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Thread: Blown Fuse

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  1. #1

    Blown Fuse

    Tom,

    I got my compressor in the UPS on monday. I hooked it upto 85 PSI (I have a 20 CFM compressor). I filled my tank once and it worked fine....It shut off at 4000PSI

    I turned the compressor on to fill the tank again before i went to work today.....It shut off at 3000 PSI for some reason. I turned the switch on and it blew the fuse. I changed the fuse and turned it on and it started to move......acted like it was under load (No tank connected to compressor) and then all of a sudden it stared to pin normal RPM again...........any ideas? The thing is brand new......and im running 85PSI

  2. #2
    Join Date
    Oct 2000
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    Chicago
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    5,951
    We had one report of the wire nut coming loose on the power cord and grounding out. UNPLUG, take off the cover, and see if there is a blue wire nut up by the fuse. Also disconnect all the hoses and see if you can turn the crankshaft by hand.

    AGD

  3. #3
    Quote Originally Posted by AGD
    We had one report of the wire nut coming loose on the power cord and grounding out. UNPLUG, take off the cover, and see if there is a blue wire nut up by the fuse. Also disconnect all the hoses and see if you can turn the crankshaft by hand.

    AGD

    The wire nut is still on the wires and its tight. The crankshaft is VERY hard to turn by hand. I noticed that the top aluminum tube thing rocks between the shoulder that is machined on it and also the snap ring on every cycle.....Seams like that would wear the snap ring groove.
    Do you think something is out of alignment? Any ideas on what needs to be done.

  4. #4
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    Chicago
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    Ok then we need to check to make sure the pistons are running freely in the cylinders. There is a connecting rod that goes from the crankshaft to the small aluminum block with the arm that trips the switch. Take a small screw driver and carefully work off the push on nuts that keep the connecting rod on the shafts.

    Once your connecting rod is off, see if you can push the rods in and out of the cylinders. Then test the crankshaft rotation. The rods will take some effort because of the orings but you should be able to get a feel for it.

    With the connecting rod off, try turning the motor shaft by hand and see if it turns freely and rotates the crank. Report back here.

    AGD

  5. #5
    Quote Originally Posted by AGD
    Ok then we need to check to make sure the pistons are running freely in the cylinders. There is a connecting rod that goes from the crankshaft to the small aluminum block with the arm that trips the switch. Take a small screw driver and carefully work off the push on nuts that keep the connecting rod on the shafts.

    Once your connecting rod is off, see if you can push the rods in and out of the cylinders. Then test the crankshaft rotation. The rods will take some effort because of the orings but you should be able to get a feel for it.

    With the connecting rod off, try turning the motor shaft by hand and see if it turns freely and rotates the crank. Report back here.

    AGD

    I took the connecting rod off. Motor and chain drive spins nice and free but cylinders are bound up.........I bet i was putting 50 lbs of force on the end of the shaft and she wont move.

    Jay

  6. #6
    I got bored so i took the thing apart.

    Here is what i found.

    The cylinder with the small shaft coming out of it is fine and the shaft moves in and out nice and smooth.

    The cylinder with the large shaft was bound up. The grease inside the unit turned into a very thick and sticky mess. about 1 inch of the end of that shaft that goes in the cylinder has light scoring on it. I did notice the black plastic tube thats about an inch long fits over the shaft pretty night. The short one with the holes in it slides over the shaft nice. all the orings look good. My shop compressor has a water trap and a filter on it and im putting 85 PSI into the shoebox. Do you think the grease turned sticky because of the heat its subjected to?

    What should i do Tom? I know i can clean the thing out with alcohol, regrease it and put it back together but i would like to know what went wrong?

  7. #7

    Bad Motor.

    To TK, Hi Got the compressor Tues, went to set up today (Thur. 4 pm), flip switch blew fuse instantly. Motor just hummed for second. Removed chaindrive same effect, removed motor from unit, motor itself is binding internally. Could not turn motor shaft by hand, after a bit of trying able to rotate, but it is grinding like the armature is riding on the windings.
    There was no external damage to shipping box nor can I find anything on the unit itself.

    Note: If you were to drill a access hole through the alum. and shield plate for access to the lower left motor bolt, It would be a lot simpler to adjust chain drive/ replace motor. Bit tight to get at that bolt.

    Thanks, Chris Thode
    Adendum:
    Per motor information booklet, tried to readjust by tapping end caps, got shaft almost completely free, but no go when power applied, just the hum.
    Last edited by blades; 07-22-2010 at 05:08 PM.

  8. #8
    Join Date
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    Blades,

    WOW! that is a first! Something must have fallen into the motor and jammed it. Do you feel comfortable taking the end caps off the motor? Its pretty simple and there is not much to go wrong. Let me know and I can walk you through it.

    Tom

  9. #9

    motor binding

    Hi. I did not pull the end caps completely I will do so now and report back.


    OK , Pulled end caps, I have a pic of what I think is problem, do not know how to post it here so will describe. The bearing cup is deformed by the motor shaft/ inside race of the bearing. It must have taken a perty good bounce in its travels as this area is deformed so as to rub on the inner bearing race. This applies excessive pressure to the armature between the bearing cups causing the binding when the four bolts are pulled up tight. The deformation looks to be only on about 1/3 of this area. I think I can get the Dremel tool in there to relieve that area.

    For whatever reason I am not able to post picture keep getting error code.
    Last edited by blades; 07-22-2010 at 06:21 PM.

  10. #10
    Really bad storm here now, Lost power couple times. Need to get home if it has not floated away. later Chris

  11. #11
    Join Date
    Jun 2009
    Location
    Kentucky
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    4,146
    Use http://photobucket.com/ to host pics, then link them.

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