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Successful CP-200 Conversions

smilingjohn

Plastic
Joined
Apr 4, 2012
Location
newton
Hey new to the forum been lurking a while thought. i recently converted my miller cp- 200 to work on single phase. it seems to work well and i am pretty happy with the performance. im running some pretty big wire in it .045. i am able to weld 3/16 steel well with it for repairs to bobcat attachments. ill post some pics and updates later.
 
Congratulations, was it easy to reconnect? I use a very small wire on my millermatic 35 to ensure proper penetration under many different conditions.
Rob
 
It really wasnt too difficult it took me most of an evening to do. at first i was a bit skeptical as to what the outcome would be but the welder works great. dave kamp sent me the revised step by step and it cleared up my questions.
 
Hi John!

Many thanks for posting your results!

For anyone that's interested, the revised document explains not only how, but WHY the Haas-Kamp conversion works, and includes a detailed, photographed step-by-step process by which one can perform the conversion without having to dig through the dialogue of learning in my first thread, and once converted, it's not difficult to return it to 3-phase operation if you so desire.

The document is unfortunately too large to post here on PM (it's about 1.2mb), but Greg Menke has graciously posted a copy on his magic PounceaTron server:

http://pounceatron.dreamhosters.com/docs/misc/CP-200_Single-Phase_Step-By-Step.pdf

You may download, view, and print it for your own use... Please remember that these machines were made over a LONG timespan (I've been told that there's even still a version being made) so PLEASE verify prior to beginning, that what you have matches the unit I did. If it does NOT match, there's a very high likelyhood that it CAN be converted, but you'll have to do a little learning and research, so you get the correct wiring.

And finally- for anyone who's duplicated the conversion- please post your comments- both on the process, and resultant performance, so that the rest of the world can benefit from YOUR experience, regardless of what the experience may be.
 
A photo...

IMG_20120422_142206.jpgBy the way... here's a snapshot I took yesterday amidst working on some project. 3/16" thick 1-1/4" angle, with old paint on, against a piece of 1/4" thick unpainted steel.
 
Hey there Gents-

Just wondering....how do these conversions perform on aluminum? That is, assuming that said Haas-Kamp conversion is set up for MIG...has anyone tried?
 
Hey there Gents-

Just wondering....how do these conversions perform on aluminum? That is, assuming that said Haas-Kamp conversion is set up for MIG...has anyone tried?

The CP-200 is a Constant Voltage welding supply, intended for any processes requiring up to 200A continuous duty, and has slump appropriate for GMAW and FCAW processes... all wire-feed applications.

Welding aluminum requires high power, hence, it is best to utilize a supply that has a very high duty-cycle rating. The CP-200 is rated for 200A at 100% duty cycle, so it's capacity is much greater than say... a '250' labeled welder which may be capable of 250A, but has a rating of 160A at 80%, or a 150A @ 100% duty cycle.

Once the power requirements and duty cycle are met, WIRE FEED aluminum welding depends upon the wire feeding system, not the power supply. Aluminum wire doesn't feed nearly as easily as steel- it requires close attention to drag, and in most cases, you'll need a push-pull gun system, where a feeder at the welder end pushes the wire, and a second feed motor system in the nozzle PULLS it through. The other option, is feeding it from a spool-gun. The CP-200 and CP-300's were commonly fitted with both. The CP-250TS (see other conversion thread on this forum) was DESIGNED for spoolgun operation in SPRAY MODE (not short-arc modes). Using either of these supplies for welding aluminum is clearly possible, but you'll need the aluminum feeding system to do it.

Power wise, I don't see any reason why they won't work... they'll run full-rated-current through a crowbar.
 
By virtue of a forum member who's acquired a surplus CP-200 in hopes of a conversion, It has recently come to my attention that there's ANOTHER flavor of the CP-200 out there...

The original conversion was on a machine that was designed from-factory to operate on either 230 or 460v. This unit used three coils (A, B, and C) wired in Wye... and each coil has TWO sets of windings... series for 460, parallel for 230... and in both cases, the topology of the 3-phase circuit is Y. When doing the H-K conversion, we separate out each coil, drive the two end coils from the AC line, and drive the remaining (center) coil via two phase-shift capacitors. Because of the Y topology, this means that the two windings of each coil are subjected to 138v each, and when wired in series, equates to 277v, which is correct for a 480Y system. When re-arranging this wiring, we use the 480v jumper position to keep them in parallel (277) and drive it with 240v, so the coils are not at any risk of being applied an excess voltage.

