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Tommy2174 07-02-2019 12:26 PM

Help on Miller Bobcat 225 10,000w
Hey guys I'm new on here and I have a question about my Miller Bobcat 225. Where my leads plug into I'm only getting 2.4 volts. It does not want to arc. If I put the settings to Wire + and 19-28 volts at max. I can weld a little.
I have checked fuses, I cleaned the brushes, I've unhooked and cleaned all my contact points, I checked the capacitor with a tester and its good. My rheostat gets from about 20 to 30 volts. I have checked and cleaned my R2 resistor. My rpms are about 3,600. I took apart my SR1 rectifier and cleaned it. I get power to my 120v and 240v plugs. They work fine. I have know idea what to check now. If someone could provide me with more info I would really appreciate it. I do have a print out manual of this welder.

milomilo 07-02-2019 12:53 PM

Welcome. You will need to post a wiring diagram so the folks here can give you some advice to determine the problem.

Shade Tree Welder 07-02-2019 12:55 PM

What is your serial number there often many versions of a particular model.

I am no particularly familiar with the Bobcats.

This is odd in that you are getting AC power and not weld power. As the
Bobcats use the same windings for both on the Alternator, now with that
said the Bobcats generate AC power then rectify it. You might have a
something wrong with the rectifier.

I would start with the output from the windings and then trace the system
step by step and see where you start getting wonky readings.

Sounds like a loose/broken or corroded connection.

Tommy2174 07-02-2019 01:42 PM

PDF of my Miller Bobcat 225
1 Attachment(s)
Bobcat 225 PDF

Tommy2174 07-02-2019 01:51 PM


Originally Posted by Tommy2174 (Post 738126)
Bobcat 225 PDF

That PDF should have everything on my welder. I have the kohler engine.

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GWIZ 07-02-2019 04:24 PM

Is the machine weathered?

Check the 120 volts with a 100 watt light bulb Incandescent (basically load testing or with a power drill).
voltage does not mean a lot if there is no power behind it.

with machine not running,
set the welder knob to AC and with your meter on the lowest ohm setting measure the resistance across the two welding terminals, figuring it should be fairly low, likely less than 1/2 ohm.

While you are at it set the meter on the higher ohm scale and check for any resistance to the metal case of the welder from the terminals.
test for ground shorts.

how does it weld on AC?

Tommy2174 07-02-2019 04:58 PM

It’s been used with a 30amp welder

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Tommy2174 07-02-2019 05:38 PM

Miller bobcat 225
Yes it has some weather, it has 1654 hours on it. I just did a big tune up on it. all new fuel lines, filters, spark plugs, fuel filter, air filter, oil, and a couple other things. I just got it not to long ago. the last guy used it just as a generator for his mig welders. he was not good at stick welding so he never tested it.

Tommy2174 07-03-2019 05:56 PM

Should my rheostat read around 100volts?

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moe1942 07-04-2019 10:11 AM

Turn the rheostat up to 100%..

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