Miller Spectrum 875 Auto-Line Internal Torch Wiring

Does anybody on here run a Miller 875 on their Langmuir table? I am wondering how you have your torch-fire wired up. I have mine spliced into the switch wires from the torch, but this isn’t the “proper” way. Miller shows two spots to wire into. One with 24v live terminals, and one with cold terminals. RMT1 and RMT2. The manual shows how to hook up a torch fire with the factory automation kit installed. Mine does not have the factory kit installed.

Using the spliced method, the torch has a second or so of pre-flow before starting the arc. Making it very difficult to program the right pierce delay times. I’m hoping that tying into the factory location, the torch will fire sooner?

I had a 375 Extreme running on it previously, but the 375 would fire right away when commanded to do so by mach3.

Any productive help would be appreciated!


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Ok, seems nobody had any input, so ill leave this here for the future if anybody needs it. NOTE: this is an ICE-60T torch on a Miller Spectrum 875 Auto-Line

There are two ways for the Langmuir to fire the torch on the Miller 875.

The easiest way is to tap into the wire labelled 13 and the wire labelled 14, connect to the wires from the table, in any order. Done (Notice wire and tap location in the bottom right corner of image)

The PROPER way, according to Miller, when using a handheld torch in place of the miller machine torch, is to remove the trigger micro-switch in the torch - Install a 23.7 K Ohm (24K) resistor into the connector.

Then get one of these square connector housings and pin for about $4 and crimp terminals onto two wires and install in the bottom two positions. (Position 1 & 2, labelled on the board for RMT1)
Note in the picture the two black wires installed into the connector and inserted into RMT1.

Then the two wires from the connector get routed to the wires from the table, and you’re done.

Now, after trying and testing both methods, I have resorted back to the basic wiretap on wires 13 and 14, so I could keep the trigger switch installed so we can use the torch by hand if needed. Pre-flow is the same with both methods.

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Thank you for the info i have an 875 and a machine torch and am still in set up and wiring mode! Have you been pleased with the 875 so far?

Mclovin, I opted for the Miller automation kit, should i plug its harness into RMT1? I will be using a machine torch.

Did your system fire the torch with the machine torch and plugging into rmt 1? I am having issues with mine wanting momentary switching to fire and not a closed circuit like the Langmuir provides…

Craigg, Would you believe, I still haven’t put my machine together yet? It’s all there, just don’t ever seem to find the time. Sorry I could be of no help to you.

any update on this? were having an issue with “cutting voltage not detected” torch will not fire…

I can’t tell where your raw voltage connections are terminated inside the 875 but that is an insanely long amount of cable for raw wire voltage DC. Ideally you would have the high voltage side of the vim with a shorter cable as possible even mounting the vim box on your plasma cutter and then extending the cable if need be after it’s gone through the vim.

here’s a picture where the raw voltage is terminated

do you havbe any more pictures of your wiring setup at this point? because clearly yours works. lol
i can pass the voltage test but the torch will NOT fire

Are you running the machine torch?

The RC48 connecter is the raw voltage signal on your miller ( I have a 375 )

has the torch ever fired ?


it has not ever worked as it should.

i can pass the voltage test, when it comes to “torch fire” test… i click fire, nothing happens… when i hit reset the torch fires for a second then shuts off.

That is some honking big antenna, I mean, torch voltage cable you’ve got there! Cut that down to about 4 feet or less and you’ll probably have a much more stable torch sensor.


torch sensor? so that cable tells the torch to fire? i will cut it down. your talking the one that goes to the VIM box

No, the cable to the VIM box ‘senses’ the torch voltage from the connection to the Plasma Cutter. You want to keep that cable as short as possible and as far away from the Torch and Work cables as possible.


still have issue… torch will not fire when test, i hear the relay clicking when i hit torch fire… ITS ALMOST LIKE ITS A 2T 4T issue miller 875 doesnt have this function

i was able to make a straight cut by manipulating the G code… :frowning:

G0X0. Y0.

this is not ideal. im stumped and super annoyed at this point lol