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MrIdaho
10-28-2013, 07:06 AM
I have a Century 80gl mig welder that is presently ac output. Comparing welds with ac and dc I feel I should get converted but locating them capacitors. 23000uf 50v are big capacitors and big price tags to go with them. Seen as high as $30 each
The rectifier is under $20 and I have a broken micro wave that I could get the transformer out of for winding a choke.
Then am unable to find an actual circuit diagram. Used BING but no results for actual circuit. Can't be all that complex.
Any suggestions for parts or rare finds?

TexasTuff
10-28-2013, 09:21 AM
You might get some ideas from here. I think this is the thread.;
http://forum.atomiczombie.com/showthread.php/6736-added-a-bridge-rectifier-to-my-welder?highlight=charlie_r

trikeman
10-28-2013, 11:43 AM
If you want a simple schematic and parts list of a dc welder circuit, take a look at the schematics on the Miller site. Here's on for my old Thunderbolt (p 15).

http://www.millerwelds.com/om/o316g_mil.pdf

MrIdaho
11-01-2013, 01:24 PM
Now I am contemplating of going with a full wave bridge rectifier instead of just a simple full wave rectifyer.
Seeing how the schematic that trikeman posted has a bridge rectifier (4 diodes) instead of the simple 2 diodes.
A full wave bridge rectifier is more efficient use of the transformer output. Could be why the schematic posted does not utilize capacitors?

trikeman
11-01-2013, 02:50 PM
I had to replace one of the diodes in mine, and as I recall they were about $12 each.

MrIdaho
11-01-2013, 04:35 PM
I was looking at maybe using one of the 3 phase diodes that sell on flebay but use two of them. Need to compare prices etc.

darnthedog
11-01-2013, 10:27 PM
No idea what a 3 phase diode is. However my best suggestion is, what is the highest amperage of your welder- Multiply that by three. You voltage will be 100 volts or less. Usually 18 to 36 volts is typical welder I have looked at. So three times your Amperage and 100 volts should set you up just fine. You can go higher amperage rating but I would not recommend going lower as they take a pretty good hit when you short out the stick.
I work with power supplies and high voltage. Thus this has been my experience professionally dealing with 400 degree C furnaces. And 10KV and 40KV power supplies used to create plasma to transfer metal to a silicon surface. Anyway good luck in your conversion.

TexasTuff
11-02-2013, 01:06 AM
Hi MrIdaho
Maybe you are speaking of a 3 phase full wave bridge rectifier. They are commonly used on alternators like wind turbine alternators. Most alternators are 3 phase. The 3 phase rectifier will work but you will use only 2 of the poles leaving one open but a single phase full wave bridge rectifier is all that is needed. I did notice that 3 phase 150A 1600V bridge rectifiers are easy to find on ebay. Single phase at those specs more difficult to find.

MrIdaho
11-02-2013, 09:33 AM
I wqas referring to the 3 phase diode set ups on fleabay for $18 then just use two. Before I do anything I plan to research just how much amperage I really have. The 150 amps is what most every conversion I was looking at is using (BOY REAL GOOD ENGLISH THERE lol)
Its a Century 80GL mig welder. Same unit HD sells.
Only reason, well two reasons, why the full wave bridge set up is it utilizes the transformer output better more efficiently than just a two diode full wave setup and from what I am seeing, the better DC welders are using a full wave bridge setup.

MrIdaho
11-02-2013, 09:44 AM
going by Lincoln Electric Century 80GL Wire Feed Welder-K2501-1 at The Home Depot (http://www.homedepot.com/p/Lincoln-Electric-Century-80GL-Wire-Feed-Welder-K2501-1/100596737#specifications) y these specs the 150amp diodes are way out in left field.
Saw a set of 4 diodes for under $30 on fleabay rated at 100 amps. need to recheck that price and the set of 4 specs but it is something like that

MrIdaho
11-02-2013, 09:50 AM
here are the diodes I am referring to. Should work??


http://www.ebay.com/itm/4-wind-turbine-generator-solar-pv-600-volt-75-amp-blocking-diodes-Cheapest-eBay-/321232828301?pt=LH_DefaultDomain_0&hash=item4acaf7f78d

darnthedog
11-02-2013, 09:56 AM
Very underated per my 3x or more on amperage. Only rated to 75amp for 80 usage.
You may want to consider these
http://www.ebay.com/itm/IR-Diode-300U30-300-Amp-400V-Stud-Mount-Straight-/221306118530?pt=LH_DefaultDomain_0&hash=item3386df6182
Voltage is a little high but this should last you when your wire sticks instead of arcing.

