Help with miller trailblazer 251-NT

[therrera]

Hi all,

can someone tell me if the Trailblazer 251-NT has a built in contactor? I recently purchased one that came with a Miller high frequency box (hf251-d) but I don't hear the contactor kicking in and the tig torch I have connected to the box is hot regardless of how the remote switch on the torch is set to.

I have never welded with this machine and would like to know if someone can tell me what the procedure is. It stick welds just fine. When I put it in TIG mode the torch wants to start but it seems to lack the HF to sustain the arc so it just sparks. I am used to an on and off switch mounted on a tig torch that initiates the arc when the contactor kicks in.

My old unit had a miller hf box like this one but has a contactor built into it. The one that came with the trailblazer does not have a contactor.

Anyone?


Thanks,

Tony

PS: I am going to download the manual for my unit and see what the docs tell me.

[duaneb55]

Tony,

The TB 251-NT (as with other TB models) don't have a mechanical "contactor" but rather the control board turns weld output on and off by turning the weld output rotor field current on and off.

To turn output off or to control remotely, the toggle switch above the A/V toggle next to the 14-pin receptacle needs to set to remote (14-pin symbol).

[therrera]

Hi Duaneb55,

thanks for the reply. I was able to compare the HF unit with my old one that I just pulled out of my rig and see that the hf sparks are present whenever it is put in local mode. The "new" one doesn't telling me there is something wrong with it.

I called Miller tech support and they tech told me that there are several areas where the unit could be failing and gave me a list of check points (a relay, a transformer and switch). A nice plus is that he said they will walk me through the troubleshooting process over the phone while I have it on the bench taken apart.

I swapped out the "new" one with my old one and it is working fine now. I see that the model I have, my old one, had an externally mounted contactor and the "new" one doesn't. However I see that it is just a design change as the contactor is still present. It through me off, that's why I posted my question.

Thanks and I have another question which I will post next.

Tony

[therrera]

I was practicing with my "new" (to me) trailblazer to get a feel for it as I have to go out today and do a service call on a broken transmission case.

I was reading the docs on it and it said when using the remote all switches should be set to remote (14) in the diagrams. I did so and fired it up to test with a scrap piece of aluminum and was shocked to discover that I could barely start a puddle on a piece of 1/4" plate. I was horrified as one of the primary roles of my welding services is field welding aluminum. In fact I was barely able to carry a puddle on some 1/8" aluminum plate.

I had visions of a horrible mistake on my part and kicked myself (mentally) for buying it without testing ALL the functions. I was in a state of trance over what a good deal it was and how low the hours were on it that I wasn't thorough at all.

So I went out today and started trying everything I could think of to see if it would make a difference. I cleaned all contacts, including the remote pins, checked for loose cables and so on.

One of my last efforts was to play with the switches on the panel and set them both to panel instead of remote. Low and behold I got full amperage and practically burned a hole through that 1/4" plate.

So my question is: Is that the correct setup for the switches which means the docs are wrong or is it assumed that the remote is coming from a wire feeder and not through a hf box like I am?

Regardless I almost fell to my knees and prayed when it got full power after playing with it a while. I had these horrible visions of having to pull it out and reinstall my old AEAD200LE and undo all the fab work I had just done to get it mounted and reorganize my equipment to make it fit again.

Thanks,

Tony

[therrera]

Hi again,

sorry, another question:

My "new" trailblazer came with a torch mounted amperage control switch. It has a rotary variable switch. I have never used a variable remote before. I was wondering if these are easy to use as opposed to my old setup which was an on-off affair?

Since I had to install my old HF unit on the trailblazer as the one that came with it was bad, I have my old on-off torch installed on it. I am considering switching it out with the new one that has the variable remote.

I am somewhat reluctant as I already know and am familiar with using the on-off method to control my puddle. The remote seemed a little clumsy by comparison. Would you recommend practicing with it before taking it out or is its operation pretty natural so just take the plunge?

Any thoughts?

Thanks,

Tony

[therrera]

Hi,

I just figured it out. The reason I wasn't getting full amperage when I tested the trailblazer with the HF unit was because I was using an on-off switch. Since there is no variable adjustment on it, I need to base the heat on how the panel is set for. Therefore I need to make sure the switches are in panel position and NOT remote.

However when using a variable remote, the switch MUST be in remote mode in order to control the amperage. I just switched torches with the one that was on the "new" HF box and has a variable remote switch and it worked fine with the switches in remote mode.

I get it now. duh....... I am happy once again. How simple life can be.


Thanks,

Tony