hf dust collector motor goes bust. now what?

[skamath]

hi guys,
right in the middle of a project my hf dust collector goes bust.

it wasn't like i was doing anything significant. i was just pulling some dust from a router table. the motor didn't die while running, but now it won't start.

the motor hums and is drawing awful lot of current since it dims my lights and trips my breaker after repeat tries.

i tried to turn the impeller by hand and see i can start the motor. the impeller sort of runs, but not really picking up speed. after some time the breaker shuts off.

any ideas? if the motor is bust what is a good replacement motor?

thanks,
sanjay

[Tom Slick]

The start capacitor is kaput. it is in one of the bumps on the outside of motor. They are replaceable.

[milanuk]

If you can dismount the motor from the DC unit and the impeller, take it to a local motor repair shop. They should be able to trouble-shoot it and repair it, or else offer you a suitable replacement unit. I think Tom is right; sounds like the start/run capacitor is T.U. It helps create a difference between the magnetic fields necessary to create a starting torque for the motor (single-phase AC). When the cap goes bad, the motor won't start on its own but may run if you give it a spin to get it rolling. The caps are fairly inexpensive and easy to replace - if you know what you're doing. Probably better to take it to someone who does it for a living to be safe.

[LCHIEN]

If you can dismount the motor from the DC unit and the impeller, take it to a local motor repair shop. They should be able to trouble-shoot it and repair it, or else offer you a suitable replacement unit. I think Tom is right; sounds like the start/run capacitor is T.U. It helps create a difference between the magnetic fields necessary to create a starting torque for the motor (single-phase AC). When the cap goes bad, the motor won't start on its own but may run if you give it a spin to get it rolling. The caps are fairly inexpensive and easy to replace - if you know what you're doing. Probably better to take it to someone who does it for a living to be safe.

the capacitor or maybe the centrifugal switch that controls it is quite often bad, some WD40 often puts it back working if stuck. It's located on the opposite end of the shaft.

[milanuk]

Good point. I've ended up replacing caps more often than the switch, but it's another 'likely suspect'.

[JR]

It's also worth checking the power switch. Those things melt all the time. The sypmtoms don't necessarily lead to this conclusion, but you never know.

JR

[LCHIEN]

It's also worth checking the power switch. Those things melt all the time. The sypmtoms don't necessarily lead to this conclusion, but you never know.

JR

he said it hummed and made noises so it was getting power and it's not likely the power switch.
OTOH, as JR says they have been known to go bad so maybe a half-bad switch could lead to malfunction.
However, humming but not turning are usually symptoms of the centrifugal starter switch/capacitor system not working right.

The starter switch is set so its closed when the motors not turning. The capcitor is shaded on one winding to unbalance the phase and get the motor turning the right way. after it gets up to speed a weight pulls the switch open so that the starter capacitor is disengaged and not stealing current. In this case the start cap is not doing its job its likely the switch is stuck in the running open position and just needs clean/lube from pasts user posts. Although the cap could be bad.

On my HF 2HP DC, the switch is clearly audible clicking about several seconds or so after the unit is shut off as it relaxes from the run position and closes again when the motor slows.
I don't recall if I can hear it click open when the motor starts but i can sure recall its clicking open at the end of use because all the other noise goes away.

[skamath]

thanks Loring.

i remember the click, but don't remember if it clicked the last time i shut it off. i will try and see if it is stuck open. i also have a multimeter and i guess could check if the cap is bad.

he said it hummed and made noises so it was getting power and it's not likely the power switch.
OTOH, as JR says they have been known to go bad so maybe a half-bad switch could lead to malfunction.
However, humming but not turning are usually symptoms of the centrifugal starter switch/capacitor system not working right.

The starter switch is set so its closed when the motors not turning. The capcitor is shaded on one winding to unbalance the phase and get the motor turning the right way. after it gets up to speed a weight pulls the switch open so that the starter capacitor is disengaged and not stealing current. In this case the start cap is not doing its job its likely the switch is stuck in the running open position and just needs clean/lube from pasts user posts. Although the cap could be bad.

On my HF 2HP DC, the switch is clearly audible clicking about several seconds or so after the unit is shut off as it relaxes from the run position and closes again when the motor slows.
I don't recall if I can hear it click open when the motor starts but i can sure recall its clicking open at the end of use because all the other noise goes away.

[LCHIEN]

thanks Loring.

i remember the click, but don't remember if it clicked the last time i shut it off. i will try and see if it is stuck open. i also have a multimeter and i guess could check if the cap is bad.

do you know how to check a capacitor with a multi meter?