MrIdaho
11-02-2013, 12:37 PM
YIKES!! $21, way outta my budget for this conversion.
Forgot it is 3x the amps not the voltage. Voltage is 21volts and 3x the amps is 105 as max amps is 35 according to the specs.
Off to search fleabay for lower amperage but that 150 looks better the time.

MrIdaho
11-02-2013, 04:05 PM
well if I could find a data sheet for this diodes (http://www.electronicsurplus.com/Item/8109/WESTINGHOUSE%20-%2075-150AMP%20STUD%20RECT%20-%201479%200182/)at $7.50 each
It says 75-100 amps

darnthedog
11-02-2013, 06:56 PM
The max amperage output on that welder is 88 AMPS And $21 each is Cheaper then the $33 from the link you provide before.
If you don't go 3X the Amps which is 264 amps minimum you'll probably be replacing diodes all the time. But you have been informed.

MrIdaho
11-03-2013, 07:16 AM
Your right about replacing diodes. Going to order the 150 amp units 3 phase and use two per unit for the full wave bridge

Tradetek
11-03-2013, 06:41 PM
So, I'm not going to pretend to know much (if anything) about the intricacies of this kind of conversion, but it would seem logical to ask... do you have the required power outlets to support the increase in amps that you hope to achieve? I'm pretty certain that in order to get more than about 1.5 times what you are currently running, you are going to be wanting a 220v circuit...

Bill

trikeman
11-03-2013, 09:10 PM
Now I am contemplating of going with a full wave bridge rectifier instead of just a simple full wave rectifyer.
Seeing how the schematic that trikeman posted has a bridge rectifier (4 diodes) instead of the simple 2 diodes.
A full wave bridge rectifier is more efficient use of the transformer output. Could be why the schematic posted does not utilize capacitors?

Could be. I know before I replaced the burned out diode it just always seemed to lack power on DC. I finally hooked my scope up to the output and sure enough, only half the wave was there. It welds so much better with both sides of the wave (all converted to one polarity by the full wave rectifier). If it had a capacitor, it would have smoothed out the half wave missing somewhat, but its still better to have the whole thing for more power. The Thunderbolt does have a very big inductor choke coil about the size of a cantaloupe to smooth things out (labled Z in the diagram).

darnthedog
11-03-2013, 10:24 PM
So, I'm not going to pretend to know much (if anything) about the intricacies of this kind of conversion, but it would seem logical to ask... do you have the required power outlets to support the increase in amps that you hope to achieve? I'm pretty certain that in order to get more than about 1.5 times what you are currently running, you are going to be wanting a 220v circuit...

Bill
Bill
He is not increasing power- He is converting AC flux-core mig to DC flux-core mig with the same amperage. This will smooth out the welds a bit as reported by Charlie_R. The recommendation for 3X Amperage on the diode is to keep the diode from blowing out when there is a dead short. Mig wire sometimes sticks to the metal and stops the arc. Essential shorting out. This is a huge surge on a Welder and if the diode are not big enough they will burn out like fuses. Thus the 3x recommendation. Hope that clarifies things for you.

MrIdaho
11-11-2013, 12:42 AM
After doing more research into the conversion of an AC welder to a DC welder, I ran across a couple of schematics.
One of the web sites stated that you take a 1.75 dia cast iron pipe and wrap it with #8 or #10 wire for an inductor - interesting as in theory it should work.
http://i36.tinypic.com/68y5pu.gif

http://shdesigns.org/Welding/Misc/AC2DC.jpg

MrIdaho
11-14-2013, 09:28 AM
Well parts are ordered for the conversion
two rectifier blocks and one 100mf motor run cap
http://rover.ebay.com/rover/0/e11400.m1842.l3160/7?euid=4569db29ce4b4b818db5c335e56fbc2b&loc=http%3A%2F%2Fcgi.ebay.com%2Fws%2FeBayISAPI.dll %3FViewItem%26item%3D251157591466%26ssPageName%3DA DME%3AL%3AOC%3AUS%3A3160

Now need to look over at Mouser for the additional caps and the MOV.
Still looking for the inductor choke, either an old transformer or ??

trikeman
11-14-2013, 10:04 AM
You could wind your own choke with some copper wire. I am sure the electronic websites have instructions on how to do it to get whatever inductance you want. My electronics knowledge is very rusty, but maybe Brad could point you in the right direction. It looks like this guy wound his own

http://mindtomachine.blogspot.com/2007/08/i-wound-choke-for-arc-welder.html

TexasTuff
11-14-2013, 11:44 AM
Still looking for the inductor choke, either an old transformer or ??

