Airco Spoolgun married to MM200

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Hi all,Looking at picking up an old Airco Midget AH20-E gun to wire up to my older version (white face, 4 pin SM-1 plug) Millermatic 200.  The gun comes with a 115v control box, and I'm pretty sure it would be simple to wire up a plug for the contactor circuit on the MM200 from the box and install a toggle to kill the wire feeder drive motor and call it good, but I'd love to make the Airco play even nicer with the Miller and see if I could eliminate the control box altogether and wire a 4pin Amphenol plug to the thing and and use the MM's existing spoolgun control circuitry.  Any of the wizards here know if the Airco's circuitry is exactly the same as the newer PROFAX 200 version?  I've hunted for schematics to no avail...  The MM puts out 36VAC on the SG circuit, rectified to DC for the gun, and I suspect the motor on the Airco is 24V, so a step-down would be needed, and a contactor control, and what I assume is a jumper to shut off the wire feeder in the machine (gotta take a look at the diagram again, but I assume that's how that works).Unrelated- but the MM also seems to not stop wire feed right away when you let off the gun trigger- kinda rolls to a stop.  Causes a lot of stuck wire as the runout continues post weld.  I assume I should start by pulling apart the drive motor gear box, but I thought I'd ask around here to see if anyone had encountered something similar.Thanks in advance!
Reply:Call profax/lenco.  Their tech support guys are pretty knowledgeable. I used to have one of those and the Airco control box was mounted to the side of an Airco branded 330ABPTiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:O.K.  then connect to a PWM speed control board (ebay) then connect to the airco , not sure if the airco has a potentiometer or a wirewound rheostat , if a wirewound then you do not need a speed control.you  need a miller adapter to get gas and power to the spool gun. here is a simple schematic to give you an ideamm wire not stopping may be a power resistor connected to the motor used as a brake
Reply:Well the AH20-E gun operates off arc voltage whereas the early MM200 spoolgun circuitry is configured for the direct voltage operation of the Spoolmatic 1.Presuming the 115V weld control box you have for the AH20-E is the equivalent to the Profax AEC 200-1, you'll need to use that in order to get the Airco to work off your MM200.The only pins you'll need to use in the 4-pin SG receptacle on the Miller are B and D to energize CR2 within the MM200 that will activate the main weld output contactor WITHOUT running the wire feed motor in the MM200.  No selector toggle switch required.  You'll also need to make all the external connections shown in the connection layout for the AEC 200-1.Personally, I think you'd be way ahead of the game to just locate a Spoolmatic 1 that was designed to be a direct connect to your early MM200 and sell the Airco setup IMO.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Duane, I was hoping you'd weigh in here- it's obvious to anyone lurking around this forum you know these machines inside and out and have elegant solutions for pretty much any problem.Picked up the Airco after digging for an SM-1 for a week- have an alu job coming up this weekend and had to pull the trigger, so to speak.  I must say, the fact that Profax still mfgs and supports the model is appealing in this age of planned obsolescence (the makers of the blue boxes being no exception here) and I don't mind the workout from hefting the thing   A talented and learned welder sold me the kit at a good price, and it sure does spray nice.  Tips and other parts are cheap and readily available, and the duty cycle is no joke.  As a bonus, the orange FG enclosure looks great on the blue MM.Got it hooked up tonight- the box is pretty much the same as the current (non-solid state) Profax box, as far as I can tell.  Badged Esab, it has 115VAC in going to a stepdown transformer, rectified to 24VDC.  A relay, a big resistor, and a 5A fuse, and that's pretty much it.  The gun send back 8 wires to a bus strip, 2 of the 3 wires coming back from the wire speed pot on the gun are jumpered, and of the 6 that go into the box, 2 go through the relay to trigger the DC voltage for the gun motor, and 2 pass through the circuitry and head out to leads i connected to the 4 gun pin trigger on the Miller (only 2 pins used) to make CR1 and the contactor go.So hooked it up just like that and let the drive roller pressure off in the machine and tested it out- quite sweet.  I must have gotten too ambitious, though, and wanting to figure out if I could wire in a toggle to turn off CR2 to stop the drive motor and gas solenoid in the box, I jumpered pins B and D on the SM-1 Amphenol and promptly blew what I think was D10 on CR2.  Oddly, CR2 not working after that didn't seem to affect anything- drive motor still ran, solenoid still worked???  Gonna dig around for a replacement 1A 400V diode tomorrow.From what I can tell, the easiest solution may be to wire the 115VAC transformer to the fan circuit (always on) and get a 6 or 8 pin Amphenol to install on the from panel.  Put a toggle to switch the gun trigger between the Tweco and the Airco, and another to turn off the drive motor and gas solenoid in the MM, assuming I can figure that out.Your help is appreciated, of course! Thanks in advance, Josh  Originally Posted by duaneb55Well the AH20-E gun operates off arc voltage whereas the early MM200 spoolgun circuitry is configured for the direct voltage operation of the Spoolmatic 1.Presuming the 115V weld control box you have for the AH20-E is the equivalent to the Profax AEC 200-1, you'll need to use that in order to get the Airco to work off your MM200.The only pins you'll need to use in the 4-pin SG receptacle on the Miller are B and D to energize CR2 within the MM200 that will activate the main weld output contactor WITHOUT running the wire feed motor in the MM200.  No selector toggle switch required.  You'll also need to make all the external connections shown in the connection layout for the AEC 200-1.Personally, I think you'd be way ahead of the game to just locate a Spoolmatic 1 that was designed to be a direct connect to your early MM200 and sell the Airco setup IMO.
