Need help with air compressor....

[JHardgrave]

Hey guys, hoping one of you has delt with a similar problem in the past, I have a 60 gallon vertical compressor with an inline twin cylinder pump up top. It has worked fine for a long time, but now it does something funny. When you kicked it on before, it would just jump straight to operating rpm's. Now, especialy in the morning when you fire it up it sounds like its "idling" at first and slowly comes up to full throttle. There is no speed control on this thing, its on or off. How and why is it having to accelerate up to speed over about 5 seconds? An employee suggested maybe bad brushes in the electric motor? Im at a loss.

[Reef Drifter]

Ours at work does it when the belt gets loose

[Overkiller]

Check your capacitor(s)

[JHardgrave]

I went out and tugged on it and it felt pretty tight. I guess Im just not going to worry about it as its not realy causing an issue, just sounds kinda funny. Thank you for the suggestion

[JHardgrave]

overkiller, I was unaware it even had capacitors. How would I go about that?

[Overkiller]

I'm guessing it's a 220v compressor.... If so there should be a cover or covers screwed to motor. Underneath will be big capacitors to give it the boost to get going. Sounds like one is out and if so motor failure will be along shortly, it'll heat up and work too hard getting going and eventually poof. Kill the juice and pull the covers, a decent multimeter will allow you to check for capacitance however in my experience if one is blown it's generally obvious. Deformed case, stinky burned fish oil smell ect. Careful the capacitors can hold a charge and hit harder than a cup of coffee if they discharge on you. The fun part is often finding the replacement, there are so many varieties finding the right one is often a pita. I can recommend some places to check if you need. If your compressor is 3 phase disregard everything I just said. Let me know if you need help, I can make a detour out your way tomorrow and give it a once over. Capacitors are much much cheaper than a motor.

[Curmudgeon]

I'm guessing it's a 220v compressor.... If so there should be a cover or covers screwed to motor. Underneath will be big capacitors to give it the boost to get going. Sounds like one is out and if so motor failure will be along shortly, it'll heat up and work too hard getting going and eventually poof. Kill the juice and pull the covers, a decent multimeter will allow you to check for capacitance however in my experience if one is blown it's generally obvious. Deformed case, stinky burned fish oil smell ect. Careful the capacitors can hold a charge and hit harder than a cup of coffee if they discharge on you. The fun part is often finding the replacement, there are so many varieties finding the right one is often a pita. I can recommend some places to check if you need. If your compressor is 3 phase disregard everything I just said. Let me know if you need help, I can make a detour out your way tomorrow and give it a once over. Capacitors are much much cheaper than a motor.

Good advice from a bending unit.

[JHardgrave]

Ok, pulled the little cover off, this is what I see. More or less a junction point for the incoming power wires. The motor is single phase 220 by marathon. Do I have to remove the entire rear of the unit to see capacitors? my only experience with capacitors is when me and my buddies built a ridiculous van de graaf generator and used 250 glass jars with foil and salt water to make a 4 foot spark... am I looking for a little tube deal? If you had time tomorrow, when could you stop by? If this thing breaks down, my shop screams to a hault real quick.

[Overkiller]

I'll stop by tomorrow but the capacitors should be under covers on the side of the motor. Does your shop have 3 phase service? May be a good time to consider putting a 3 phase motor on that dude. I'll call when I'm on the way.

[Curmudgeon]

I'll bet the caps are under the lump on the upper right corner of the photo.

[JHardgrave]

Curmudgeon, your right about the caps, but the capacitors checked out fine. We believe now that this compressor running 40 hours a week in a cloud of sanding dust is eating itself alive. Im going to jack my own thread and ask if anyone has a used 3 phase compressor they would part with?