Confirmation on what I think I need to look at please

[hunter27]

Yesterday I was using my Cebora Boxer 175 mig trying to weld nuts onto stuck locking wheel nuts for a friend. I noticed the gas was still flowing without the trigger being operated and there was also a small voltage at the wire all the time but the wire feed wasn't running, other than that the welder worked fine. Today I stripped down the welder for a look and everything is working normally again.
I am sure I have read on here about this being caused by a sticking relay which may possibly be cleaned?
If this is the case I will try to remove the relay cover on the PCB and cleaning the contacts. I would like confirmation about this before I mess it up completely, and would a sticking relay also send power to the wire?
I have added a picture of the board with what I guess must be the relay.

Many thanks.

 

[zzr1200]

.....Any numbers on the sides of the relay?

 

[gaz1]

you can clean it but its a git getting into them

just buy another relay and swap them over as they are cheap enough to buy and replace

gas could be selenoid or the trigger on the gun itslef it depends on what they use

 

[hunter27]

Picture of side of relay.


Solenoid valve and trigger seem to be working as designed testing with a multimeter. If the trigger is causing the fault I would think the wire feed motor would also run.

 

[eddie49]

The relay on the PCB is very small, there's probably a much larger Contactor in there somewhere.
A full circuit diagram for the Boxer 175 may be available on the Cebora "out of production" website:
https://welding.cebora.it/it/assistenza/articoli-fuori-produzione
To search the list, the data plate should have an "ART" number?

 

[Erie Fred]

Is the gas running afterwards all the time ?
Some have a post flow timer.

As far as small voltage present, my Lincoln 100 will make a spark when you touch the wire to the part, for the next weld,
I suspect filtering caps are still charged.

 

[hunter27]

Eddie49. I was hoping you would see this, The welder is badged as Taskmaster Boxer 175 ART 532 made by Cebora. I looked at your link and their are 2 options mine looks more like the stag186 although it's definitely only 175A
I cannot see another contactor but I don't know much about electrics, is there another contactor in my picture?

The wiring diagram from your link of ART 532 stag





The inside of my welder.



Thanks.

 

[eddie49]

There's not much in there! No contactor, the small relay on the PCB does all the work. It is called RL1 on the diagram, and via connections "A" and "B" it sends AC mains to the welding transformer, and also to the gas valve ( Item 15 ).
The wirefeed motor is powered by the speed controller on the board, separate from the relay.
There are no capacitors across the DC welding output.

Based on the fault you experienced, it is possible that the relay jammed "on", or at least the contacts remained partially conducting. The relay is a Finder Type 45.61 :

Pardon our interruption...

It is an unusual design, with normal pins into the board for the relay operating coil but external push-on tags off to the side for the switched contacts.

 

[Hutcho]

I’d be tempted to swap gas valve - might be sticking - just because the voltage drops off don’t mean it’s working correctly.

 

[hunter27]

Hi eddie49
I have been searching for a replacement Finder 45.61 relay this afternoon. The one you linked to is 12V mine is marked up as 24V. Finder 45.71 24V relays seem to be more common but I am not sure it would work as a substitute?

https://www.digikey.co.uk/en/products/detail/finder-relays-inc/45.71.7.024.0310/15288407?gclsrc=aw.ds&&utm_adgroup=&utm_source=google&utm_medium=cpc&utm_campaign=PMAX%20Shopping_Product_Middle%20Performing&utm_term=&productid=15288407&utm_content=&utm_id=go_cmp-19510050134_adg-_ad-__dev-c_ext-_prd-15288407_sig-Cj0KCQiAoJC-BhCSARIsAPhdfSivxXCEfksn3unn-lBu460_i5mU54ohV8Xt_n8IyetfTKfGP_2wIQMaAkkPEALw_wcB&gad_source=1&gclid=Cj0KCQiAoJC-BhCSARIsAPhdfSivxXCEfksn3unn-lBu460_i5mU54ohV8Xt_n8IyetfTKfGP_2wIQMaAkkPEALw_wcB

 

[hunter27]

I’d be tempted to swap gas valve - might be sticking - just because the voltage drops off don’t mean it’s working correctly.

The gas was leaking out full bore yesterday without the trigger being pressed it was not just slight let-by as I would expect if the valve was faulty. but I will bear this in mind. Thanks

 

[eddie49]

The one you linked to is 12V mine is marked up as 24V.

Well spotted ! Sorry, I missed that !! Yes, the 24 volt Type 45.71 looks identical and should fit.

 

[hunter27]

Well spotted ! Sorry, I missed that !! Yes, the 24 volt Type 45.71 looks identical and should fit.

Brilliant thanks, I will get one ordered.