Butters AMT 311

[Paul@melkelter]

I would like to thank anyone who has tried to help with the problem I'm having with my welder,everything else on the machine works great apart from the gas solinoidseems to be energised most of the time,I have to keep turning the machine on and off all the time,so I don't waste gas,I've already run one gas bottle off without realising it,and at great cost.it a case of tracing the two gas solinoid wires back as far as possible to find out why they are always live? The only time the gas stops is when I turn the machine off,then as soon as I turn it on the gas is coming through the nozzle constantly. Any one with any ideas, I would be very happy to look at these ideas,any thoughts at all???
Thanking you all in advance. Paul.(very wound up)

 

[eddie49]

This problem was first discussed in another thread:

P

Thread 'Butters AMT 311'

Nov 2, 2025

Hi all,is there any one person on this planet that would have, or access to a circuit board diagram or any form of schematics, so I can try and fault find the problem I'm having. Whenever you turn the welder on the gas starts to come through,and continues to keep coming through until you turn the machine off.while you are using the welder the gas solinoid cuts off and comes back on whenever it feels like it,I've tried looking for information on this machine but can not find a single thing(, and have I tried looking) I would have to say this is the best mig I've ever had.Any ideas would be...

• Paul@melkelter
• Replies: 8
• forum: Butters

In Post #7 of that thread the Forum member @Nix2 asked about the type number of the PCB that might be fitted to your welder, and in Post #9 I supplied a link to a wiring diagram that would apply if the board numbers are "7977339" and "7977999".

Please look for those numbers etched into your board, and also confirm that the operating coils of the gas valve solenoid and the main contactor are labelled as working on 42 volts AC. Then we will know that the diagram does apply to your machine. In that case, disconnect the wire connected to Pin 11 of the printed circuit board - it should be the power feed to the gas valve. If you then switch the machine on and the gas valve is no longer always open, we know that the fault is on the board.

 

[Paul@melkelter]

I have taken a picture of the board i can say the gas solinoid valve is 24v ac,does that help?

 

[Paul@melkelter]

Is there anything specific i need to look at,I'm OK with general electrics and a test meter,everytime I turn the machine on at the switch the gas solinoid has 24vac on it

 

[eddie49]

From your photo, the board does have those two numbers on it, so the wiring diagram on Page 2 of the Italian website should apply:

https://www.re-elettronica.it/files/acatalog1/download/re419.pdf

Regarding the AC voltage on the operating coils, the description of the board does actually say "Single supply voltage 24Vac or 42Vac" so I guess your version is 24 volts.
It is hard to understand why only the gas valve is being set permanently "live", since it is generally supposed to be enabled in parallel with the main contactor. The two black relays ( which you said have been replaced ) switch the gas valve and the contactor, and it appears that they are being driven differently by the electronics on the board.

Does your welder have any controls for burnback or gas pre- or post-flow?

If you power up the welder without the Eurotorch connected, do you still get the same gas valve fault?

 

[Paul@melkelter]

Yes it is exactly the same when you disconnect the euro torch,the one thing I don't understand is number 5 pin on the board has no wire to it and also at the other end of the pins there is 1 pin on the board that is not connected to anything

 

[Paul@melkelter]

Turned on then turned off and still always 25vac when on,it can't make any sense of it

 

[eddie49]

As shown in the diagram, Pin 5 is not used. At the other end, Pin 20 could be used for a "Test Motor Switch" - in other words, a button to inch the wire, used to feed new wire up to the end of the torch. If that pin is blank, then your machine does not have this option.

I do not have a circuit diagram of the board itself. Perhaps @Nix2 does?
Remote faultfinding at component level without a diagram, just using photos of both sides of the board, can be done, but it is not easy!
It would involve tracing the tracks from the coils of the two black relays and finding what components control them and why they differ.

New boards are available from Weldequip for £189.30 :

Butters AMT MIG Welder Printed Circuit Boards - Weldequip

Tec-Arc in York ( Les Ford ) probably would be able to repair your own board.