[tseavoy]

Motor won't start

My drill press motor has the same problem. Whenever it won't start I bang on the motor with a piece of 2X4 and it starts. I guess the starting switch hangs up sometimes.

Tom on Marrowstone

PATIENCE, n. A minor form of despair, disguised as a virtue.
Ambrose Bierce

[skamath]

i have a multimeter which has that function. i'll check tonight.

do you know how to check a capacitor with a multi meter?

[milanuk]

Be sure to disconnect one leg of the capacitor so you don't get erroneous readings through unexpected parallel loops. And make sure you discharge that cap before you go touching the terminals - if you don't, it just may make a believer out of ya

[skamath]

so i tried to test the capacitor after i removed it from the motor. made sure it discharged first using the screwdriver technique. did it outside just to be safe. (there is saw dust all over my shop right now.)

the fluke multimeter registers 0L (autoranging mode) in the capacitance measurement mode. 0L i think means beyond range, so i am not sure what that means.

in the ohmmeter mode, it registers increasing resistance (starts at around 400 kohms.) does this mean that the capacitor is alive?

also, any instructions on the centrifugal switch thingie. where is it located? near the impeller side? how much of the motor do i need to open?

thanks in advance! i appreciate the help.


PS: for some reason having trouble locating a place where i can get the capacitor. there is a grainger store nearby where i work and i found a cap, but it was larger and i didn't know if it would fit under the the motor bump. anyways, i'll look some more. i don't know if it is part of the fun or not, but doing something the first time always takes so much time for me. (my little rant.)

[LCHIEN]

so i tried to test the capacitor after i removed it from the motor. made sure it discharged first using the screwdriver technique. did it outside just to be safe. (there is saw dust all over my shop right now.)

the fluke multimeter registers 0L (autoranging mode) in the capacitance measurement mode. 0L i think means beyond range, so i am not sure what that means.

in the ohmmeter mode, it registers increasing resistance (starts at around 400 kohms.) does this mean that the capacitor is alive?

also, any instructions on the centrifugal switch thingie. where is it located? near the impeller side? how much of the motor do i need to open?

thanks in advance! i appreciate the help.


PS: for some reason having trouble locating a place where i can get the capacitor. there is a grainger store nearby where i work and i found a cap, but it was larger and i didn't know if it would fit under the the motor bump. anyways, i'll look some more. i don't know if it is part of the fun or not, but doing something the first time always takes so much time for me. (my little rant.)

You don't say what Fluke meter you are using. the 80-series was and still is very popular. Older model 87s only go to 5 uF but newer ones go to 10,000 uF. I don't even know if you have an 87 or what. Starting caps can go several uF so OL might be correct. If the cap was not working, it would probably be zero and not OL.
Also in resistance mode the correct behavior is to start low and climb to OL with time. You can reverse the leads and start at low resistance again and go up. 400K would not be unreasonable for a low starting point.

So offhand I'd say your meter and your cap are probably OK given the limited info,

The centrifugal switch (mind you I've never taken mine apart) I think is located on the end of the shaft opposite end of the motor from the impellor. There may be a cover on that end of the shaft, part of the switch has to rotate with the shaft (to get the centrifugal action) and part of the switch will be fixed with the contacts.

When you find it some compressed air if its dusty or wd-40 and a little bit of working loose anything that's gummed up might work with out having to disassemble anything.

Good luck.

if you do have to replace the cap it should have some numbers on the side telling the voltage rating and capacitance value.

[skamath]

mine is 77IV i think and it measures to 9999uF. sorry forgot to mention that.

on the motor, there is a cover held by bolts. i didn't want to open it until i knew i had to.

the cap is 400uF, so given it is within the multimeter's range, shouldn't it have measured the right value?

You don't say what Fluke meter you are using. the 80-series was and still is very popular. Older model 87s only go to 5 uF but newer ones go to 10,000 uF. I don't even know if you have an 87 or what. Starting caps can go several uF so OL might be correct. If the cap was not working, it would probably be zero and not OL.
Also in resistance mode the correct behavior is to start low and climb to OL with time. You can reverse the leads and start at low resistance again and go up. 400K would not be unreasonable for a low starting point.

So offhand I'd say your meter and your cap are probably OK given the limited info,

The centrifugal switch (mind you I've never taken mine apart) I think is located on the end of the shaft opposite end of the motor from the impellor. There may be a cover on that end of the shaft, part of the switch has to rotate with the shaft (to get the centrifugal action) and part of the switch will be fixed with the contacts.

When you find it some compressed air if its dusty or wd-40 and a little bit of working loose anything that's gummed up might work with out having to disassemble anything.

Good luck.

if you do have to replace the cap it should have some numbers on the side telling the voltage rating and capacitance value.