Clarke 110en turbo wire feed stuck at full speed

[pieandapint]

Hi folks,

Unfortunately I had a bit of misfortune the other night using the above welder. I was in the process of setting up the machine by feeding the wire down the liner when all of a sudden there were sparks inside the case. What had happened is the wire had jammed and gone into the case causing a short.

Now the wire feeds at full speed only.

I've had a look around the forum and tried replaceing the thyristor with a tyn608 (turns out the original was a tyn408 - does it matter?)

Anyway, the problem still exists. Can anybody please point me in the right direction?

Cheers
Dave

Oh, and hello! :0)

 

[mike 109444]

Note there is another small transistor on the pcb that might be worth replacing along with fitting correct tyn device (you might even find the original device is not duff! and could be refitted as fault did not change)
And welcome BTW

 

[pieandapint]

Note there is another small transistor on the pcb that might be worth replacing along with fitting correct tyn device (you might even find the original device is not duff! and could be refitted as fault did not change)
And welcome BTW

Which transistor is that? (The NPN MPSA42?) Could the potentiometer have gone south?

Cheers
Dave

 

[mike 109444]

Not sure what the number is on the tranny. It's possible the pot has gone but would normally expect a pot to go open circuit. Most if not all other parts on pcb would be unlikely to fail in such a way that they cause the fault.
I am assuming it's this pcb type ?

 

[the snooper]

Hi folks,

Unfortunately I had a bit of misfortune the other night using the above welder. I was in the process of setting up the machine by feeding the wire down the liner when all of a sudden there were sparks inside the case. What had happened is the wire had jammed and gone into the case causing a short.

Now the wire feeds at full speed only.

I've had a look around the forum and tried replaceing the thyristor with a tyn608 (turns out the original was a tyn408 - does it matter?)

Anyway, the problem still exists. Can anybody please point me in the right direction?

Cheers
Dave

Oh, and hello! :0)

Tyn 408 has 400v rating 608 has 600v rating

 

[the snooper]

I'm with Mike I doubt it's the pot, as you have replaced the thyristor I'd change the driver (small transistor)

 

[pieandapint]

Cheers guys, got the transistor ordered so I'll try that and let you know.

 

[Steve928]

Hi folks,

I was in the process of setting up the machine by feeding the wire down the liner when all of a sudden there were sparks inside the case. What had happened is the wire had jammed and gone into the case causing a short.

Sounds like you were you using the motor to feed a new wire?
I may have got the wrong end of the stick but personally I would always feed the wire by hand with the machine switched off.

 

[Steve928]

Really? I'd never be bothered to hand feed it.

Take out the contact tip, start the first couple of inches by hand then let the feed motor do what it was built to do - feed wire.

The removal of the tip is so the end of the wire doesn't snag and cause a birdsnest...

You're quite right, I've just checked the manual and it says to do exactly what you're doing.
I must be over-cautious but prefer to feed it gently through to avoid any snags particularly at the bend in the swan neck.

 

[pieandapint]

Good news! Changed the transistor NPN MPSA42 (12 for £1.79 off of eBay) and wire speed is functioning again.

Thanks for all your help
Dave

 

[mr migwire]

thanks for the update dave, its nice to see a thread conclude...

 

[pieandapint]

No worries, for anybody else suffering this problem here's an image showing the transistor that needed replacing. Also a board shot incase it comes in useful.

Thanks again.
Dave

 

[the snooper]

I'd consider a clip on heatsink for that...

No need for a heatsink they don't get hot enough to burn themselves out the op had an accident in that mig wire made contact with the pcb

 

[the snooper]

It just looks naked and lonely

It is lonely it's isolated from higher voltages I'll get my coat