Craig found a CP-200, and noted upon opening it, that the jumper configurations were different from those shown in my step-by-step. He contacted Miller's support staff, and acquired a copy of the manual, and to our surprise, the unit is listed as a 208-230 ONLY unit.

The topology is essentially same as the 230-460 unit, with exception that the transformer primary coils are not two-section series/parallel, but rather one single 230v winding, which has an extra tap for 208v.

This presents somewhat of a challenge, because that identifies the coils as being 138v, and with no ability to re-configure the taps for series (460) operation, the process documented in the step-by-step will NOT immediately work for his unit.

I spent some time thinking about this, and spoke with Peter about it, I believe we have a solution... it will, however, require experimentation and testing. I've thought about how to make this happen- I certainly don't want Craig to bear the effort of experimentation, but I DO want to try it, and if/when it results in a successful outcome, I'll do a step-by-step on the 208-230v unit as well.

That in perspective, what I will most likely do, is trade Craig... I'll take him MY supply (the actual one shown in the Step-By-Step) and bring his 208-230 model to my workshop, to become another late-night experiment. I'm 96% certain that I can make it work, and just-as-well as the 230/460 machine.

In the meantime, for anyone desiring to do the conversion, pull off the terminal strip cover, and CHECK your machine, see if the terminal layout and quantity matches the photos I show. If not, do some research first... get the serial number, get a copy of the manual, and LOOK at the diagrams, see if they match mine. If not, drop me a message here, and I'll work with you to sort it out.
 
I recently purchased a CP-200 at auction and I am in the process of doing the Haas-Kamp conversion. It is almost complete - I'm just waiting for the capacitors/resistors to ship.

The terminal strip in my CP-200 seems to be slightly different than the one in the step-by-step instructions. Instead of three groups of four terminals, there are three groups of six terminals. According to the diagrams on the panel, it can be configured for 200, 230, or 460 volts based on the jumper settings.

The additional terminals are wired to the transformers. When I did the wiring for the conversion, I just ignored the first and last terminal in each group. I'm pretty certain that this is correct based on my understanding of the wiring. I'll be sure to post an update when/if I get it working.
 
Thanks for that note, Lank... please keep posting what you find, and if you can, post how you made your connections, and pictures if you can... for the benefit of those who wind up with the same machine as you.

And in following up on my previous note- must be the moon or something- I've been contacted by three people in the last several weeks, that all have the 208/230 version. I haven't gotten the nearest one in my shop yet, but hope to trade my current 230/480 supply for his soon. Please stay tuned!
 
Another conversion, 16 Oct 12, cp-200 (230/460 v as orig design)

I finally got around to converting my machine, which turned out to be a 1979/80 version, that is exactly like Dave's original conversion unit.

I found it EXTREMELY easy to do. Rather than cut wires though, I removed them from the terminal strip on the back side (my wires are still pliable enough to move the strip out far enough to make it rather easy).

I also removed the large wires on the contactor entirely, and used the shorter two to make my "buss bar".

Therefore, converting my unit back to original would take about half an hour. I'll put the three extra wires I removed and put them with Dave's instructions in a packet inside the covers.

I need to get a bottle before I can test it, but wanted to get my conversion posting started. From start to finish, this conversion took only a hand full of normal tools, a few feet of wire, about three hours (all of which was NON frustrating) and some terminal ends. The two capacitors were supplied courtesy Ebay, 440v oil filled, about 9 bucks each, shipped. My unit, with a s-52d wire feed, two big spools of wire (70s6 and 308), extra gun, lots of consumables (tips, shields), gas line, regulator on a rolling cart was $350 and I found it right here on this site a couple years ago. So I'm into this entire thing less than $400.

Excited to try it in the next week and will post the results.

Tools
 
It's been a little while since my last post. Converting the welder to single phase turned out to be the easy part. Installing a subpanel and wiring a 240v outlet into the garage was a project by itself - far more difficult and more expensive than the Haas-Kamp conversion. I didn't actually do the math, but I'm pretty sure I spent more money on wiring up the garage than what I paid for the welder at auction.

Anyway, I plugged it in and flipped the switch to 'On' the other day and after a few seconds the welder blew up and the entire garage burned down.

Just kidding! I was actually fearing that the world would implode when I fired it up, but no... the welder seemed to work just fine. The conversion was a complete success as far as I can tell. I say "as far as I can tell" because I've never held a MIG gun before in my life and my knowledge of welding is limited to what I've read on the internet and in the one book I own on the topic. Anyway, after tweaking the settings I was able to lay a bead or two on a piece of scrap I had laying around. I don't think my welds are picture-worthy quite yet, but I'll try to get a few shots of the conversion up here soon.
 
