Clarke 90EN switch broken

[learningtoweld]

Hi All, I am new to welding. I have been given a Clarke 90EN. My question is this the switch has 5 pins, (RED IN, / BLUE IN from the plug ) RED OUT, BLUE OUT to the circuit board. But a brown wire at the bottom of the switch goes to the circuit board (what is this wire please) the wire diagram says PE is this an earth ?
I have a 4 pin new 240v switch but need 5 pins like the old one. Any info please.
Thank you.

 

[angellonewolf]

not that i can realy help that much but as ive not got the same unit as your self

as its brown id expect it to be live but wait till you get more info from someone confrms as a question is the switch an illuminated switch ? could that extra wire be for the illuminated feed for overheating ?

just throwing this out there

 

[bourbon]

Did you get the new switch from Machine Mart? If so, give their technical guys a call, They are very helpful?

 

[learningtoweld]

Hi, thanks for that, you may have something there about the " live " because when the switch is off its dead, when the switch is on the live and the brown go live.
The odd thing is though, when the switch is disconnected the brown is not live when the switch is thrown. acording to my multimeter anyway. Thanks again for your time.

 

[learningtoweld]

Did you get the new switch from Machine Mart? If so, give their technical guys a call, They are very helpful?

Hi, no its just a new one I had in my drawer.
It only has 4 pins, the original has 5.
Thanks for your time.

 

[learningtoweld]

Oh and the pin 5 wire is dark brown. The live is a lighter brown.

 

[learningtoweld]

This is the original Clarke switch with 5 pins.
My switch has 4 pins.

 

[eddie49]

The answer from angellonewolf in post #2 is correct - the fifth pin is a connection to the "Overheated" indicator bulb.

Here on page 29 is the circuit diagram of the Clarke 90EN:

https://www.clarkeservice.co.uk/manuals/mig_welders/MIG90EN-151EN_rev5.pdf

It shows that the double-pole On/Off switch has 5 pins. That is because it contains a bulb - probably a neon - with one end connected to the Live. The other end of the bulb is the 5th pin.
The small encapsulated transformer on the printed circuit board gets it's actual Live feed via a thermal cutout switch. If the machine overheats and that cutout opens, the small transformer loses power and the machine switches off. However, there will be a weak current from the Live at the switch via the bulb into the transformer, not enough to run the transformer but enough to light the bulb and indicate the machine has overheated.

With your new switch having only 4 terminals, you will only be able to connect L & N in and out. If it is an illuminated switch, the bulb will show "Power On". In the event of an overheat, the machine will still switch itself off, but you won't know the reason.

 

[DSR]

I joined the forum so I could answer this question

The switch is pretty special and that explains why it's currently unavailable.

Normally the switches are four pins - DPST (Double Pole Single Throw) and there is a neon bulb and series resistor wired across one side of the switch so that when you close the switch, the power goes to the neon and it lights up to show you there is power on. Generally if you put the live mains to the wrong side of the switch, the neon will be permanently on when there is power.

I had a look at the manual for the 90EN and that shows that the neon is only connected to one of the poles on the switch and the other side of the neon goes to the fifth terminal. Following the circuit through, the neon is only supplied power via the fifth terminal when the thermal overheat switch opens. When the welder overheats, the thermal switch opens and cuts power to the main transformer until it cools down. The neon light is wired in such a manner that when the thermal switch opens, it has a circuit path to the neutral line via the controller transformer and so lights up.

That's all the fifth terminal is for - it provides a connection point for the neon light.

You can quite easily leave the wire off and it won't affect the workings of the welder, when it overheats, it will still shut down, you just won't have a light on in the switch telling you its overheated.

You could add another neon indicator to the welder and wire it up to replace the one on the switch if you are desperately in need of it - personally, I'd not bother.

The switch you have will be OK to replace the original but you will have to modify the cables by cutting the ends off and replacing the eyelet terminals with 1/4" crimped spades. You will have an illuminated switch when powers on but no indication of thermal overload when it stops.

Kudos to Clarke for supplying a wiring diagram.

 

[learningtoweld]

Wow chaps,
your explanation was great, very clear. I totally understand now.
Thank you so much for your time in answering my thread.
This has been one of the best forums that I have joined.
10/10.
Thanks again chaps. (Wink)

 

[DSR]

The answer from angellonewolf in post #2 is correct - the fifth pin is a connection to the "Overheated" indicator bulb.

Here on page 29 is the circuit diagram of the Clarke 90EN:

https://www.clarkeservice.co.uk/manuals/mig_welders/MIG90EN-151EN_rev5.pdf

It shows that the double-pole On/Off switch has 5 pins. That is because it contains a bulb - probably a neon - with one end connected to the Live. The other end of the bulb is the 5th pin.
The small encapsulated transformer on the printed circuit board gets it's actual Live feed via a thermal cutout switch. If the machine overheats and that cutout opens, the small transformer loses power and the machine switches off. However, there will be a weak current from the Live at the switch via the bulb into the transformer, not enough to run the transformer but enough to light the bulb and indicate the machine has overheated.

With your new switch having only 4 terminals, you will only be able to connect L & N in and out. If it is an illuminated switch, the bulb will show "Power On". In the event of an overheat, the machine will still switch itself off, but you won't know the reason.

Like buses - two answers turn up at once

 

[bourbon]

And a thank you and welcome to @DSR. For a comprehensive answer to the question.

 

[a111r]

I might well have a spare Clarke one. I will check.

 

[learningtoweld]

Oh great, if you have that would be great.
Thanks

 

[a111r]

Yep, found one. I knew it would come in handy one day...

 

[learningtoweld]

Thanks for the offer but I have just purchased one from Clarke.co.uk.
I found the part number and ordered it.
Thanks anyway for your time looking for it.
Stay Safe