Clarke 150en wire feed

[ajm291]

Hello,

I recently purchased a "preowned but never used" Clarke 150en turbo welder. After installing a male plug on the welder power cord and connecting to 240VAC, the wire feed isn't working. My assessment on this seems to be an electrical issue with the drive circuit. I've been reading posts on this topic on this forum and tried a few things, but now need some help digging deeper into this issue.

When I power up the welder, the fan kicks on.
When I pull the trigger on the torch, the relay on the wire speed PCB closes. I have a gas bottle connected and I get gas flow out of the torch.
I don't seem to be getting voltage to the wire feed motor.
I removed the wire feed motor assembly and connected to a variable bench power supply. The motor spins via external power so that's not the issue.
I replaced the MOSFET on the PCB as this seemed to be a common issue/repair. My PCB is an older revision so it has a MOSFET and not an SCR (upper left in image below riveted to heatsink)

At this point I'm stuck and need some guidance on what to look at next. There's a small transformer on the wire feed PCB. Maybe this could be the source of my issue, but I recall reading that if this isn't working, the relay won't close. In my case the relay is closing when the trigger is pulled on the torch.

Below is a pic of the PCB in question. I grabbed this image from an ebay listing (unfortunately this PCB is sold out) but my PCB is similar.

2 pins (pins 3 & 4) on the white 5 pin connector go to wire feed motor.

I was able to find a post that contains pics of the 150EN user manual.
Below is a image of the schematic from this manual for the 150EN model.

I'm looking for and open to suggestions on what to do next. Appreciate any guidance on this!

 

[a111r]

Welcome.
Are you getting any OCV at all, when pressing the trigger? That's what powers the motor.

They should range from 18v dc to 30 vdc for this machine.

 

[Bobbes]

I don't believe that an older board has a Mosfet instead a SCR. What is the typenumber of the old component

 

[ajm291]

Welcome.
Are you getting any OCV at all, when pressing the trigger? That's what powers the motor.

They should range from 18v dc to 30 vdc for this machine.

I just took the OCV measurements from torch tip to ground lead.
Here are the results:

MIN 1: 29.74
MIN 2: 33.31
MIN 3: 37.88

MAX 1: 36.62
MAX 2: 42.21
MAX 3: 49.20

 

[ajm291]

I don't believe that an older board has a Mosfet instead a SCR. What is the typenumber of the old component

The part is IRF640

Here is a link to a post that's related to this topic:

Archived Link

I replaced this IRF640 with this part from amazon:

Amazon link

 

[DSR]

Hi @ajm291, that all looks good and you have covered all the major issues. Getting gas out is good as well. Can you try swinging the wire speed control knob from end to end with the trigger pressed. I'd also check the 5W 470 ohm resistor - it's unlikely to be burned out (would need about 50V to push more than 5W through it...) but they do sometimes go out.

Have a look at all the components with a Loupe and see if you can see any that are broken - especially the transistors. Do the same for both sides of the board - check each soldered joint and look for crystalline or grey dry joints. On a related note, are there any components on the bottom of the board ?

If you are feeling adventurous, you could join the drain and source pins of the MOSFET together and see if the motor runs flat out. D & S are the middle pin and the top pin respectively in your photo.

Can you post pictures of your board, not one off Ebay - you say yours is similar but that picture doesn't look like it is a MOSFET based board - I'd expect a few more components as the drive and control methods are different between SCR (Thyristor) and MOSFETS.

If you have replaced the MOSFET bolt it down if it isn't. The tab is connected to the middle pin (Drain) and it could have a pad on the circuit board that needs to be connected to the tab.

 

[ajm291]

Can you try swinging the wire speed control knob from end to end with the trigger pressed.

I tried this without success. still nothing from wire feed motor.

I'd also check the 5W 470 ohm resistor

I measured this with the DMM and read 460 ohms

especially the transistors

Maybe I should just replace these? It looks like there are 3 of them (assuming I'm looking at the correct component) that are the same part number on the PCB.

Can you post pictures of your board

Sure. Pics of both top and bottom of PCB.

If you have replaced the MOSFET bolt it down if it isn't.

I drilled out the rivet and replaced with a bolt. I used thermal compound paste to ensure good thermal flow.

 

[a111r]

"When I power up the welder, the fan kicks on".
That's normal, it's wired direct to the input.

"When I pull the trigger on the torch, the relay on the wire speed PCB closes. I have a gas bottle connected and I get gas flow out of the torch".
That's also normal, the gas valve is mechanical and is in the torch. The PCB seems to be working.

"Here are the results":

MIN 1: 29.74
MIN 2: 33.31
MIN 3: 37.88

MAX 1: 36.62
MAX 2: 42.21
MAX 3: 49.20

Consistent, but they are much too high. It is odd that your feed motor is not screaming!
Post up some photos of the internals. Anyone been inside it before..?
As it seems like some of the primary has got 'removed' by wiring. Fewer turns = higher output.

With these, quite often, the rocker switches go bad, or the various bolted / crimped connections go high resistance, reducing arc power to a glow.

 

[ajm291]

So, I took an $85.00 (total with tax and S/H) chance on a newer model wire speed PCB listed on ebay.

Link

I swapped this PCB into the welder 10 minutes ago today and it works!

There are two extra connectors on this newer PCB, JA & JB. I simply made a jumper wire to connect these terminals together and everything seems to be working.

I'd still like to troubleshoot the original PCB to get it working again.

We can trust the welder as it's laying beads now so I'm open to swapping components on the original PCB and testing it out in the welder until it's functional again.

 

[DSR]

So, I took an $85.00 (total with tax and S/H) chance on a newer model wire speed PCB listed on ebay.

I'd still like to troubleshoot the original PCB to get it working again.

We can trust the welder as it's laying beads now so I'm open to swapping components on the original PCB and testing it out in the welder until it's functional again.

Good news At least the problem has solved and you have a known knackered board.

The problem with your original board is more than likely one of the semiconductors - including the MOSFET - they can be susceptible to static and should be handled with care when being installed. Looking at the PCB top and bottom, it all looks fine but have a look at Q5 (topright in your photo) - it could just be a bad photo but the case looks to be deformed on the right hand side..