Airco feeder stopped feeding

[Jim Shaper]

I've got an early 80's vintage airco feeder that had never been used prior to my acquisition about 4 years back. I've only put about 25# of wire through it and today the motor stopped working, but the gas solenoid still triggers.

There's no voltage at the motor leads.

Now this is a cobble job connection to my miller power supply. I had to use the 120v side of the power supply to feed a transformer to get the 42vac for the feeder, but it's been flawless for years (I've run high wire speeds for extended beads without issue in the past). Something that has had me puzzled was some porosity I was getting, but that could be due to my not running the welder much in a year or so, but the wire is still clean.

I opened it up and there's nothing overtly glaring. I was just doing some short 1" welds when it gave up.

I'll have to hook up my miller push-pull feeder and see if that's working right before getting too crazy with the airco.

Anyone have experience with this type of problem?

[Jim Shaper]

Just confirmed the miller feeder still works fine.

I may have screwed up when checking the motor leads earlier. I think I had it on AC, so I'll need to check that again for DC.

It's an Airco MED 20 btw

[macona]

The relay inside the feeder is bad. Think it is one of the ice cube style ones.

[Jim Shaper]

Thanks Jerry, I'll check them out. There's 3 relays in it IIRC.

Is it common for relays to give up the ghost like that? When I got it, it was showroom new.

[gnm109]

Thanks Jerry, I'll check them out. There's 3 relays in it IIRC.

Is it common for relays to give up the ghost like that? When I got it, it was showroom new.

Yes, relays can fail in all sorts of ways. A friend recently purchased a 1984 Mori Seiki CNC lathe. It has nearly 30 relays in one of it's two control boxes. It wasn't moving in the X axis. We checked all of the relays and discovered that two of them had the points stuck shut and one had corroded points. Once freed and cleaned up, the machine started moving properly again.

In your case, with no power, it's very likely that a relay either has a bad connection or the coil may be burned out. The nice thing about relays is they are easily diagnosed and they are relatively inexpensive.

Good luck.

[Jim Shaper]

Right, but I've been using it the last few days and now it just died. It's not corroded, that's for sure (stored in climate/humidity controlled shop). I also can't think of any reason for it to be stuck.

I know they're easy to check. I've just never had one fail for no reason. I was thinking it might be a capacitor that dried out - that seems more likely to me.

[gnm109]

Right, but I've been using it the last few days and now it just died. It's not corroded, that's for sure (stored in climate/humidity controlled shop). I also can't think of any reason for it to be stuck.

I know they're easy to check. I've just never had one fail for no reason. I was thinking it might be a capacitor that dried out - that seems more likely to me.

That certainly could also be an issue.

[macona]

The relay that starts and stops the motor shorts the motor armature to dynamically brake the motor when it stops. This can be quite a bit of voltage which can arc and weld or pit the contacts.

Also I have seen more than once the wire that connects the common terminal break off inside.