Here are some pictures of the welder I performed the conversion on. I don't know the year of manufacture.
100_3573.jpg
100_3576.jpg

In this machine, there are 18 terminals on the terminal strip instead of 12. If you look at the jumper configurations (the white sticker) you will see that this CP-200 can be configured to support a 200 volt input in addition to 230v and 460v. That's what these 6 extra terminals are used for: accessing the additional taps on the transformer to configure the welder for 200v input.
100_3591.jpg

The Haas-Kamp conversion can easily be performed by simply ignoring these six extra terminals. I think it is best to just follow the instructions in the step-by-step document as though these six terminals were not there. You'll see that when I numbered the terminals, I didn't assign numbers to these six extra terminals to avoid confusing myself.
100_3592_second.jpg

From the outside, my welder looks a lot different than the one pictured in the step-by-step conversion document. However, the guts of the two machines are pretty much identical. Other than ignoring the six extra terminals, no other changes to the procedure should be required for converting this machine. Very easy.
 

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Nice work, Lank!

Yeah, your CP is newer... probably late '70's to early '80's vintage, and they did have a few variations. Good catch on the 200V terminals, and you dealt with it well. The important note that I'm stressing here, is that there's enough variation over time, that when doing these conversions, it's important to look out for these little differences. Another note to add, is that since yours had taps for 200v, it may-very-well-be possible to utilize the lower-voltage tap-points to move the centerpoint voltage from 277v down towards 240v, and if that's the case, the delta-to-wye alteration on the OUTPUT side would be unnecessary. For those that are willing to delve just a little deeper, draw it out, and see what the possibilities are! For those that aren't, go burn some metal, and try not to smile, so your teeth don't get all weld-dusty!
 
Dave,

First, I'd just like so say thanks for the work you've done inventing this conversion and documenting it. Thanks to you and your helpful instructions, I now own probably the only constant-voltage welding power supply I will ever need. And it cost me far less than the cheapest welder available at Home Depot or Lowe's.

As far as utilizing the 200v taps goes... I think that's a great idea. I spent some time thinking about it and staring at the circuit diagram and I thought I understood what was going on but now I have some questions:

The CP-200 conversion document indicates that with 3-phase power connected to the welder, each leg of the Y is a 277v winding when in series. With 480v 3-phase power hooked up, the phase-to-phase voltage would be sqrt(3) * 480 or about 832v, correct? That should mean the voltage across each leg would be 416v with the coils in series. With 240v 3-phase and the coils in parallel, the voltage across each leg would be 208v. There must be something I'm misunderstanding here. If we were driving 240v through a coil that was designed for 416v, I don't think the welder would work so well.

If I can understand what's going on.. I might actually like to try utilizing the 200v taps. I'm very interested in pursuing this but I think I need to understand it better.

-----------------------------------------------------------------

Update: I think I get it now. In what is commonly called a 480v 3-phase system, 480v is the phase-to-phase voltage which means the phase-to-ground voltage would be 480v / sqrt(3) or 277v. Sorry... new to this whole 3-phase AC thing.

This means in a 200v 3-phase system, the phase-to-ground voltage is about 115.5v. The CP-200 would be designed to handle 115.5v across each "leg" of the Y with the coils wired in parallel. Using the 200v taps with the coils in series is not a configuration which Miller ever intended for anyone to use, but the equivalent design voltage would be 231v per leg. If we treat each of these coils as a 240v load, we're pushing it a little but it is not a huge difference and probably perfectly safe.

If we were to use only one of the 200v terminals in each group, we'd be pushing 240v through a coil intended for 254v. We'd be a bit underpowered in this case.

Either way, the secondary side should be reconfigured back to a delta.
 
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Well, sorta.

Thanks for the feedback, Lank!

This means in a 200v 3-phase system, the phase-to-ground voltage is about 115.5v. The CP-200 would be designed to handle 115.5v across each "leg" of the Y with the coils wired in parallel. Using the 200v taps with the coils in series is not a configuration which Miller ever intended for anyone to use, but the equivalent design voltage would be 231v per leg. If we treat each of these coils as a 240v load, we're pushing it a little but it is not a huge difference and probably perfectly safe.

If we were to use only one of the 200v terminals in each group, we'd be pushing 240v through a coil intended for 254v. We'd be a bit underpowered in this case.

Either way, the secondary side should be reconfigured back to a delta.

