Miller Welder Problem or Operator Error?

[Markfothebeast]

I received a Miller 150 STL TIG welder from a buddy. The machine was taken out of service and upgraded so it is unknown if it functions properly. I bought a new ground clamp and electrode holder for it. I'm planning to use it for stick/arc welding.

I have a Lincoln MIG I've used for about a year but have been attempting to learn stick on this Miller. Anyhow, when striking the arc, the rod was "sticking". So I turned the amperage up to 105 and it began a smoother strike/start but the arc would wither away after 2-3 seconds. After 3 or 4 attempts the fan kicks on. After 5 minutes of attempting to strike an arc, the power light began to flash. I'm not sure if this is an operator error or a problem with the welder.

I'm welding to clean 12g 1x2 rectangular tube steel. I have the electrode holder in the positive terminal and the ground clamp in the negative. There are 3 modes on the machine with a symbol on each. The 3rd mode down is what the manual appears to show as "Stick Mode". The machine is 120v or 240v and is connected to a dedicated (120v) 20 amp circuit on a 20 amp outlet, with 12/2 wiring, located 6' away from the 100 amp garage main.

I'm wondering if the machine is lacking amperage output? I have an AC clamp meter so I was thinking of testing the AC draw but I do not know if that will give me any clues to the amount of amps it is putting out.

 

[Bobcat753]

That machine is only good up to 90 amps on 120V input. What size rod are you using? For best results you would hook it up to 220V and the machine should work fine.

 

[Markfothebeast]

I thought about that as well. The machine itself has a small diagram on the front showing 20a 120v supporting into the 100 amp range. I've tried 70 amps as well.

The neighbor gave me a few welding rods and they are unlabeled. He had said they'd work with this unit. I'm not sure but I believe the thickness is 1/16"?

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[GaryM909]

I have had one of those machines since 2008 and never had that problem. I have only used it on 110 because I don't have 220 in the garage.

 

[Markfothebeast]

Being a DC machine, I suppose I could test the output for AC current leaking through a faulty rectifier diode. It would definitely cause a drop in output.

 

[Bobcat753]

I would go out and buy some new 7018 in 3/32". Also what size leads are you using? I see you have the DINSE adapters.

 

[Markfothebeast]

Yes. Both are Tweco brand with 2-gauge wire I believe. The Dinse adapters are 50mm to 25mm.

 

[Markfothebeast]

I haven't dug in to the rectifier yet but I did find this.

 

[Markfothebeast]

 

[Bobcat753]

I think you found your problem! That definitely looks bad. Also you can see on the circuit board how it is browned, meaning that sector got HOT!

 

[Markfothebeast]

Are there any schematics available online for this Miller Maxstar 150 STL (or Even STH)?

If anyone is kind enough to point me to the online or PDF schematics I would appreciate it. If these documents are super duper top secret, I guess I'll be spending more time checking over it.

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[DerekV]

Are there any schematics available online for this Miller Maxstar 150 STL (or Even STH)?

If anyone is kind enough to point me to the online or PDF schematics I would appreciate it. If these documents are super duper top secret, I guess I'll be spending more time checking over it.

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Why don't you try giving Miller a call? Their product/technical support is awesome.

 

[Markfothebeast]

I'll do that. For some reason I get the feeling from past experiences that I'll be told to purchase a new board other than receiving schematics. And the board isn't cheap...

I did go to the Miller website and enter the serial number in hopes of finding schematics but all I found were vague PDFs with details that simply point out the wiring.

Here's what I did find; of the 3 15k ceramic resistors (pictured), the first 2 with the burn mark are out of spec. The 3rd was undamaged and reads very close to 15k ohms. #1 reads 11k. #2 reads 13k.

The manual states that 4 flashes of the power LED is possibly an over-voltage condition. It then shuts down the output. I'm not sure if it is related to a transformer issue or a sudden power surge. It looks like it might be on the AC side before the small transformer on the mainboard near the power cable input.

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[Markfothebeast]

Does Miller typically use transformers wrapped with speaker cable and taped on with packaging tape? This sucker is melted through on the speaker wire insulation. A poor choice for something dealing with heat crammed in a small box. It was never modified before as far as i know. The other two transformers look fine. One wire has poor continuity.

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[Bare]

I received a Miller 150 STL TIG welder from a buddy. The machine was taken out of service and upgraded so it is unknown if it functions properly. I bought a new ground clamp and electrode holder for it. I'm planning to use it for stick/arc welding.

I have a Lincoln MIG I've used for about a year but have been attempting to learn stick on this Miller. Anyhow, when striking the arc, the rod was "sticking". So I turned the amperage up to 105 and it began a smoother strike/start but the arc would wither away after 2-3 seconds. After 3 or 4 attempts the fan kicks on. After 5 minutes of attempting to strike an arc, the power light began to flash. I'm not sure if this is an operator error or a problem with the welder.

I'm welding to clean 12g 1x2 rectangular tube steel. I have the electrode holder in the positive terminal and the ground clamp in the negative. There are 3 modes on the machine with a symbol on each. The 3rd mode down is what the manual appears to show as "Stick Mode". The machine is 120v or 240v and is connected to a dedicated (120v) 20 amp circuit on a 20 amp outlet, with 12/2 wiring, located 6' away from the 100 amp garage main.

I'm wondering if the machine is lacking amperage output? I have an AC clamp meter so I was thinking of testing the AC draw but I do not know if that will give me any clues to the amount of amps it is putting out.

Hello. I am having the same problem with Maxstar 150 S Miller welding machine. How did you solve the problem?