View Full Version : Midstates 300 Inert

03-21-2012, 09:38 PM
Does any one have one?

Jim Caudill
03-22-2012, 04:27 PM
Your message is less than clear. Frankly, I had never heard of a "Midstates 300 inert".

After some searching, I did find a free Technical Manual that may be of some assistance. In my searching, I noticed that you purchased a somewhat non-functioning Midstates 300 amp welder that is capable of TIG welding (when working properly) last November for around $200.

I don't know how many 300 amp welders that Midstates made that are "TIG ready", but this link to a downloadable pdf version of the manual may help you get yours working. If not, then others may benefit from understanding what it is that you are seeking.

Here's the link:

03-22-2012, 07:22 PM
I thought he was asking for a 300cf inert gas bottle from Midstate welding.

04-06-2012, 12:40 AM
The Midstates Inert 300 is a 300 amp Tig welder that came with 2 torches and everything but the flowmeter + 200+ lbs filler rod (assorted types). I have wired it up and it works. There are a set of points inside that need cleaning. I was wanting to know if anyone out there has the same welder. It is supposed to be the same as a Airco Heliweld 2, just wanting to get some feedback on any ajustments ect.

04-06-2012, 03:37 AM
If it is the same as the airco heliweld II you might be able to get some info from esab tech support. That thing was made partially by them. Other than that you are going to have to find an old welder repair shop which still has the manuals on paper or fiche.

Post a pic and I can tell you if it is the same machine.

Try around .008 for the gap. Its not that critical.

04-07-2012, 02:15 AM
I haven't got the pic thing figured out yet. So the points have a screw type ajustment? On my welder there is a door at the top face of the machine with a key lock. Behind the door is where all the relay's are and switch's ect. The points I belive are in the upper right hand side. The guy I bought the welder from didn't have the time to mess with the machine as he had bought an estate sale and didn't have room for the welder. True to his word the welder does run on the stick sidee and I'm positive it will also run on the Tig side. The points need to be cleaned and re-gaped as they don't lock in they just buzz. It also could be a power problem inside the machine but the guy at the local welding shop said it was probably the points needed cleaning. The machine had been stored for a good 20 years I was told.

04-07-2012, 02:45 AM

Are you talking about High Frequency points or something like the main contactor? If the machine buzzes you may have dirty poles in a contactor somewhere. You can disassemble it and clean out the could and it should quiet down.

HF points will make noise when they are being used. Kind of a frying bacon sound.

04-08-2012, 11:47 AM
yes the noise sounds like eggs frying and I ajusted them to .008

04-10-2012, 11:28 PM
Name is Mike, for the fella that has knowlage about this type of welder; I look further into the machine, through the door opening with the door limit bar undone, and see there are at least 2 relays down to the lower left side, is yours that way? I have an intermitant problem with the HF comming on. When it's on the points buzz and the HF light is on but it seems like a switch thing. But then I see the relays and wonder if it's a bad relay. The relays are a tall cube type. Do you have this type? Thank's Mike

04-11-2012, 04:40 AM
Relays do go bad. Pull it and look up the number to get a replacement. Nothing terribly special about them.

04-14-2012, 12:13 AM
To Macona, I have got everything working for the Tig and using the pencial torch for low ampage. I do however have an intermitant contactor. Sometimes I have to wait a minute or more for the contactor to turn on. At first start-up the contactor will work, but then falls flat. It acts like the electromagnet is getting hot and fading or the relay is going out. Looking at the front of the machine, I took the left side panel off and it exposed 2 large relays and 2 tall cube relays. On one of the big relays the points are burnt. It is the type of relay that I use on diesel engine glow plug system's. I think it is a 50 amp DC relay. The tall cube relay's control these bigger relay's. Do you know if one of these relays might control the contactor? One of the tall cube relay's has a higher resistance than the other on the magnetic coil and one relay is activated when you throw the main breaker on. The HF works everytime now after ajusting the points. I made a weldpool with the torch but I can't Tig untill I get the contactor circut repaired. Mike

04-14-2012, 03:08 AM
Doubt it is the main contactor that is causing the problem. I would start with the small Ice cube. Thats the cheapest. Read the number off it and pop it into google and someone should have it. Probably about $25.

If that does not fix it then replace the main contactor.

04-16-2012, 11:04 PM
Looks like the cube relay operates a 50amp DC type relay that I see has burnt contacts. This must be the relay that closes the contactor. I'll check the circut to see. You have been a big help to me just sorting it all out. It looks like the main contactor is down in the back near where the power cable comes into the machine. The Airco Heliwelder II looks identical to my Midstates. On mine, someone has wired in a toggle switch between the current control knob and the remote contactor and amperage control switches. It's some sort on contactor control switch. I've got it disconnected from the power source and am going to trace it (the switch), perhaps the guy that owned it had some sort of contactor relay trouble and tried to bypass the relays. Thank you!

04-17-2012, 03:05 AM
Talk to Esab, they may have schematics. If not try Arc Products in San Diego.