AIRCO Heliwelder IV

Hi,

I am a beginning TIG welder. I have experience with stick and wire. I was given an old Airco Heliwelder IV. It is the 300A version with a water cooled torch and foot switch/amperage control. The code is 0665, the serial is MH10190, and the stock is 1341-0176.

The HF, the footswitch start, and the post flow all work fine. The problem with the system is in the amperage control. The output is the maximum of whatever range is selected (low-med-high). This is true for both the panel setting as well as the foot control. Both the panel potentiometer as well as the footswitch potentiometer feed into a PC board which the block diagram on the panel schematic calls a "Reactor Board". I shot gunned all the high amp parts, the thyrister and bridge rectifier and a couple of transistors. I then sent the whole reactor assembly to a company who repairs obsolete equipment. I labeled all of the connections before I sent it out. When it was repaired and sent back there were wires terminated differently than when I sent it to them. The board had tell-tale signs of previous repair before I sent it out. I am now unsure if the thing was connected properly as I was troubleshooting it. The block diagram is not detailed to the point that I could tell how to connect; there is a vacant terminal on the PC and a extra wire. I do not want to cook the $300 PC or anything else for that matter.

Does anybody have an old Heliwelder who could help me out with some wisdom or pictures or advice??

Sorry for the long intro, I have been tinkering with this for some time. Thanks in advance to anyone stepping up!

Lou

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Originally Posted by machinewbie

Hi,

I am a beginning TIG welder. I have experience with stick and wire. I was given an old Airco Heliwelder IV. It is the 300A version with a water cooled torch and foot switch/amperage control. The code is 0665, the serial is MH10190, and the stock is 1341-0176.

The HF, the footswitch start, and the post flow all work fine. The problem with the system is in the amperage control. The output is the maximum of whatever range is selected (low-med-high). This is true for both the panel setting as well as the foot control. Both the panel potentiometer as well as the footswitch potentiometer feed into a PC board which the block diagram on the panel schematic calls a "Reactor Board". I shot gunned all the high amp parts, the thyrister and bridge rectifier and a couple of transistors. I then sent the whole reactor assembly to a company who repairs obsolete equipment. I labeled all of the connections before I sent it out. When it was repaired and sent back there were wires terminated differently than when I sent it to them. The board had tell-tale signs of previous repair before I sent it out. I am now unsure if the thing was connected properly as I was troubleshooting it. The block diagram is not detailed to the point that I could tell how to connect; there is a vacant terminal on the PC and a extra wire. I do not want to cook the $300 PC or anything else for that matter.

Does anybody have an old Heliwelder who could help me out with some wisdom or pictures or advice??

Sorry for the long intro, I have been tinkering with this for some time. Thanks in advance to anyone stepping up!

Lou

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Still working on this? I've had a bad experience with repairing one of these several years ago (although I finally got it). There's also one of these machines sitting in my parents' garage, and the board from it is on the shelf in my garage. (don't get excited, the board is bad). Anyway, I may be able to help with the connections. SOMEWHERE I have a book on them with a machine schematics, and a partial schematic of the board that I drew myself, although God only knows if I can even find that book. The one that I had trouble with, I struggled with a problem similar to yours for DAYS, and it ended up being a simple 5-minute fix. This has been between 12 & 15 years ago, but I still remember it pretty well. I even labeled that section of the book: "Heliwelder IV, Machine from Hell". :)

Hi Jim,

Thanks for responding. I have followed your threads for some time now.

I took a leap of faith and made the connection of the extra wire to the only terminal left on the PC board. I now have control of the amperage. However, it is of very low output. On the low and medium ranges it is unable to lay a puddle in 1/8" mild steel. On the high setting, the pedal responds but for a 300 amp machine it seems very weak. I think there is something miss connected on the output, but going from the "block" diagram I cannot proceed any further. I was really happy that I did not let the smoke out of the newly repaired board!

I could still use any help by means of documentation or pictures or advice. I agree with you, it is probably a very simple fix, a five minute modification. I am just at the end of my capabilities with my current resources. There is absolutely no rush. I use the welders to help friends and family. The TIG is learning vehicle. It is not a business, mostly for my own pleasure!

Thanks,
Lou

Quote:

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Originally Posted by machinewbie

Hi Jim,

Thanks for responding. I have followed your threads for some time now.

I took a leap of faith and made the connection of the extra wire to the only terminal left on the PC board. I now have control of the amperage. However, it is of very low output. On the low and medium ranges it is unable to lay a puddle in 1/8" mild steel. On the high setting, the pedal responds but for a 300 amp machine it seems very weak. I think there is something miss connected on the output, but going from the "block" diagram I cannot proceed any further. I was really happy that I did not let the smoke out of the newly repaired board!

