Sealey 150/5 stopped working no wire feed .

[paul123mig]

Hi all I've just registered on this forum and hopefully someone can help with my welder. It's a sealey mig welder 150/5 had it for 10yrs or so never had any problems. Last week I set it up to do a little job but unfortunately it didn't work.
So when pluged in and turned on the fan runs fine ,however when the trigger is pulled there is nothing, no wire feed no clicks just silent.i have taken the case off the gun and the wire is all connected to the trigger so I'm thinking mabe pcb but would like some input from someone with a bit more experience in this field than I have please

 

[BrokenBiker]

First port of call is to check the trigger switch for continuity. Not uncommon for them to fail on any torch. If that's fine then check for voltage to the motor.

 

[paul123mig]

Hi thanks for your reply. I've taken the gun apart and the trigger switch is just a piece of metal strip with the wire attached to it it just pushes against a metal post when the trigger is pulled sonthat seems ok.ive also chucked the motor with a 12volt battery and it runs fine too.

 

[BrokenBiker]

Hi thanks for your reply. I've taken the gun apart and the trigger switch is just a piece of metal strip with the wire attached to it it just pushes against a metal post when the trigger is pulled sonthat seems ok.ive also chucked the motor with a 12volt battery and it runs fine too.

So, have you checked the switch for continuity? Looking ok and being ok aren't the same thing...there could be a broken wire anywhere along the length of the torch that you won't find without checking continuity at the terminals in the machine.

The motor working from a separate power source Is all well and good, but that doesn't really mean anything except the motor works, it doesn't tell you if it's getting voltage from the welder, assuming the trigger works, when it's requested.

 

[paul123mig]

Hi thanks ,I'm going to buy a multimeter Saturday so will check for continuity at the switch.and go from there .
Thankyou for your help I appreciate it .

 

[BrokenBiker]

you can check continuity with the 12v battery you used on the motor...1 terminal to a switch wire, 2nd switch wire to a 12v bulb, other end of the bulb to the other terminal of the battery...pull the trigger and bulb should light. if not, you got a problem

 

[mike 109444]

Circuit diagram attached. Bee aware there is mains voltage on the pcb.
And welcome to the forum

 

[paul123mig]

Thats great Mike ,thanks very much .

 

[eddie49]

Hello and welcome to the Forum.

Since you do not hear any clicks, the relay on the control board which powers-up the main welding transformer is probably not being enabled. The most common reason for this failure is loss of the auxiliary power source from the potted transformer on the board. The primary coils of these small transformers tend to burn out. This issue can be confirmed by operating the relay manually. With the welder powered off and unplugged, it may be possible to remove the transparent plastic case from the relay. Then plug in and power up, and use an insulated tool to close the contacts of the relay by actuating the armature. The welder may then work, as if you had pressed the torch trigger. With a meter, you could then follow the troubleshooting advice from Mike in Post #7.
The resistance of the primary coil of the small transformer, checked with power off, may be up to 3k Ohms, but it should not open-circuit.

 

[paul123mig]

Hi Eddie thanks for the useful information. Can you let me know which item on the pcb is the potted transformer please.

 

[eddie49]

It is a plastic lump, about 2" square and 1" high, usually grey or black.
However, some models may have a conventional small transformer off-board, fastened to the chassis.

 

[paul123mig]

Ok thanks very much I will have a look as I have the pcb off the welder now

 

[eddie49]

I'm afraid you will not be able to open that black relay to operate it.
If you are confident working on live electrics, you could short the contacts ( e.g. by soldering wires and adding an on/off switch, or jumper across the Live in- and out- terminals i.e. FS1 and FS2 in Mike's diagram ), or wait to measure the transformer primary coil resistance and/or output voltage ( about 12v AC ).

 

[paul123mig]

Ahh ok thanks .mabe I could take a chance and try to locate a black relay and solder it the pcb .
Thanks

 

[eddie49]

The relay has a diagram on it showing the operating coil and the contacts. You can trace the two printed tracks from the contacts and should find the in- and out- terminals for the Live AC mains feed through the relay contacts to the welding transformer.