AEAD200LE open circuit voltage too high?

[nvce]

Recently picked up this old soldier at auction. With a little effort(and cash) I got the engine running nicely and found the generator side working great. The unit didn't have leads and I hesitate to lay out any more money if the weld side won't work. When I switch from power to weld and kick the throttle to weld speed (it's not automatic) and check the voltage at the dc work lead plugs, it shows almost 135 volts. I understand that correct ocv is 80 volts. I have the owners manual from the miller site and the schematics have been helpful but need some help taking the next step on this. It's a former army unit on a neat trailer with some cool features added long ago in the motor pool. I really could use a portable welder at work. Any ideas what to do about this high voltage? Thanks

[Aeronca41]

Please post your serial number so we can look at the correct diagrams. Where are you located? Maybe you can borrow some leads. Does the plug on the work lead from your MM35 fit the weld power receptacles? I'm guessing it will but don't know. if so, you only need one more cable. Be careful-135 volts will obviously zap you. Have you measured frequency at the AC power outlet to verify correct engine RPM?

[griff01]

Recently picked up this old soldier at auction. With a little effort(and cash) I got the engine running nicely and found the generator side working great. The unit didn't have leads and I hesitate to lay out any more money if the weld side won't work. When I switch from power to weld and kick the throttle to weld speed (it's not automatic) and check the voltage at the dc work lead plugs, it shows almost 135 volts. I understand that correct ocv is 80 volts. I have the owners manual from the miller site and the schematics have been helpful but need some help taking the next step on this. It's a former army unit on a neat trailer with some cool features added long ago in the motor pool. I really could use a portable welder at work. Any ideas what to do about this high voltage? Thanks

Remember, terminology is important when conveying information. If I remember correctly, at least one model of the 200LE, has a receptacle that is indeed 135 vac. Do verify this as I could be wrong.

Griff

[nvce]

Thanks for the quick reply. The serial # is HG059928. This model has a 240VAC tap inside the cabinet as well as a 115VDC receptacle and 120VAC duplex on the front. Sorry for leaving out so much detail. I'll get hold of a shaft end tach on monday and confirm the engine speed then. Thanks again. Sean

[Aeronca41]

Good. Let us know. Meanwhile, I suspect a couple of people will be looking at the diagram. Just for info, while the shaft end tach is probably OK (I'm not an expert), the accepted method of verifying engine speed is measuring the frequency at the AC outlet. Generally set a little above 60 HZ with no load on the smaller machines like this-My Trailblazer 280NT gets set to 62.5 hz.

[nvce]

That'll be an easy check. This machine has a hand set throttle..idle, power and weld positions. A mechanical governor maintains speed under load. What would be the best way to confirm frequency at weld speed and what should the frequency be? Thanks. Sean

[Aeronca41]

If you have a digital multimeter with a scale marked HZ, just put the leads (carefully!) into the AC outlet and read the frequency. If not, you can get a Kill-A-Watt meter at Home Depot or even Harbor Freight. Just plug it in to the outlet and push the HZ button. I'm not sure of the frequency for your specific machine but others in the same size class are set to 62.5 HZ. If Cruizer sees this he may be able to confirm or correct that but I think you would be safe using that number.

[nvce]

Looks like my problems were due to engine speed. Adjusting the engine speed while watching hz on the multimeter brought the voltage at the ac outlet back in line. Replacing a bad bidge rectifier got the dc outlet going though can't think what I might need it for. There are two independently adjustable throttle stops for power and weld so the job was straightforward. Really surprised how a fairly small speed change at the crankshaft made such a big difference in frequency. A neighbor heard I needed welding leads and donated an old Airco dip/stick 160 with a good set of heavy leads attached so I should be welding soon. If anyone needs spares from that machine let me know (he says it welds but the wire drive gave out). Thanks aeronca41 for the great advice and thanks to miller for supporting this forum. Sean

[Aeronca41]

Super! Free fixes are wonderful! Glad it worked out so well. As to the use of the DC outlet-if you have any power tools that are marked AC/DC on the nameplate, you will find their universal motors work better on DC than AC. However, be sure it says DC on the tool or you may toast it. Back in the 50s and 60s many welders had no AC outlets, and we ran the universal motor drills and grinders all the time on DC.