Reply:You're working with the wrong 4-pin receptacle on the MM200.You should not be connecting to the 4-pin gun trigger Amp unit (RC1) but rather the 4-pin Amphenol in the lower right hand corner of the faceplate (RC3) that is for spoolgun control.Pin locations B and D in the Amphenol will energize CR2 that in turn activates the main weld output contactor without powering the MM200 wire feed drive motor or machine gas valve.  This is what you need to be doing.  CR2 is the one you need to a activating and NOT CR1 for spoolgun operation.I have no idea how you rigged the toggle switch but based on your description my guess is you created a direct short to CR2s coil which may have damaged flyback diode D10 and possibly CR2s coil and even fried bridge rectifier SR2.  This may come across as a little harsh but it's time to step back and get an understanding of how the machine functions and no more poke-n-hope modifications that can really damage something.How are you connecting weld output from the MM200 to the weld control box and AH20-E?MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Duane- not harsh at all. I was thinking I was doing a bit better than poke-and-hope but results appear otherwise. It's clear to me now my understanding of the CR1 / CR2 relationship was incomplete. The Airco box does appear to duplicate many functions, if not all, of the SM circuit in the machine- I don't wish to limit the future use of the machine to just the Airco so I'm trying to figure out how to install the box and a ampherol plug for the gun without making the SM plug and circuitry inoperable. I can power the Airco transformer from the 115v taps in the MM used for the fan, I'm just confused how to connect the box to the machine to disable the CR1 circuit. I'm not opposed, of course, to simply adding a dpdt toggle to the face for that function. My thought in jumpering B and D on the SM plug was that it would do just that, and the only casualty seems to be D10 so I'm out 20 cents
Reply:OK.  Let me try this again.Forget about CR1 in the MM200.  Remove it completely from your mind.  Also forget about adding a selector toggle switch as it is not necessary as I stated before.B and D in the 4-pin Amphenol receptacle in the lower right corner on the front of the MM200 connect - in your case thru the two small gauge leads from the weld control box terminal strip studs #1 and #2 - to activate CR2 in the MM200 to energize the main contactor to deliver weld output to the spoolgun power receptacle in the lower left corner of the front of the machine while at the same time NOT activating the MM200 wire feed motor or gas valve.  That's how it's designed to work with a spoolgun.As for the 115VAC to power the control box, just plug it into a regular household duplex outlet in your shop and save yourself the trouble of having to add a different receptacle/plug arrangement on the MM200.To connect the AH20-E weld power cable to the MM200 follow the diagram in the .pdf file below with the understanding the weld cable plugs into the spoolgun weld output outlet in the lower left corner of the MM200 face plate.  If it didn't come with the control box and gun, you'll need a power/gas adapter shown in the diagram.AEC 200-1 to CV Power Source Setup.pdfAll that said, what is the SN of your MM200 and the specific model # of the weld control box that came with the AH20-E?Got any photos of the pieces?MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Gotcha, Duane. CR-1 has become invisible to me whenever the spoolgun is involved. Serial number on the MM is JC634971, the Esab box looks to be mod. AHC-S1, but the label is pretty beat so that may not be right. Can't post pics from my phone so gimme 20 minutes and I'll get to my computer to upload them. I really appreciate your help and would like to call your local pub and pay a tab for ya Sent from my iPhone using Tapatalk
Reply:To clarify how I was using the box & gun- and not ideal, note- the Esab box has the 8 lead connector bus on one side, and the 8 wires from the gun come to that.  Two of the three from the pot on the gun end up jumpered together (see pic) and the remaining six run into the box.  Coming out of the box are the 115VAC plug, and a short run of 16-2 cable.  As per instructions from the seller, I connected the two wires from that cable to the gun trigger plug (RC1) to test to see if that was in fact the contactor energizer, and it worked, while of course still running the drive motor and activating the MM's gas solenoid.  I now understand that RC2 serves the function of activating the contactor when a spoolgun is connected, without powering the drive motor or solenoid, but I'm having a hard time wrapping my head around how what happens at different RC3 pins affects whether RC-2 or RC-1 energises the contactor W.Last edited by squaretaper; 10-15-2014 at 07:10 PM.
