Millermatic 185

[Dmwelding1]

I have a millermatic 185 and can't seem to get output voltage I have replaced the Sr 1 diodes positive and negative, the contactor and relay are also new. 240 to the switch and out tested the switching board and everything is fine..... I can't find out for the life of me what is wrong. Any help appreciated

[aametalmaster]

I can't say what the problem is but i have a MM185 also. Best machine ever in my mind...Bob

[Dmwelding1]

I know that's why I'm spending money to fix it just can't get a spark. Guns good powers good just one thing wrong can't figure it out

[Aeronca41]

Please post your serial no. so we can look at the manual

[Dmwelding1]

La039440 millermatic 185 thanks driving me nuts

[Aeronca41]

Some questions to get a feel for where you are with this:

1. Is the fan running as soon as you turn on the power?
2. When you pull the trigger, does it feed wire, but just won't strike an arc, wire keeps spooling out as long as you hold trigger?
3. What is your level of training/experience working around "hot" equipment/wiring? Are you comfortable/safe checking live, lethal voltages with a meter?
4. Have you pulled the gun trigger with the cover off the machine? If so, can you see/hear the contactor (W, on the diagram) pull in?
5. Have you tried welding on various positions of the voltage selector switch? Results?

Hope we can help you get this thing fixed!

[Dmwelding1]

Thanks for the reply,
1. the fan is running full blast like it should,
2. The wire feeds and the trigger works as supposed to.
3. I have no problem checking the voltages and have the currently have the cover off. when I check the positive and negative next to the wire feed motor I get nothing even if I pull the trigger.
4. I replaced the contactor with a brand new one and it works when I hit the trigger along with the new relay which clicks .
5. I tested the leads off the voltage switch and they all have voltage and increase as the number goes up.

I replaced the sr1 with the diodes positive and negative. which the repair company said they could fix for $800..... they said that was the problem. I have 240 going in and nothing coming out. I just cant see anything else that would be wrong.. thanks again for the help.

[Aeronca41]

Looks like this is going to take some digging. Couple of clarifying questions:
item 3 confuses me a bit-the wire feed is working, per item 2, but you read no voltage at the wire feed motor?

Item 5-are you metering on the transformer tap side of the switch or at the movable contact side of the switch? Need to check the movable side. Easy access via wire 22 at the contactor. Metering is good but you need to try actually welding in several different positions of the switch to check the ability of the circuit to actually carry weld current. Need to know that before going any further.
If no go--
Do you have another gun you can try, or another welder you can hook your gun up to and see if it is actually good. If that isn't an option, Here's the sequence I would try.

1. Put the voltage selector switch to a mid-range setting

2. Connect one Meter lead to the terminal in the welder that the work lead is connected to. Meter set for DC volts. Connect the other meter lead to the end of the gun inside the welder-where the wire leaves the machine. Try welding and see if you get something near 25 volts. If so, there is likely a problem with the gun. If not, more testing needed.

3. Measure AC voltage between wires 21 & 23 where they connect to the diode bridge. Do not do this with a meter probe in each hand, for safety reasons. Use a clip lead on at least one of the connections. When working on live circuits, one hand should always be in your pocket, considering that your heart is in a direct path between your arms. You will need to have someone pull the trigger and try to weld while taking this measurement, or use two clip leads on meter and try welding yourself while watching the meter. I'd be looking for something around 25 volts give or take 5 volts or so. If you find no,or much lower, voltage, you have a bad range switch or one of the connections in that circuit. If OK, next check for DC volts between wires 24 and 25 coming off of the diode bridge. 24 should be +, 25 should be - . Read the voltage between the wires, not voltage from the wires to ground, and again you need to be trying to weld while measuring

I'm going to stop there for now-let's see what you find. Good luck! Im hoping this is going go be a simple and cheap fix once you find it, after having already replaced so much.

[Bls repair]

Is the ground cable good?

[Dmwelding1]

Wow ok great I appreciate the response very helpful. I will try all of that tonight as I'm at work. I will say that the wire feed motor is working I was testing the pos and neg underneath the drive rollers. I will try all you gave me when I get home thanks so much. I'll report back with my findings

[Aeronca41]

Any progress?

[Dmwelding1]

Not much been busy with work. I did rule out the gun as I borrowed one that works and still nothing. I measured the movable side of the contactor switch where the leads go into the switch and they have power and it increases as I go up. My problem is the two posts under the drive wheel for the ground and positive have nothing still whether I Weld or not. I tried testing the sr1 you talked about and get some reading but not sure if it's enough to power it. I'll do some more testing in the next few days because I work till sat. Thanks again for the advice

[Aeronca41]

Yeah, work does seem to interfere with other stuff a lot. :-). But, as they say, ya gotta eat.

Keep us posted.