The idea is to create a stiff current source.
You set the current to provide enough heat to melt and fuse but not too much.
There are a couple of things going on in the welder.
the transformer reduces the voltage to a level that delivers enough voltage to strike an arc.
The reactor limits the current so we have heat control.
The silicon rectifier group ( and this is based on looking at it not understanding or seeing how its wired ) add finesse to the lot by adding features to make striking the arc an arc control easier
Polarity control makes it easier to deposit metal from one side to another with a push based on electron flow ( for what its worth I do not understand all the subtleties of this part ).
We have wire feed speed control to match the heat.
We have gas control so we can shield the metals involved from the oxygen that might corrode the weld before its solidified.
Mostly just posting this design,in case any body was looking on the web at welders and wanting too see what they were buying, this one is a old hard too get parts for, fairly simply too adapt parts for if needed, I just seen one go for $700 cash with the co2 tank in ohio,i think its sold by now, most guys just buy inverter welders,i chose the old school welder.cranked it up about 150 amps.laid bunch of welds, the trans former went from 60 too 63 , degrees f. Most 100 percent duty cycles for light industrial welders are based on about.an hour at there 100 percent rating.
Hi Kevin,
This machine reminds me of the way quality used to be. It is simple in design, reliable, and built the way manly men like!
Take a look at those capacitors in there. Might want to test them. Over time they tend to go bad. Should be fairly easy to cross them to something similar. Those big diodes are pretty common too.
Thanks brit.they may be and diodes common break down over time and use.i found a contactor for 18 bucks 220 volt 30 amps, not sure the turn on voltage yet.That one turns power off and on too the primary on the main transformer,when torch trigger is applied,Not much there other than the main transformer that could not be sourced.I think a high school kid could make the little circuit board that runs the wire feed motor.Usa weld HTP 2400 crries a similar duty cycle transformer for $380.00 if i go pick up in Chicago area,good for 140 amps continous,if fan is working fast enough properly.
I have noticed over the years a lot of modern to moderately old electronics has capacitors in them that do not age well.
The Electrolytics I am talking about seem to dry out leak or break down inside in a process that seems to be caused just by age more than use
They fail with a pop and the device stops, usually this is an easy obvious fix.
SCRs and large Diodes have to shed a lot of heat.
Sometimes the heating and cooling cycles cause them to mechanically fail inside and break up.
The failure mechanism there is not age but heating and cooling cycles.
Transformers are just about the most robust parts you can have.
As long as they stay cool the insulation can last decades or more.
Most insulation is designed to last 30 years in regular service.
But the life shortens exponential if the device is operated at temperature above the insulation rating.
I found the original paper back service and owners manual in the box of parts,and it is same as the manual on line 20 amps in 230v and 185 amps out 100 percent duty cycle at 185 amps. So it says though i havent seen that good of duty cycle out of it yet,as i welded about 8 foot bead of weld the choke started heating up too about 140 f , the transformer stayed cool any way.I got too check all the ground connections too eliminate the heat source at the choke that is connected on the ground side.I may have too pull the choke off the core and de’shale and recoat.I hope the secondary on the transformer never got as hot as the choke coil.I dont think i would buy another snap on mig welder,due too the fact that they have no heat switches on the main transformer or the choke too shut power off when over heated,at least the harber freght mig welders had that much common sense,and curtisy built in too them.
It appears my choke coil has over heated,other than a loose or dirty ground,i am woundering if the contactor would cause heat at the choke if it was getting a chatter or intermitten contach due too a week contact coil engaugement,or dirty contacts, and the fan motor is running hot so time for faster fan ,like one off a geo tracker,and add a 12 volt transformer from the back of the braker switch, and let the other transformer power the wire feed instead of running the fan all so.Got half off on a short barrow 20 gauge rattle snake gun so for 650$ not too bad of mig weld tool.
The end of the snap on welder series, If you consider buying a old snap on dont but it with good faith,make sure they pull the side cover off too inspect the choke coils overheat condition, then make an offer and not before an inside inspection,or it could be worse than the one i bought.And i would say the duty cycle on the welder is more like 130 amps with a new cooling fan,and some air flow additions.
