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Central Machinery Mini Lathe popping fuses

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Franko

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#1
The other day I needed to make a part that was a bad fit in my 12x28 lathe.
I chucked it in my Harbor Freight 7x16 mini lathe. When I turned it on the switch lighted up but when I gave it the gas nothing happened.
I checked the fuse and it was blown, so I replaced it. I turned it on and gave it the gas and the fuse instantly popped.
I rinsed and repeated with the same result.

I opened it up and took a perfunctory look at the control board but could see no signs of arcing paths.
I didn't remove the board and examine it with a microscope.
The wiring that I could see all looked good.
The lathe hasn't been used much. I doubt it has 30 minutes of run time since I got it new.
Whatever happened, happened when it was just sitting there plugged in and turned off.

I've had a board go out on my Grizzly mill due to a power surge, probably during a storm. I'm guessing maybe the same thing happened to the Mini Lathe.

Has anyone else had a similar experience?
Does it always have to be the control board?
 

Z2V

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#2
Can you electrically disconnect the motor and put another fuse in it? I’m not familiar with that lathe. Does the control board have plug in connections for the different switches? If so disconnect everything except incoming power and see if it still blows the fuse. If not, start plugging or connecting the switches back one at a time until the fuse blows again. Start a process of elimination. Unfortunately, it will likely be the control board as luck would have it.
 
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royesses

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#3
Try setting the forward/off/reverse switch to off. Then if it blows the fuse it isn't the motor. If it doesn't blow the fuse its not the control board or wiring.

Roy
 

markba633csi

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#4
Hi Franko, you might check out Pete's website:
olduhfguy.com
 

Franko

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#5
Try setting the forward/off/reverse switch to off. Then if it blows the fuse it isn't the motor. If it doesn't blow the fuse its not the control board or wiring. Roy
It got weird, Roy. Now it doesn't blow the fuse whether the switch is forward, reverse, or off. The motor does not start, either. The power switch lights up even with the fuse blown or removed.

Hi Franko, you might check out Pete's website:
olduhfguy.com
Thanks, Pete. That looks like a useful link.
 

Franko

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#6
Can you electrically disconnect the motor and put another fuse in it? I’m not familiar with that lathe. Does the control board have plug in connections for the different switches? If so disconnect everything except incoming power and see if it still blows the fuse. If not, start plugging or connecting the switches back one at a time until the fuse blows again. Start a process of elimination. Unfortunately, it will likely be the control board as luck would have it.
It is tucked in a tight corner and I'll have to move it to a workbench to reach, see, and/or access everything. I might be able to disconnect the motor at the board, though I think turning it off at the forward/reverse switch probably ran the necessary test.
 

royesses

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#7
Sounds like you may need to get a voltmeter in there to check for power at the motor. It might be that the mosfets finally opened up and are no longer sending out current to the motor. LMS has a sort of schematic, actually a wiring diagram on their web site. You can check for input / output from the controller. also you could try supplying 12 volts to the motor to see if it spins. A car battery should spin it up. LMS sells the mosfets but there might be other damaged components. Might be worth a try to replace the mosfets if the motor tests good. I've also seen the switches go bad and cause the motor to stop working. My speed control has a switch that went bad.

If you look at the wiring diagram the lighted switch has a bulb that is connected to both sides of the 120 volt line so when it is turned on the bulb will light even if you disconnect both wires from the controller. It just indicates that power is being supplied to the switch when the switch is closed.

I keep my equipment unplugged when not in use. The lightning here in OK is similar to what Texas sees. A tree outside my apartment when I first moved here was struck one morning. I watched as lightning arced over the cable tv and computer wires in my living room. It took out my cable modem and computer and my 5 channel sound system but not my 2 high dollar plasma tv's. It just seemed to randomly destroy electronics and leave other stuff alone. It even destroyed a battery powered clock on the wall. When I purchased my home the first thing I did is install a whole house surge protector.

Roy
 
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Franko

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#8
Thanks, Roy. I'm starting to think I need to unplug my lathes and mill when not using them. This is the second time something like this has happened. I've never had anything surge out in the house. I'll look into a surge protector.

My switch only lights when it is on.
 

Usermanual

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#9
My Central Machinery lathe started drawing too much power for the factory fuse as well. I want to say it was a 5A fuse and I replaced it 2-3 times with identical results to yours. (replace, pop, replace, pop) I jumped up to a 10A fuse about a year ago and have experienced zero issues with the machine since then. I may be running the motor a bit harder than it's ideally rated for, but it hasn't shown any outward signs of fatigue due to the extra 5A allowance.
 

Franko

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#10
I think mine has a 4 amp fuse. I tried an 8 amp, which blew just as fast.
 

Chip Hacket

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#11
Franco reading the thread it sounds to me like the problem is on the motor driver portion of the board. “Mosfets”. Can’t be sure though. Unfortunately the board will probably need to come out to fix what ever the problem is. I’m not familiar with that setup but the best part usually is removing the board or trying to shoe horn it back in with fat fingers blocking your view.

If it helps the mosfet probably didn’t blow during a storm but when you switched it on.

I’ll be glad to help where I can.

—Chip
 

Groundhog

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#12
I have a board (and maybe some other associated stuff) if needed - check your PMs
 
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