you did anything else that 'connection' made by wrapping around the terminal isn't a good mechanical joint - if they are carrying the weld current (unlikely now, see above) that joint will heat.

As mentioned before, the current only goes as far as the brass block in the handle. From the rectifier plate to this point is a very good connection (less than 1 ohm). I don't know what method is used to transfer the current from the brass block to the wire, but whatever it is, it doesn't work (The complete unit is very poor IMO). When I moved the metal guide about, there was an intermittent connection. Both the guide and the welding wire gave good resistances. So all I done is wrapped copper wire from the back of the brass block (where the power cable is connected to) and wrapped tightly around the wire guide, done this around 5 times. This provides a constant connection from the power supply cable to the welding wire.
The current rating of 1mm cable (10-15A) is based over the distance of 1metre. As cables get longer, the current capacity reduces due to the coppers' resistance. The distance of the copper wire in the handle is only 10-15mm, coupled with a low duty cycle and reduced voltage (40-60v) It should be fine for what I do.
When I get to do more serious welding (motorcycle modding), i'll either upgrade the whole kit or just replace the gun & liner.

 

[the snooper]

As mentioned before, the current only goes as far as the brass block in the handle. From the rectifier plate to this point is a very good connection (less than 1 ohm). I don't know what method is used to transfer the current from the brass block to the wire, but whatever it is, it doesn't work (The complete unit is very poor IMO). When I moved the metal guide about, there was an intermittent connection. Both the guide and the welding wire gave good resistances. So all I done is wrapped copper wire from the back of the brass block (where the power cable is connected to) and wrapped tightly around the wire guide, done this around 5 times. This provides a constant connection from the power supply cable to the welding wire.
The current rating of 1mm cable (10-15A) is based over the distance of 1metre. As cables get longer, the current capacity reduces due to the coppers' resistance. The distance of the copper wire in the handle is only 10-15mm, coupled with a low duty cycle and reduced voltage (40-60v) It should be fine for what I do.
When I get to do more serious welding (motorcycle modding), i'll either upgrade the whole kit or just replace the gun & liner.

the swan neck should take the power from the brass block to the tip, brass swan neck should have a direct connection to the brass block, no insulators