millermatic 185 overheating

[Oldgrandad]

I have an old millermatic 185 in my shop. We've been over using it for about 12 years now, about 4 months ago it started shutting itself down after about 2 hours. It cools down for about 1/2 hour then starts itself back up and is ready for more. A miller rep. was by my shop last week and told me that there is a thermal resistor on the circuit board that can get tired and if I replaced it the machine would be back to its old glory. Can anyone tell me which resistor that is before I tear the thing apart, can't afford the mig to be down

[aametalmaster]

I am sorry to read that. In my opinion that is the best machine Miller ever made. I have a 1999 version. Have you blown the dust out?...Bob

[Oldgrandad]

Yes, blew it out 6 months ago when I changed the contactor then again a few weeks into the overheating problem. I agree this machine runs so smooth its a pleasure to weld with.

[aametalmaster]

And you run the welder for 2 hours straight. I missed that part. It isn't a 100% duty cycle machine. I kinda have abused mine but never 2 hours...Bob

[Oldgrandad]

It's not 2 hours continuous, the last job it was used on was building an 18' truck bed, weld 4" move down a few rails run another 4" and so on, if i had to guess its probably about 60% duty cycle usage which is pushing the limits of that machine. The rails are 4" channel welded to the outer frame which is 3/16" thick steel. The welder has been used like this for over a decade and until recently didn't seem to mind. That's why I've got a millermatic 250 an

[Oldgrandad]

and a lincoln 256 but i really like my little 185 and want to make her all better

[H80N]

It's not 2 hours continuous, the last job it was used on was building an 18' truck bed, weld 4" move down a few rails run another 4" and so on, if i had to guess its probably about 60% duty cycle usage which is pushing the limits of that machine. The rails are 4" channel welded to the outer frame which is 3/16" thick steel. The welder has been used like this for over a decade and until recently didn't seem to mind. That's why I've got a millermatic 250 an

May seem like an odd approach but...............

when was the last time the gun liner was replaced or cleaned out......???... Ever..??... Never...??

A dirty liner can cause the wire drive motor to draw more amps and make more heat.... maybe enough more heat to help cause premature thermal shutoff on a machine that is already being pushed to the edge of it's duty cycle....??

A new liner is only $15-20 anyway..........so..........

[aametalmaster]

What size mig wire also? I have found that .030 runs the best in that machine even though the industry standard is .035, or so I have heard. Even my LWS I work at sells more .030 now than .035 for the smaller migs than they ever did before...Bob

[Oldgrandad]

Switched to a Prostar gun not that long ago with the centerfire nozlLiner is good wire runs smooth with no drag, drive roll assembly with tension spring were all replaced about a year and a half ago. I'm running .035 wire

[H80N]

Switched to a Prostar gun not that long ago with the centerfire nozlLiner is good wire runs smooth with no drag, drive roll assembly with tension spring were all replaced about a year and a half ago. I'm running .035 wire

Well...... it was a thought............

[ryanjones2150]

I like .030 in those smaller machines too.

[Miller Kevin]

Oldgranddad,

When the machine shuts itself down is the fan still running and does it still feed wire?

Kevin

[Oldgrandad]

No it completely shuts down. It is the thermal overload doing its job ( I think), its just doing it sooner than it should. We have a repeat job, it's a base frame for for a fiberglass tank. The frame is made with 1/8 steel sheet and has about 140 inches of weld. We can run about 120 of those inches continuous, About 8 years ago I would use the 185 for that job but after 3 of those welds it would shut down so I bought a millermatic 250 it does that job all day with no complaints. The 185 has been used on other jobs since then and works great, but lately it has been shutting itself off to quickly. A Miller rep came to my shop not to long ago, he thought it might be a thermal resistor on the board. Can I take the board, ohm out the resistors and replace the bad one or is there more to it than that. I have the right people for that kind of repair or is that a waste of time? Ideas? Help please.

[Miller Kevin]

If the fan is stopping it's not the thermal overload causing it. You have to be losing input power somehow, my first suspect would be the power switch on the front of the unit.

Kevin

[aametalmaster]

Thats like a $22.00 part 124511...Bob