Old reliable Miller Trailblazer 22G just became unreliable.

I've got a question that maybe someone in here would know what to look for. I bought this old Miller 22G Trailblazer from my local town auction several years ago, for a song. It's been the most dependable and reliable machine that I have ever owned. Has really long (50 ft.) leads, and a sweet running little 4 cylinder Continental gas engine that'll fire up in any weather. I'm not claiming to be a big professional welder; I "get by" doing my own thing when I need to. It's refurbished a couple of lowboys and various other projects and worked beautifully. Yesterday I went out and fired it up to fix a thing on my Bobcat, and it wasn't making any juice. Both Volt and Amp gauges read 0. I have had to fiddle with the lever down underneath the tin hinged cover the past couple of times, which honestly I don't know what it's even for...I think it's to reverse polarity? It's like a swinging knife switch left to right, and is marked poorly with paint "". The contacts are loose on the "lever" side, I've tried to bend them in to tighten them and all, but to no avail. I even considered eliminating that switch and just jumping it direct because I'll never change it from what it was set at anyway in my lifetime. But I couldn't even get a small jump on either meter when messing with it this time. I've done a little research on some Facebook pages but no replies yet. Some of those pages I've found are nothing but a place to ridicule and harass a fella for asking a sensible question anyways, so I tend to try and stay clear from those elite welder guys that know everything about everything. I picked up on a couple of things from my researching though, like checking the breakers which I did. The next thing is the brushes...So that's when I thought I'd see if anyone here has any background in working on these old dinosaurs to see if I can get some direction... Thanks in advance. PS: Pictures are of it running at high idle, to see gauges reading zero.

have you downloaded the manual & schematic from millerwelds.com ?

I recently repaired a welder that had the same problem. I sprayed the inside every switch I could get at with Deoxit. Then worked them back and forth quite a few times. It magically started working again. There must have been a buildup of corrosion on the contacts inside one or some of the switches.

mekanik said: I recently repaired a welder that had the same problem. I sprayed the inside every switch I could get at with Deoxit. Then worked them back and forth quite a few times. It magically started working again. There must have been a buildup of corrosion on the contacts inside one or some of the switches. Click to expand... Also should blow the unit out with compressed air, check brush movement & length.

My neighbor who actually ran this machine when the town owned it saw my post yesterday on the Miller Welders facebook page. He called me last night and sent me the service manual he downloaded to his phone, and it has a breakdown of every component on this machine. So when it gets to a humanely tolerable temperature outside here in VT, I'm going to get into it and get it figured out. I'm leaning more and more towards the brushes, and there's a couple of glass fuses behind the cover that need to be checked too. Thanks for the input folks. Every little bit always helps.

DDoug said: have you downloaded the manual & schematic from millerwelds.com ? Click to expand... Actually yes...yesterday my neighbor sent it to me so I've been studying it since. I have a good idea it's most likely brushes. When it warms up to a tolerable climate here, I'll dig into it, because it sits inside of an old 24 ft truck body out of the elements, but in the cold unfortunately.

This might not be related to your ‘S-R’ switch but I have an older 10k generator (1955) with a Onan that is hand crank start. The removable crank sticks out the front of the housing like an old Model A. There is similar box on it that I have been told is used for starting if so equipped. The battery power is back feed through the gen to turn the engine for starting. So ‘S-R’ is for start-run modes? And yes I would agree it is the brushes.

Straight & Reverse polarity is my guess.

Does it charge the battery okay? I'm wondering if the exciter brushes are just tired or maybe a little stuck in the holders.

fast_st said: Does it charge the battery okay? I'm wondering if the exciter brushes are just tired or maybe a little stuck in the holders. Click to expand... I am suggesting it's time for some good PM work. Not just a bandaid for one item. Old reliable needs a bit of work to keep up being reliable. Clean all the contacts, not just chemicals sprayed all over, get out the crocus cloth. Same with the high current connections, unbolt, clean, and re-torque. Check where the brushes ride, make sure it's still round. All that carbon from the brushes has come off, and has gone somewhere, need to clean it all out.

DDoug said: Straight & Reverse polarity is my guess. Click to expand... That's what it is, I see it in the Miller service manuals.

DDoug said: I am suggesting it's time for some good PM work. Not just a bandaid for one item. Old reliable needs a bit of work to keep up being reliable. Clean all the contacts, not just chemicals sprayed all over, get out the crocus cloth. Same with the high current connections, unbolt, clean, and re-torque. Check where the brushes ride, make sure it's still round. All that carbon from the brushes has come off, and has gone somewhere, need to clean it all out. Click to expand... AGREED. It most likely hasn't ever had any TLC prior to me owning it. I love the machine enough to give it some time and refresh it. The motor runs like a Swiss clock, I did tune it up and changed the oil last summer. had a heck of a time finding points, cap and rotor for that Prestolite distributor, but my friendly neighborhood O'reilly's parts man went above and beyond and piece-mealed parts from here and there and gathered everything up over a week or so's time. It's snowing like mad here as I type, so the desire to be working outside is quite minimal. However, they say eventually it will warm up and that gives me hope, that I will return once again to the great outdoors and start getting the list of priorities generated and started on.

fast_st said: Does it charge the battery okay? I'm wondering if the exciter brushes are just tired or maybe a little stuck in the holders. Click to expand... Yes, it charges fine, the alternator works good. I fired it up this morning in hopes that it was all a bad dream of it not6 making juice, but I was just dreaming. But it was charging real good as it ran for 15 minutes.

highwayghost said: This might not be related to your ‘S-R’ switch but I have an older 10k generator (1955) with a Onan that is hand crank start. The removable crank sticks out the front of the housing like an old Model A. There is similar box on it that I have been told is used for starting if so equipped. The battery power is back feed through the gen to turn the engine for starting. So ‘S-R’ is for start-run modes? And yes I would agree it is the brushes. Click to expand... It stands for STRAIGHT and REVERSE polarity, according to the Miller service manual.

DDoug said: have you downloaded the manual & schematic from millerwelds.com ? Click to expand... I have, and have been studying it with intensity.

Probably an F163 Continental engine. Very popular in welders and extremely reliable. On Miller's you sometimes need to clean the slip rings of corrosion and glazing because they are an an AC alternator and use a rectifier to get DC current. There are also brushes that may need replacing. All the manuals are on Miller's website. Having the serial number makes it easy to find.