Reply:And looking at the SM-1 manual schematic and the MM200 schematic (http://www.millerwelds.com/om/o1210g_mil.pdf and http://www.millerwelds.com/om/o1303e_mil.pdf) I'm seeing that the trigger on a SM-1 should provide continuity between pins B and D, but that looks to put reverse voltage across D10 (which I saw in action).  Now I'm even more confused.
Reply:But even that voltage shouldn't do anything to the diode (had to lookup flyback diode; thanks for that lead). Checked voltage at pins B&D again, showing 32.2v. Replaced the diode, connecting the Esab box's control whip to B&D again popped the new 400v diode. Sent from my iPhone using Tapatalk
Reply:I understand how the AH20-E is wired and works but a couple clarifications.  The 4-pin Amphenol is RC-3.  RC stands for ReCeptacle.  The relays we've been discussing are the now ignored CR-1 and CR-2 that we want the ESAB box to control not RC-1 (MIG gun trigger) and RC-2 that are other receptacles on/in the machine.  CR stands for Control Relay.Can you confirm voltage at B and D is in fact DC and not AC?  If AC, bridge rectifier SR2 has at least one shorted diode.Unplug the box control from RC-3 and see if the two leads are just making continuity when the AH20-E trigger is pulled or if there's voltage present there.  It's possible the box circuitry was modified to provide a 24VAC or 115VAC contact closure signal depending on what machine it was hooked to.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Whoa. Switched the multimeter to AC check voltage and it reads 65vac. It's a crappy meter, but I'm not sure if getting the (more expected) 32vcd reading when set to dc means it is reading just one side of the actual ac voltage sine?Sent from my iPhone using Tapatalk
Reply:Checked voltages at SR2. 35vac at wires 30 & 33 (expected). 67vac across wires 34 and 35. Sent from my iPhone using Tapatalk
Reply:Oh, and sorry I mixed up RC and CR before- I do understand that much; was just hurriedly typing on my phone Sent from my iPhone using Tapatalk
Reply:Disconnected SR2 and checked continuity to see if there was a blown diode, and it seems to be ok- nothing shorted, nothing blown. Continuity direction for each diode is correct. Sent from my iPhone using Tapatalk
Reply:Originally Posted by squaretaperWhoa. Switched the multimeter to AC check voltage and it reads 65vac. It's a crappy meter, but I'm not sure if getting the (more expected) 32vcd reading when set to dc means it is reading just one side of the actual ac voltage sine?
