Attn: CRUIZER! Millermatic 175 dead (Power to welder-No fan-No Gas-No Arc)

[blue devil]

So the other day my Millermatic 175, which was bought around 2003-2004, die on me. I had just finished a few beads and set the torch down on the table as I setup for a few more. After a minute or two I heard a loud fuse style pop noise behind me. Checked the house fuse (OK), checked wall power (OK), checked for power into welder (OK), but the welder itself had no reaction to anything. No fan, no feed motor, no gas output, no arc, nothing.

I came across the following thread in which CRUIZER (hopefully he sees my thread) responded with the following comment:

http://www.millerwelds.com/resources...reply&p=267467

There is a transformer internal to the fan motor that supplys 24Vac for the rest of the system, it may be pooched. however if it is pooched, there is no protection on the circuit board, so two traces are generally blown off it. These 2 traces pass from one side of the board to the other and simple to repair with a couple of 24 gage wires soldered from one side to the other

Looking at my board, everything visually checked out, but as mentioned the two traces were blown off. Now I have done a good amount of prototype circuit board work and I have also made several complete wiring harnesses for racecars, so this task does not intimidate me.

My question to CRUIZER and others:
I see exactly which wires to replace, their beginning/ends, I have the proper wire guages, and I have all of the proper tools. Based on your experience, would your advice be:

1. Solder in mentioned wires
2. Replace the $36 fan motor unit: P/N 196 064 . . MOTOR, fan (230 VAC model)
3. Test welder by trying to power it up.

What are the other potentially damaged items? I have no problem taking my chances, spending $36, and a few hours to possibly repair the unit before throwing down $1000 or more for a new unit. I just wanted to know if this same scenario killed any other components that I will need to replace?

Thanks!
Jerry

[duaneb55]

Got it done yet?

[blue devil]

No, I havent even ordered the fan motor. I wanted to make sure I was understanding his statement clearly and was looking for any further advice or knowledge before doing so.

I figure if he recommends a new fan and two new traces, worst case scenario I am out $40. Its a cheap price I am willing to pay to get the welder functional so it can live another day... and buy me more time to save for a new MM211

[Miller Kevin]

Blue Devil,

I would suggest checking the fan motor with an ohm meter to see if it has failed. It is pretty easy to check, unplug the fan motor and ohm across the 2 white wires, you should see about 5 ohms and across the black leads you should see about 50 ohms.

[blue devil]

Okay I will check with my multimeter tonight and post the results. Are these resistance values indicative of a good motor or bad? I'm assuming good. What is the acceptable tolerance (+\- ? ohm) on these values?

[Miller Kevin]

Those would be for a good motor, they should be pretty close to that probably +/- 1 ohm on the 5 ohm reading and +/- 5 on the 50 ohm reading.

[blue devil]

I always test three individual times to rule out my own error...

Black: 48.3, 48.6, & 48.7 ohm
White: 2.8, 2.7, & 2.9 ohm

Im guessing it's bad... Which is good as last night I wen ahead and ordered the $40 part.

[Miller Kevin]

From your readings I would say that the fan motor is ok. The 2.9 ohms is a little low but typically if the fan motor fails you would see a dead short or an open there. Take a reading across the gas valve to see if it is shorted.

[cruizer]

No, I havent even ordered the fan motor. I wanted to make sure I was understanding his statement clearly and was looking for any further advice or knowledge before doing so.

I figure if he recommends a new fan and two new traces, worst case scenario I am out $40. Its a cheap price I am willing to pay to get the welder functional so it can live another day... and buy me more time to save for a new MM211

Fix the board, replace the fan/transformer motor, all should be ok.

[blue devil]

I will check the resistance across the gas solenoid. Depending on results I'll replace the fan motor with the new one that came in yesterday ($40 for preventative maintenance) and then rewire the board as I know I have a ton of 20-24 gauge wire from one of my last projects(scratch built track car).

Ill report back the (hopefully) positive results.

Cruizer, any idea what kind of amperage these traces are rated for? I'm trying to work in some type of preventative measure for the future. Thinking along the lines of a amperage regulator as the board probably already has a voltage regulator at the input. Just the engineering mindset thinking out loud...

[Meltedmetal]

Fuses??

[blue devil]

So I finally got around to replacing the fan and repairing/replacing the traces with 22ga solid core and nice clean solder points.

Still nothing... No fan, no wire, no gas... Nothing.
- I have (confirmed) 240v coming into welder
- The board has 120v in several locations
- I checked both poles on the main switch and they checked out OK (I have 240v model)
- Checked the GFI style breaker on the back and its OK (obviously if board has power too)
- no other visual irregularities on the board to my knowledge, but most electrical failures cannot be visually checked.

I will do a search for the diagram and try to track down the weak link, but I figured I would post up anyways. Anyone have a link to the 240v model diagram?

Other thoughts?

[Miller Kevin]

Did you check to see if you had 230 volts to the fan motor on the 2 black wires?

[blue devil]

I will check that tonight and post back up. Where do the two black wires going to the fan motor originate from? If these do not have 230v, what are the potential failure points between the 230v main power into the case and the black wires at the fan besides the main switch?

Did you check to see if you had 230 volts to the fan motor on the 2 black wires?

[Miller Kevin]

The 2 black leads are fed from the control board, RC1 pins 1 and 5. If the switch is good the only other thing that could interupt the power is an open trace on the board itself.