# DOA Electric Motor Question



## 7HC (Aug 1, 2012)

Just finished assembling my HF 4x6 bandsaw and the motor doesn't work.  Doh!

Unpowered, the motor shaft spins freely, but when power is applied the motor hums and buzzes loudly and the shaft won't rotate.
It's being held magnetically rather than being physically locked.

A new motor is being shipped, but meanwhile I wonder if this a capacitor issue, either bad or wrong spec.
The motor is a 1HP (ha!) 120v and the cap is marked 250v, but I don't know enough to know if that's a problem.









As you can see, the cap is hard wired to the motor, although possibly there's a joint under the shrink-wrap.
If the cap is the issue, will it be safe to cut the wires individually using insulated pliers and gloves, then short it for safety?

Finally, if one is needed, how close a spec would a replacement cap have to be?

Thanks,

M


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## OldMachinist (Aug 1, 2012)

I'm no expert on motors but your capacitor is marked as a run capacitor so it only comes in to use under full load. The motor is either wired wrong internally or just bad. Was there any kind of wiring diagram for the motor under the cover?


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## 7HC (Aug 1, 2012)

OldMachinist said:


> I'm no expert on motors but your capacitor is marked as a run capacitor so it only comes in to use under full load. The motor is either wired wrong internally or just bad. Was there any kind of wiring diagram for the motor under the cover?



No, nothing under the end cover or capacitor cover.......this is an HF product so hardly surprising.

M


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## Old Iron (Aug 1, 2012)

That motor has the right cap in it, There run caps and it won't run or start with a start cap. Try giving the shaft a spin when you turn it on. If it starts then it will be the cap and good luck tiring to fine one.

Paul


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## 7HC (Aug 1, 2012)

sssfox said:


> It could also be that the contacts are dirty and not connecting so that the cap never gets into the circuit.
> That is usually the first thing I check because it is the easiest to fix.
> I am constantly amazed by what gets stuck between the contacts.



Ok, I stripped it down. There's no centrifugal switch therefore no contacts; the cap is soldered/crimped then heat shrunk to the connections on the windings, as is the the power feed coming from the on/off switch.  There are no connectors of any sort, so it'll be interesting to see how the replacement motor comes.:bitingnails:

Anyhow, I found the problem......the casing was cracked which had allowed the field windings, which are an interference fit, to drop down so they were no longer centered on the stator and they hit the bottom cover which broke several of the fine wires.
No sensible repair to be made there so I'll just have to wait for the new one to arrive.

Looks like I won't be cutting anything for a week or so either, so I'll spend some time tuning it and maybe giving it a coat of paint (it's a toss up between white and hammer finish grey); the dirty dull red/maroon in comes in looks like they just mixed up all the half empty paint containers they had in the factory and used that.  :nuts:

M


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## 7HC (Aug 1, 2012)

Froneck said:


> No Start Cap! I know they make motors without a start switch and start capacitor but they are usually reserved of low torque start applications like fan or blower motors. I hope your new motor is a better type!
> 
> Frank



So do I, but  have no real expectation that it will be be anything other than one more of the same, but hopefully without the crack in the casing.

Some regular connectors to connect the power feed would be nice too.

M


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## Pacer (Aug 1, 2012)

While youre waiting for that replacement it would be wise to look around for a better motor. While Chinese tools have improved pretty dramatically over the last few years, the motors - and electrics - are notoriously still pretty bad (as youve experienced).  Although, your motor is different from mine physically, maybe itll be better...

These are fantastic little saws, possibly the best buy in the whole line of tools, I just totally wore one out over the last 12-15 years. My replacement saws - supposedly - 1hp motor was so puny that it would only drive the saw in the lowest belt position, and even then, on a long cut would get very hot and I like to generally keep the saw in the middle setting. I had a spare 3/4hp Marathon in the cabinet and put it on the saw - whoa! what a difference. Note: you need a counter clock wise rotation motor - I had to change the Marathon over...


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## 7HC (Aug 2, 2012)

Pacer said:


> While youre waiting for that replacement it would be wise to look around for a better motor. While Chinese tools have improved pretty dramatically over the last few years, the motors - and electrics - are notoriously still pretty bad (as youve experienced).  Although, your motor is different from mine physically, maybe itll be better...
> 
> These are fantastic little saws...



I agree, they've got a good and long standing reputation, whichever name they have on the side.  
The only problem with a new good quality motor is that it'll cost more than the saw unless I can find a good used one.

M


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