Dead microwave ovens are a good source for transformer cores. Check with Goodwill, they often throw out microwaves that are not working. They gave me one a few weeks ago. I stopped by last week and the lady offered me another one. Just cut the old winding off and rewind with insulated house wiring.

George

MrIdaho
11-20-2013, 03:39 PM
Still looking for a iron core for my inductor but in the process a Miller S-32p followed me home for FREE yet. Located a parts list but no inductor BUT it does have two capacitors and a rectifier. Both of which I have already ordered BUT the one schematic I posted suggested that if I use a 450uf cap I don't need the inductor. The caps in this Miller S32p are both 1200uf. The diodes are 40A 800v. Have diodes on order 150A 1600v.
never seen this so called suitcase welder??
As soon as I get the diodes I am going to make the conversion w/o the inductor. Just need to order the MOV and .1uf caps from Mouser. If anyone has one of these S-32p units and needs parts just let me know.

TexasTuff
11-20-2013, 06:03 PM
I don't know anything about the Miller welder you got, but it must be pretty good from the prices on the internet.

MrIdaho
11-20-2013, 07:36 PM
I don't think it's an actual welder but a mig conversion that you connect to your stick welder?

TexasTuff
11-20-2013, 07:54 PM
I don't think it's an actual welder but a mig conversion that you connect to your stick welder?

I saw that there were several configurations but I didn't take the time to study them. I noticed that people had the wire feeder (which is what you have) to several different types and brands of stick welders. The suitcase welders I saw were $800 and more.

MrIdaho
11-21-2013, 12:13 AM
$800!! wow I need to look at this so called welder closer. It's been sitting out in this guys field for ??
It looks pretty clean on the outside. Labels are still intact. Don't know much else. Perhaps use it for salvage seeing how it has the gun, gas hook ups etc. Will investigate further tomorrow. As I stated, if anyone wants some parts, just pay for shipping.

MrIdaho
12-04-2013, 09:31 AM
Took the Miller apart and not much salvage for what I need unless someone needs a motor and/or wire feed mechanisim. Just pay shipping. Has the gun etc still attached.
Well I got my Lincoln welder opened up and I see ALL COPPER wire unlike some of the cheaper AC mig welders as I understand use aluminum wire etc.
Well I got to figuring out how to connect the diodes (I was under the impression I needed two 3 phase diode units) After contemplating what my next move is I realize I have all the components that have eyelet ring connectors so no soldering or crimping required except for attaching the various capacitors. Hopefully get this beast back up and running by days end.

trikeman
12-04-2013, 10:23 AM
Yeah my old Miller is all copper windings and bolted connections - no soldering to replace stuff. I think even some of the newer Millers also have aluminum windings, but they still work lol.

MrIdaho
03-11-2014, 10:38 PM
Well the weather is getting really nice so I FINALLY finished the AC to DC conversion. Only one big oil filled cap and the full bridge rectifier. Tried it out by running a couple of beads. Seems to eat the wire (gassless mig 110v) up faster but definitely better penetration. One problem, I was able to crack a bead in half by bending the 90 degree piece over.. I figure I need some practice with new setup.
LOT LESS splatter and cleaner weld.
The rectifier I bolted to the welder cover as the full bridge diodes get warm.

Tradetek
03-12-2014, 09:50 AM
...definitely better penetration.


One problem, I was able to crack a bead in half by bending the 90 degree piece over..

If what you typed is what you meant and you were really able to crack the weld by bending a 90 degree joint in half, then you didn't have any penetration at all...

Bill

MrIdaho
03-12-2014, 10:10 AM
I was welding on the ground and a 16 g box tube to a 3/16 angle iron.
Going to try welding to same gage metals together today. Been out of practice and needs a different wire feed speed. I was after the results of spatter etc and I need to clean or replace the clear shield on helmet. Couldn't see very well. LOTS of little issues.