151TE constant live on torch problem

[wishbone]

Hi,

I've recently bought a clarke 151TE which came with a problem.

Without the trigger pressed If I measure from the tip to the earth lead with a voltmeter it shows about 35V. If I then press the trigger I get the expected voltage from the lowest setting to highest (16v to 35v) (ish)

The problem reported was that the wire kept on welding itself to the tip or the swan neck liner etc , which seems to tally with having full power without having the trigger pressed.

Can anyone point me in the right direction as to what I should check next ?

I've taken the cover off and cannot find any loose connections, or see any obvious burnt components on the PCB.

Thanks for any help,
Rob.

(I have a working 150te for spare parts if need be)

 

[madkayaker]

Check the harness for damaged wire, rubbish in switch or stuck relay on PCIPCI

 

[wishbone]

Check the harness for damaged wire, rubbish in switch or stuck relay on PCIPCI

Thanks, will have a look at the switches tomorrow eve. The inside looks pretty new and tidy, but I'll unclip all the cable ties and check. Whats the PCIPCI ? - PCB?

Rob.

 

[madkayaker]

Sorry auto correct had a blond moment. Yes PCB

 

[rtbcomp]

Check that the feed assembly, especially the rollers, are isolated from the welding return. For the wire to weld itself to the swan-neck or liner &c there must be a path for the current to flow, but those components and the wire should be at the same potential.

The 35v you're measuring with the trigger released may be from the control PCB. Is it AC or DC? I suspect that is not a fault condition.

 

[wishbone]

Will do - I measured on DC on my multimeter. I haven't tried to weld with this yet, but the seller said it welded itself up as soon as he started welding. I took the gun apart this evening and the swan neck was in pieces and the wire is stuck fast. I have a spare liner etc that I can fit tomorrow to get it all 'right' but don't want to ruin it by trying to weld with it.

Thanks for the input.

 

[rtbcomp]

I'm re-drawing the wiring diagram to reflect the circuit - it looks like there should be a voltage at the tip from the small transformer on the PCB. I'll post it once I'm happy I've got it right. You can download the manual from here

http://www.clarkeservice.co.uk/product_manuals/mig_welders.shtml

 

[rtbcomp]

Here you go



The PCB transformer will put a voltage between POS & NEG via the motor and the two power rectifier diodes.

 

[wishbone]

Rtbcomp,

The circuit diagram you've posted is not the same as the one in the manual ? There's 2 more diodes in the rectifier bit on the 151te diagram.

Think yours is the 110en model.

 

[rtbcomp]

That's what I thought, but the download for the 151is the same file as the 110.

That said, the salient points look the same

 

[wishbone]

Thanks, will look properly tonight.

Before leaving this morning I measured the voltage on my older working 150te and when the trigger isn't pressed it's showing 12v between the tip and the earth clamp.

The rectifier on the 151te is showing approx 20V between each pair of plates, with 40 odd between the big torch connecter and the earth, so I'm assuming the rectifier is working properly.

I'll have to take the PCB out to check it properly tonight.

Rob.

 

[wishbone]

The PCB looks perfect apart from the relay. The relay is working - when the trigger is pulled the relay contacts move together and the motor starts running. However, it is also sparking between the contacts when it does this, and the clear plastic box it is in is slightly blackened near it.

 

[shenion]

It may just be a bleed over voltage to the tip. Basically everything would be floating and a high-impedance will just pick up any small leakage. There is 12V (or more) in the torch lead that the trigger connects to.

If it does not arc with the trigger off, I'd not worry about it.

 

[wishbone]

I'm waiting for a delivery of wire and a new liner so will check if it's arcing without the trigger pulled when it arrives. I'm assuming it will..

Just cleaned out the old liner - was 0.6mm with a 0.8 tip. Surely that wouldn't cause all this ?

 

[the snooper]

I would be checking if there was 230v to the welding transformer without trigger pressed, it should be 0v, if there is power trace where its coming from, someone may have move wires around

 

[shenion]

I doubt there is welding voltage as the wire feed is powered from the welding output. If the main transformer was on all the time, the wire feed would be too.

 

[wishbone]

Thanks everyboby for the help. I think I owe you all an apology for wasting your time as I have just stripped out the torch and fitted a new liner / swan neck liner / swan neck / tip and it's working perfectly. there is still the voltage 'floating' between the tip and earth but the wire does not arc without using the trigger.

I can only assume that the previous owner had problems setting up the torch properly or had the wire tension too low causing the wire to slip and burn back to the tip and sticking ? (maybe burning back inside the tip as it was 0.6 wire on a 0.8 tip ?) Thinking about it he may have been using the 0.8 roller as well..

I'll keep hold of my old 150te for a while until I can be sure this 151te is reliable.

At least I know a lot more about how this welder works than I did a couple of weeks ago..

Cheers again all,
Rob.

 

[Robotstar5]

Thanks for letting us know you got it sorted, now get