If you want to use some Glyptal 1201 and brush it on the reactor.
Clean with some generic Coleman white gas to get all the oil off first.
I use it on everything I service.
It just extends the life of the insulation and covers nicks scrapes and minor damage from over heating or abuse.
Works as long as the unit is not burnt.
Thanks for the tip wallace, I dont think its shorting anywhere yet. luckily most the heat was at the choke coil and not the transformer,when i gave it a good run.The coil got too about 125f and the transformer was still at 63f in my 50f degree shop,and i have not replaced the fan yet,I will check that stuff out.I allso will put one of are electronic temp gauges too the top of transformer and chock coil for ease of temp monitoring, and a 150 f or so pop switch on at least the choke coil too shut it down when gets too hot, till it cools,as they all should have been in the first place.
Most modern electrical equipment is wound with Type F and H materials.
In general that means that are good for between 155 and 170 c ( that 300 to 350 F)
That is the upper continuous operating temperature.
Most devices are rated to go 30 years at or bellow that in normal conditions ( clean, dry )
In practice they go a lot longer but they must be clean and dry.
Every 10 deg above the rated limits cut the life of the insulation in half.
In very short order you can kill something by running it hot.
I have worked on some electrical equipment so old its insulation is rated O ( for Organic )
This is cotton and organic/oil based varnishes.
This is weak compared to the modern stuff, but even O has lasted 75 years when well cared for.
In a pinch fiberglass resin for boats can be used to make a field repair.
Glyptal 1201 is rated as F material.
Also good for the inside of gear boxes and engines.
I paint everything with it.
If you find something old ( by that I mean 70s or older ) band it has that red coloured bridge paint on it ( usually semi gloss ) its very likely it contains 25% red lead by weight and probably some cadmium and zinc and chromium 6.
DO NOT EAT THE PAINT CHIPS lol…
Wash hands after handling such material and use common sense around it.
Use that great Scotch stretchy rubber stuff for more things everyday. Used some today to fix a TV camera light cord. Loctite has a silicone version that you can fix a plumbing leak with while wet. I used some of that to slow down a pressurized leak in a transmitter cooling system last year. Works on very light, small cables too, like lapel microphones. Also good for sealing / protecting outdoor connections.
Many gear cases use Glyptal to prevent the cast iron case from weeping oil and to seal any dirt that may have been missed ( sand from casting ect ).
Coleman uses it to coat the inside of fuel tanks on lanterns and stove.
Many engine builders use this product to seal the inside of their engines.
it helps oil run back to the sump faster.
Hi wallace,what is the continous temp rateing of glyptal 1201, can you send me a link too the stuff ,no results on ebay. Thanks for responce mike and wallace.
I know most of these products are rated F.
Westinghouse brand ( I do not like that kind because there’s comes out clumpy, has a lot more solids in it ) Says F on the can.
Dolph’s red electrical finish is extremely nice stuff with a higher gloss and light red colour not sure about the rating.
Eastman has it with all the info.
Here is a link that states it has a 135C rating.
That’s still higher than the average electrical equipment ratting for consumer grade electrical equipment ( generally insulated to class B ) http://www.glyptal.com/1201tech001.pdf
Now skip Ebay:
Do you have an electrical supplier in your town that contractors use?
95% probability they will have this on the shelf in 1201A ( spray can ).
If not they will have a generic made by Ideal or other off brand.
I dont know what fixed this welder, except i pulled the caps, cleaned the conections there and on the bolt on diodes. oiled the fan motor and she welds nice and cool 170 amps non stop.
I built this burn box in place of my fire place incert water boiler, that burner box was too small. All i have too do too this burn box is add a water jacket too the outside the burn box. The fan that feeds the fire air is seting near the cement floor too keep the smoke from exit the burn box when fan stat shuts fan off.
All the smoke go out the slot in the floor of the burn box , then travel too back of burn box and up through the water jacket heat exchanger behind the burn box.