Yeah, per your discovery, a 480v Y-circuit yields 277 from any corner to the center connection point. This is what I 'broke apart' not only to provide me with three 277-voltable coils, it also gave me access to both ENDS of the 'B' coil, to slap phase-shifting capacitors in place. This however, requires that the 230/460 jumper be set to the 460v position (coils in series, not parallel)... because in parallel, each coil would be at WAY TOO LOW a voltage. Don't really wanna think about running 'em at 115v...

My thought about the 200v tap... and this TOTALLY depends on how those coils are actually wound... is that the voltage across each 'leg', if it were appropriately tapped, would put each coilset at closer to 240v. Without seeing it on the schem, I wouldn't take that guess any further, and without having one on my bench (to potentially sacrifice to the Gods of Magic Smoke), I wouldn't recommend it to someone unless they were willing to accept it's martyrdom for the cause. ;-) It is, however, something I've contemplated, and may revisit with this 208/230 variant that has recently come to my attention.

Burn metal, and enjoy!!!
 
Dave,

I couldn't help myself... I just had to try a configuration using the 200v taps. I set it up using the 200v taps with the coils in series. It was actually very simple:
--Start with the welder in the H-K conversion configuration
--Number the terminals 1-18 starting at the top
--Remove the jumpers connecting terminals 3<->4, 9<->10, and 15<->16
--Run a wire from terminal 1 to terminal 6
--Run a wire from terminal 7 to terminal 12
--Run a wire from terminal 13 to terminal 18
--Reconfigure the output side to delta by removing the shorting bar from the contactor and reattaching the original wires

It looked good on paper, anyway. Didn't actually seem to work so well, though. With the welder set to about 17 volts, it was producing about 10 volts while welding. It had previously been putting out about 16-17 with the same settings, while welding on the same piece of steel. The flux-core wire was just spitting everywhere and I couldn't get a decent bead like before. I took it apart again and re-configured it back to the original setup in the Haas-Kamp conversion document and it worked fine again. So the good news is that I don't think I burned anything out. I haven't managed to figure out why I was getting such a low output yet, but I will give it some more thought.

A schematic including the 200v taps is included in case you or anyone else is interested.

CP-200 Circuit Diagram - s.jpg
 

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Alright, so it's been a few months rather than "next week" but I finally had some time to play with the welder.

Well, actually, I tried it within a day or two and it didn't work at all! HOWEVER, in usual Dave Kemp style, he's got a troubleshooting section in there. I had horrible bead stability. He recommended cleaning the brushes and sweep areas on the transformer, which I did this morning. Put it all back together and had horrible problems with wire feed... my welder came with a MILLION POUND roll of 70s6... that's a little rusty. After deciding to quit fighting that, I put on a roll of stainless that came with it.

The welder works great! I don't, but that's a matter of burning up some more wire and getting the feel of settings.

The point is, it's a beautiful conversion. Nothing in that machine is damaged or non reversible with an hour's time. However, for $250 I have a SERIOUS Mig welder that performs beautifully. The conversion is child's play and REALLY well engineered and documented.

All the naysayers are just that. They may have some credibility if they were "naydoers"... but I imagine they'd have the same results as the rest of us, and realize it works.

My only recommendation for someone doing this is to realize you're inherently playing with an old machine that is likely going to have some issues due to it's age, like corroded brush sweeps, worn feed rollers, etc. Those problems aside, the conversion works as advertised and works really well. I'm even running this off a quick and temporary 220v/20amp line I ran. A measly 20 amps and it works great on 1/8" stainless steel. I'll put in a better circuit and have one in the other shop. I just put these circuits in with dryer plugs so it's easy to move around to where I'm working. I've also fabbed up a 30' drop cord (10 gage) so I can work way out in the driveway.

THANKS to Dave for doing this, putting up with the BS and for his personal support for my conversion (I contacted him directly to help with internet link problems). Honestly, the conversion takes about 2/3 of a nice morning and isn't frustrating at all. The parts (capacitors) came from ebay for under 20 bucks I think. I took my time, walked through it mentally, then found parts and got familiar then dug into it. Take your time, verify your wiring and don't rush it, it'll work fine.

I've still got some learning to do and will try to get some pics here pretty soon, as my TIG welder is down for repairs!

Cheers,

Tools
 
Well, it's confirmed, the welder works great. Turns out, I had my polarity backwards... hence the really thick buildup and very little penetration. Also, got some good clean wire and everything works very well. Dials down really well, blasts through 1/4 like butter WAY down the scale on a 20A circuit effortlessly. This is a really nice welder.

I have some pics I need to upload of beads and penetration, and remember, these are the FIRST beads I've EVER made with a mig welder.

Tools
 








 
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