Need help, Trailblazer problems

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Several times through the years My TB won't produce an arc. It is always with the second rod, first runs good, second one no arc. Usually I can turn the machine off and wait a few minutes and every thing is fine. It only happens about once or twice a year. It did it this morning but this time I can't get it to produce an arc and I've been trying for 3 hours now. Any body have any suggestions?
Reply:Wire brush all the lead connections for starters, then take apart your work clamp connections, make sure you are using a cast work clamp, not the sheet metal POS, and make sure make sure that and all your other cable connections are clean bright and tight. If that doesn't fix it, it may be the machine contactor, which is beyond my pay grade.
Reply:I took a welding rod and bent it so I could touch the two lugs on the machine and didn't have an arc even there. It's definitely above my pay grade as well.
Reply:You may have to mod your control board Bob. My 87 TB 250 (just like yours) had troubles when I first got it. It would work for awhile, then no output. Shut it off and start it back up, all good. Then it would do it again. I sent it out to get fixed, tech said nothing was wrong. A day later, it did it again. I ended up getting in touch with John in Performance Engine Drive at Miller and he gave me the info for the mod, which is basically a jumper between two connections on the main board IIRC. He explained to me that it was supposed to be a safety feature that would shut the weld current off if the OCV fluctuated and got too high.Turns out any hiccups with the machines RPMs can also trip the feature as well. The jumper bypasses this and allows the machine to run without interruption. The Exciter Field Shutdown board (PC 3) is most likely causing the problem.Unfortunately, when I sold my machine, I had written the mod down in my manual and it went with it. I can't remember off hand what board the jumper went on. I want to say it was the main one, and it had wires mounted directly on it and coming out of it that I cut and butt spliced together. It's been a good ten years since then so I'm not 100% on the details now.  If you call Miller and ask specifically about it, they should know. I dunno if they even call it performance engine drive anymore, but I'm sure someone should know about the mod.If you need a tech manual for your machine, hit me with an email address and I'll send you one.Last edited by 7A749; 08-10-2015 at 11:24 PM.Expert Garage Hack....https://www.facebook.com/steven.webber.948
Reply:7A749, thank you so very much. I've been putting up with this ever since I got it. No arc, turn off machine, wait a while, start and get arc. It only happens about twice a year so not too big of a head ache but still not right. I'll call tomorrow. Thanks again, Bob Pool
Reply:My oldest 302 does that if you start it and strike an arc without warming it, then it chokes and dies and restart it without turning the ignition switch off first. Is that an issue too>
Reply:Originally Posted by Bob7A749, thank you so very much. I've been putting up with this ever since I got it. No arc, turn off machine, wait a while, start and get arc. It only happens about twice a year so not too big of a head ache but still not right. I'll call tomorrow. Thanks again, Bob Pool
Reply:Originally Posted by 12V71My oldest 302 does that if you start it and strike an arc without warming it, then it chokes and dies and restart it without turning the ignition switch off first. Is that an issue too>
Reply:So how about low RPM levels? I know they get slower as the governor linkage wears in. One of my newer ones with the Subaru lost 200 hi idle RPMs in 250 hrs. Just curious.
Reply:Originally Posted by 12V71So how about low RPM levels? I know they get slower as the governor linkage wears in. One of my newer ones with the Subaru lost 200 hi idle RPMs in 250 hrs. Just curious.
Reply:Originally Posted by 7A749Holy cow. I don't recall mine losing anything. If it did, it wasn't anything near that. I have the Kohler engine in my machine.The deal with that shutoff board was to protect the operator from open circuit voltage levels going too high. Since a DC generator or AC alternator's output level is primarily controlled by the RPM the motor or engine turns, if it were to increase to a very high level, the voltage on the weld output terminals would also increase. Most static welding machines in general are going to be 60-80 on average. Get that number up over 100 and the potential for electric shock becomes very real and potentially hazardous. A gas engine running at a higher than average RPM would also increase OCV levels. With very early Lincoln Engine drives like the SA 200 junior, the RPM was the primary way you adjusted the weld current output. The throttle would lock at certain positions and at that engine speed, the generator would put out a specific amount of current.Now, the old Lincoln motor generators had adjustable OCV for easier starts and changing the characteristics of the welding arc. These days, manufacturers are highly conscious of liability, so keeping it as low as possible is the name of the game. I'm sure there are other variables, but I'm only speaking from a layman's point of view.
Reply:I don't see a number for tech support on their site, would you happen to have a number to call?
Reply:I got it welding again. Emailed Miller and a tech helped me out. You were right 7A749, it was the OCV shut out board. They told me to cut wire 55 and that would get me back to welding. That is not supposed to be a permanent fix but OK until I can get it fixed. They seemed to think it was an engine problem but mine seems to be running smooth as silk. Other than oiling the linkage, they didn't give much of a permanent solution. Thanks again so much for your help, Bob
Reply:Cool!  I remember having to jumper wires together but maybe there was more than one way to do it.I think I may call them and ask if there's another remedy for the problem. It's been a good ten years tho, so maybe that was the fix then. There seemed to be more to it when I did it.Whatever the case, glad it worked out for you Bob!Expert Garage Hack....https://www.facebook.com/steven.webber.948
Reply:Originally Posted by 12V71I was justwondering if low OCV would create board problems too. On the Subaru low speed issue, I assume that was burrs on the linkage that wore off quickly. Its stayed at the same RPM since that initial adjustment.
Reply:Originally Posted by BobI don't see a number for tech support on their site, would you happen to have a number to call?