I could still use any help by means of documentation or pictures or advice. I agree with you, it is probably a very simple fix, a five minute modification. I am just at the end of my capabilities with my current resources. There is absolutely no rush. I use the welders to help friends and family. The TIG is learning vehicle. It is not a business, mostly for my own pleasure!

Thanks,
Lou

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I'll try to locate that book this week, but no guarantee I'll find it. I'm sure you probably got the right things on that board, but the thyrister you mentioned is actually a Triac, not just an SCR, so therefore will pass both halves of the AC waveform on the control voltage. (It's kinda an oddball circuit compared to other welders). I do recall from memory that the AC voltage from the windings to that triac is approx. 80VAC. Once it passes through the board circuit, it is fed to a bridge rectifier and then to the control winding. This might be a good initial test. The machine I fought with all those years ago initially had a bad bridge and there was where I screwed up. I stuck a new one in, and ASSUMED that the red wire was positive and the black negative. Ended up that this was backwards, but I was blind to it. The board monitors this voltage (but the polarity must be correct). The voltage from this circuit, as well as the control voltage from the potentiometer on the panel/pedal are fed into different parts of the LM324 OP-AMP on the board which in turn, controls the firing circuit for the triac. Maybe some on that will give you a good starting point while I search for that manual. LMK if you make any progress in the meantime.
Later,
Jim

If you are still working on this, I have hundreds of welder service manuals, including one for your machine. I just found this forum or I would have mentioned it sooner. Let me know if you need a copy.
thedoctor

Hello,

I just came across this website and noticed you replied to another gentlemen regarding his welder. I have an old Airco 300 Heliwelder IV machine with a similar problem of no current control. I have just ordered a new reactor pwb for replacement and apprehensive to power the unit up. I need to know and to verify what color wires go to the 25 Amp bridge rectifier mounted directly above the reactor board. There are four wires; colors are blue, white, red & black. I know the white & blue go to the AC terminals. Would you know the correct wiring for the red & black leads? I have a picture of the wires in question. I would greatly appreciate your comment or any suggestions. What are the possibilities that you may still have a schematic on that particular circuit pwb or the machine?

Thank you much for your time.

Quote:

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Originally Posted by tadream

Still working on this? I've had a bad experience with repairing one of these several years ago (although I finally got it). There's also one of these machines sitting in my parents' garage, and the board from it is on the shelf in my garage. (don't get excited, the board is bad). Anyway, I may be able to help with the connections. SOMEWHERE I have a book on them with a machine schematics, and a partial schematic of the board that I drew myself, although God only knows if I can even find that book. The one that I had trouble with, I struggled with a problem similar to yours for DAYS, and it ended up being a simple 5-minute fix. This has been between 12 & 15 years ago, but I still remember it pretty well. I even labeled that section of the book: "Heliwelder IV, Machine from Hell". :)

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With information provided by thedoctor I was able to correctly connect the reactor PCB and verify operations with test points and performance parameters. I sent the PCB to Radwell International and they repaired it. It has returned and the welder seems to be working. I have friend who is an expert TIG welder who will confirm ops for me.
Thanks Doc!

Quote:

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Originally Posted by thedoctor

If you are still working on this, I have hundreds of welder service manuals, including one for your machine. I just found this forum or I would have mentioned it sooner. Let me know if you need a copy.
thedoctor

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I have an Airco 150 Amp AC/D? MSM Heliwelder - Stock # 1341-0245, Serial H11051145 that I am looking for manuals and the remote HF Control switch. If you have thses items or know where I can receive them, I would greatly appreciate any help you might be able to give me. Thank you in advance, Drew.

Here is a link to a few welder manuals for Airco Welding Machinery.
http://www.industrialmanuals.com/airco-m-117.php

Here is a link to many welder Operations manuals, Parts List, Maintenance Manual, Schematics

http://www.industrialmanuals.com/welders-c-68.php

Hello guys,

I have an Airco 300 AC DC Square Wave Welder High Frequency Intensity and a short circuit was made in the electronic boards. If you have the electronic diagram or an image of the circuit board that helps me discover the components, I'll thank you. You can send me an email to: [email protected]

I can send you photos of the electronic board with the components that exploded.

CODE: 1095
SERIAL: MH905039
STOCK: 1341-0290

Thank you in advance for your time and your help.


Regards,
Juan Restrepo
Phone: 415 828 7997

Hello! I have the same Airco 300amp Heliweld IV machine stock# 1341-0176 code #0470 and ser# MG911065 and would like to find information/manuals aswell Thanks!

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Originally Posted by woodstock269

Hello! I have the same Airco 300amp Heliweld IV machine stock# 1341-0176 code #0470 and ser# MG911065 and would like to find information/manuals aswell Thanks!

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I know this is an old post but wondering if anyone has found a manual for these machines. I just picked one up with pulse installed.

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Originally Posted by Docdar

I know this is an old post but wondering if anyone has found a manual for these machines. I just picked one up with pulse installed.

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Anyone here??