Dead sp-170t

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Hi all,I picked up a used Mig welder and was assured that it worked.I changed the plug and I get nothing. No fan or anything. I plugged my Arc welder in and it works fine.Took the cover off and did a continuity test and the plug is wired correctly. I tugged on a few wires to see if there was any corrosion on the spade connectors and still nothing.Went back in the house. Yelled, cursed, kicked the dog, drank heavily...  and all of a sudden the fan worked  so I pulled the trigger and it all went... well it stopped working.I'm taking a wild guess and saying it's the thermostat. But I have nothing to base it on.There is a schematic on the back of the manual.http://content.lincolnelectric.com/p...r/im/IM794.pdf Any help would be greatly appreciated.Thanks
Reply:You verified the on-off switch?? Then I see a N.O. relay on the other leg too.
Reply:Yes I did verify the switch. I get 122V from ether side. Never tested a relay before. Any advice on that?
Reply:Ok, both terminals on the N.O. relay are putting out 120. H2 is also putting out 120 (it was there so I checked
Reply:Got some time to do a little more testing.I was guessing that all V are ACLine 214 & 211 are pushing ~20V I remove the connector from the circuit board and tested the connector end1- 162- 203- NC4- 95-3 6- 217- 28- 109- 2110 NCFan connections (LS1 and top H2) are showing 120 V but fan is not spinning. turns freely...Anybody sees anything wrong?
Reply:That fan should run no matter what. It's a simple 230 volt fan and about as shallow into the ciruitry as you can get. Turn on the switch, the fan is right there and away it goes. It'll run whether those thermostats are open or closed. In fact it should run during all themal shut downs to help cool things off. If the fan is good and you've got 230, it should run. If it doesn't run, not much sense going any farther till it does. You've measured 120 to ground about a dozen times looks like. Sounds silly but you have measured 230 across, right?That ckt breaker isn't popped is it?Last edited by Sandy; 03-01-2009 at 11:35 PM.
Reply:Sandy,You're absolutely GENIOUS!!!. You're correct. It never dawned on me to put it across the 2 terminals. I'm getting 0 across that.So I checked the voltage across the 2 poles at the switch ^& I'm getting 0 there too.I believe that means that even though witch at the breaker is 240, it's on the same poles. Is that correct?It's odd that my arc welder works on that same circuit thoughI pushed the breaker button in just in case.Thanks again. and it's much appreciated.
Reply:I believe that means that even though witch at the breaker is 240, it's on the same poles. Is that correct?It's odd that my arc welder works on that same circuit though
Reply:My guess is that its in the machine, since you say the other welder will work.I would start with checking the voltage across both legs at the outlet. Got 240v? if so its somewhere in the machine.Since you said it works, then it doesn't, I'm thinking it's a bad connection in the plug, or a bad wire in the cord. to start with. This can be a PITA to find, because when you test it it may work, then when you go and weld you move the machine and loose the connection. That would also account for only 120v if only one wire is disconnected.No offence, since you f'd with the plug, I would start there and double check all the connections.
Reply:Check the fan motor connections as this is the supply to fan and also is auxillary transformer supplying the board. The connections there are flimsy, I have had some problems at that point.CheersBilly
Reply:Ok, Got it running. Big thanks to everybody, especially Sandy!!! The 240V outlet was reading 0 so I opened the fuse box and the 2 posts on the fuse read 240V. First though was. WHAAAATTTT????Well looking a little deeper, with continuety tests from the outlet post to the switch post. Black works. Red is intermittent. Very intermittent. Checked the wire on the outlet. good. the red wire on the breaker? disconnected. Must have been that way for years. Probably got loose when I pulled the plug.Fired up right away after that.Now I need to practice so I can weld up a catalytic converter.Thanks again to everybody.