Reply:Also borrowed a known good multimeter. Getting just 38vDC now at pins B and D on RC3. Also disconnected wires 38 and 34, jumpered B and D, checked voltage across 38 and 34: 38vDC. Checked polarity of diode, correct. Sent from my iPhone using Tapatalk
Reply:Forgot to ask earlier - with diode D10 disconnected, does CR-2 energize when you jumper B to D?MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Duane! You're amazing- with positive probe in D- wire 38 and negative in B- 35: -32vdc.   Looking at the continuity of the diodes on SR2- and I'm checking resistance both ways to determine this- I see forward bias with red probe on the pin 34 was on to the pins 30 and 33 were on (4k ohms, which seems high, but .0L with black on the 33 pin). Same forward bias with red on the pins 30 and 33 were on from the pin 35 was on. Looking at the schematic, and having checked my meter's continuity polarity on a spare 1n4004, it does appear the polarity has been switched. Seems bizarre, as all the wiring looks factory. And yes, cr2 does energize and short 34 to 37 when B and D are jumpered...Sent from my iPhone using Tapatalk
Reply:Now we're getting somewhere. Switch wires 34 and 35 at SR2 and replace diode D10 with band (cathode) toward 34 and it shouldn't blow anymore when you jumper B and D or activate CR2 with the EASB box control leads you once had connected to MIG gun trigger receptacle RC1 connected to B and D.If/when that all checks out can you get the AH20-E weld power cable connected to the spoolgun power outlet on the MM200 and gas connected to your argon tank?Double check that MM200 SN.  It comes back as no good.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:I know the serial is weird- I tried searching it on miller's web site. It's stamped on the faceplate, though...Sent from my iPhone using Tapatalk
Reply:And I'm thinking I should leave the spool gun power running off the 115vac to 24v step down in the box- as the power provided by the MM is hypothetically 36vdc and actually more like 32-33vSent from my iPhone using Tapatalk
Reply:That would be my recommendation.  Just put a household plug on the two 115 leads and plug it in a shop outlet as I suggested before.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!Duane- she's all wired up, tested, and ready to spray alu. I owe you a great debt- seriously: PM me your address and I'll put something on the mail for ya Pics show how I wired the board from the Esab box into the space left in the MM for the SKP-35. Controller is powered from the 115VAC taps from the transformer, with an in-line fuse and a toggle on the front panel to turn on or off power to the box to prevent accidental triggering of CR2 and the contractor by the spoolgun. Probably will replace that with a DPDT switch also controlling the torch trigger- the idea is to have both the spoolgun and Tweco gun plugged in and ready to go. 8 pin Amphenol is installed on the front panel just to the left of the SM-1 RC3, and taps taken off 38 and 35 connected to the contractor trigger circuit off the Esab box's relay. All functioning as hoped. Thanks again, and if anyone has similar projects, feel free to hit me up- I took plenty of pictures and notes during the process. My next MM project will be to replace the existing cap bank (all stock 9000 uF) with new 15000s like Duane did. She welds so sweetly now, can't wait to see what she'll be like after the upgrade. Last edited by squaretaper; 10-17-2014 at 05:56 PM.
Reply:I wondered where you went.  Now I know.My assistance focus was to get the ESAB control connected to the MM200 thru RC3 as a result of your stated desire to not "limit the future use of the machine to just the Airco" but you've obviously been successful in your desire and effort "to figure out how to install the box and a ampherol plug for the gun without making the SM plug and circuitry inoperable.".With the ease at which it would be to connect the ESAB control to the MM200 RC3, I personally would likely not take the route you did but at the same time I can understand why you would want to - if that makes sense.Good job. Did you get the motor "drift" issue resolved for the MM200 MIG gun?  The problem could be a failed brake resistor R1 that sparkness mentioned in post #3 or bad contacts in CR1 for the "brake" circuit.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Can't quite make it out in our photo - what are the voltage ratings listed on the faceplate of your unit?  200/230V or 230/460V?If 200/230, the input power jumper is in the 200V position.If 230/460, it's in the correct location for 230V operation and based on your previous B to D RC3 voltage readings my guess is it's 230/460V and all good.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Duane- I know wiring the box into the MM is perhaps overkill, but I like the idea of making the machine as clean as possible. The esab box had the 8 wire bus screwed on the outside, making me think that it wouldn't take much to accidentally short or damage the control wires from the gun lead. The Amphenol connector makes me feel like the gun/machine connection isn't just cleaner, it's safer and stronger. One less cord running across the floor, as well, with the controller running off the machine's internal 115v circuit. I'm running off two hot legs on my shop's 3ph, hypothetically 208vac, on my meter its more like 204-205 at the plug, hence the jumper on the 200 setting (200/230 machine). The brake circuit fix got back burnered- had to get the spoolgun running for a few alu jobs this weekend, but it will be the next thing I do after delivery, perhaps along with the cap replacement. Gotta hunt down a source for the 15000s... I'll keep ya posted! Sent from my iPhone using TapatalkLast edited by squaretaper; 10-17-2014 at 08:26 PM.
Reply:I wouldn't call it overkill.  I completely understand your logic for doing so.Never thought about the 3-phase 208V possibility. eBay and http://www.tedss.com/ are usually good sources for caps as well as some surplus outlets.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!