View Full Version : Lincoln R3S-400 broken

09-24-2008, 03:09 PM
I think the rectifiers have given up the ghost, problems came on all of a sudden, it just won't weld. The machine is 1970s vintage, rectifers are stacks of smallish diodes in parallel, near as I can tell.

Is it worth trying to fix this antique, or should I shop the auctions for a replacement? The Miller feeder still works fine.

Interestingly, I picked up the rectifier assembly from an Airco welder at the scrap yard just the other day. It uses 12 big honkin' diodes instead of stacks of little ones. Unfortunately, it looks like it'd be a heckuva job to transplant them into the Lincoln.

I could buy one of those little suitcase MIG welders, but it's nice to have the high-power capability if I ever need it.

09-24-2008, 04:25 PM
Bunch of smaller stud diodes, right?

Chances are only one diode is bad. That one will short out the whole machine. Take an ohm meter and check them out one by one. You may need to take the leads off to isolate them.

The diode shouldnt be more than $30.

09-24-2008, 07:37 PM
It appears as though each rectifier consists of 8 diodes that look like they're soldered in. (I didn't remove the assembly) I do see that only a single shorted diode would kill the thing.

Kinda had high hopes for the Airco rectifier, but it would be major surgery to make that thing fit or to transplant the diodes into the Lincoln architecture.

09-24-2008, 09:01 PM
I hate those composite rectifier assemblies.

If you need a 400 amp machine its probably worth fixing. I dont think the rectifier assembly is all that expensive, maybe a couple hundred at most.

Or scrap the copper and make a nice down payment on a Miller Deltaweld or Dimension! ;)

09-24-2008, 09:33 PM
Hmmm.... I'd pay a couple of hundred for a new rectifier, if that's all it is. The welder's worth that to me.

10-31-2008, 09:15 AM
whats cheaper fix it or replace it

if fixing it is cheaper then go for it if you can replace it for the same money then replace it but keep in mind the old stuff is usually built better then new stuff but then again its a 50 50 crap shoot either way.

if it were me personaly and it was cheaper to fix it.. then id take my money and fix it ...

11-01-2008, 03:33 AM
Old stuff is not better than new stuff when it comes to welding. If one thing goes you can bet something else will be coming up as well. Especially in machines that are in the transition period between electrical controls and electronic controls. Electrolytic capacitors only have a life of 15 to 20 years on average.

So many weld shops seem to only have one welder. And if that machine is down then their whole operation is down. I dont know how many time I have seen this happen. Some times it is a whole lot cheaper to just buy a new machine than it is to wait to have a machine fixed. Sure it will only take $200 to 300 to fix, but the average turn around time for a weld shop is 2 weeks. Thats a lot of lost production or lost jobs during that time.

11-16-2008, 12:02 AM
well in the case of a welder then. I would think it would then be a good idea to have a back up one in the closet just in case. and as for the older stuff it was built right just like older cars better built less hassels as well..

i never went for a used lathe or mill cause a tool like that would cost me to much to get it put up top spec. where as a new one is ready to rock and roll and so far my purchaes on new equipment have been good to me.. i have very little in used stuff at all .. but the stuff i do have is still better quaility then some of the new stuff out there ..my arc welder i got used and its a great little machine for a 70 amp , sure you will say its to small and go bigger but there is no need for that right now.

but when i do il be shopping for and older one , first thing is to strip it down redue all the solder joints and stuff and then give it a go and if it breaks who cares i can have it running in a day. and you know a shop that has one go down can rent one while their main machine is getting fixed so down time is a bit of a cop out , i use to work as a mechanic and if we had a tool go down we just reneted what we needed till ours was fixed or replaced this way we lost at most 1 hour of time ..

but its always good to have a back up tool in hidding

11-16-2008, 02:00 AM
I wish companies that relied on their welder would have a spare. I dont know how many times I have heard "I need is ASAP as production is down without it".

Older cars were built just as they are today. Just good enough to pass the standards required of them. If there were not for the enviromental and safety guideline the cars would be a whole lot simpler than they are. Also people expect more features in a car then they used to be. Modern cars are many, many times more reliable than old cars. Some dont even require plug changes till after 100k. I have a little dodge neon and that thing is 1000 times more reliable than my old 57 chevy. it has never not started. Never died on me. The only time it left me stranded was because of oxide in between the battery terminals. Scraped it off and away I went.

But on a welder like the R3S-400, you are talking about a big 400 amp machine. 4 or 500 pounds at least, about 10 sq ft of floor space, and runs off of three phase. Not many closets to hold something like that.

Kinda like keeping a spare bridgeport if you other went down!

Wouldnt bother stripping down a machine and redoing the solder joints. I have never once had a failure due to a bad solder joint. If you do get a used machine open it up, blow it out with some air and close it up. If the fan has oil hole put some oil in it. You will actually do more harm than good if you went though and resoldered the connections as the boards are sealed with heavy lacquer or silicone.

Welders are some of the most rugged built electronics available. You dont need to baby them. When the dust gets a couple inched thick inside just dust them out. or pressure wash them and let them dry for a couple days.

11-16-2008, 11:06 AM
you could i suppose have a 225 amp spare welder in the closet , didnt realize the 400 one was so big , so ya a git big for a closet gota agree there.

i would agree my new pontiac G5 is a very realiable car but its not a car you can just dive into and work on ,, the older stuff is easy to work on and can seem to take a better pounding as well.

todays engines are so easy to blow up form hard driving where the older cars that still had cast iron blocks you could terrorize the hell out of them with out much complaint from them,.. someting about older stuff just makes me feel safer, but then again the older the car the more often you work on them to so its a give and take deal i guess ...

i found the old Black and decker jig saw a week ago that i used to run the hell out of has not even seen oil in years now and anyhow luged it in and still runs like new,, the other day i was out looking ofr a palm sander and founda B&D on sale at walmart for 20 bucks so i bought it and its a great little toy best thing i bought the wife in along time so now she can get the kitchen cupboards all done now ,,

back to welders ,any how my littlle lincon is a few years old and i got it used only thing i needed to do to it was repalce the elctrode holder it was well used and well abused.

i havent taken it apart yet but thats going to be this winter just to make sure its all cleaned up and what not.. i also gota find a better place for it and mod the shed again so i can fit an aircompressor in there,,i really need a new larger shop , perhaps next year..

but ya if all you got is one welder then thats a big problem when it comes to making money so id have to say if need be go get a 225 or something or rent something and get the big bad boy fixed so it will turn another 20 years..
true the life spane is not the best on electrolitic caps but regular caps are just as bad in some cases as well.. i imagan that big welder is worth a few K's so id still say get it fixed , and still get a back up welder even if its half the power and still can do the job and can fit in the closet for storage..


11-16-2008, 11:35 AM
I don't use my welders to make money, they're strictly for my own use. The reason I wanted to replace my big 'ol Lincoln CV power unit with a similar one was simple: a used 400-amp unit would be cheaper than a new "suitcase" job. As most of you know, industrial 3-phase equipment is often sold much cheaper than new homeowner-style stuff, and I have the 3-phase power to feed it. As it turned out, it cost me $250.00 for the big Lincoln, and required miinimal work to adapt my existing cart and feeder to it.

If I had a real NEED for such equipment, I'd have a spare or I'd pay the big bucks to get a replacement for a broken-down machine in order to get back into operation quickly. You'll get no argument from me that it's a bad idea to keep customers waiting because an old machine is broken.

11-16-2008, 11:29 PM
so sorry did not relaize you were not using it to make money with , either way id fix it i hate throwing stuff out,