Bandsaw won't start - Electrical issue

[Neil Bosdet]

I have a Laguna LT18 Bandsaw that's about 5 years old. It has low
hours on it from hobby use only. I've never had any problems with it
before this morning. I was cutting a couple of boards last night and
used the brake/shut off pedal to turn it off as I have many times
before. I went to make a cut this morning and it won't power up. The
magnetic switch and stop button seem to be functioning properly albeit
without the motor actually turning on. I checked the brake shut off
switch and when I disconnected it the magnetic power switch didn't lock
in anymore. This indicates that it is working fine. I've checked all
the connections I can see and everything seems as it should. I can't
find a reset button on the motor or the switch so I don't think there
is one. Any ideas?
Neil

[Jesse Cloud]

I don't know this particular machine, but the symptoms sound like a failed capacitor. Look at the engine, see if there's a cylindrical bump on the side. Look for leaking fluid from the bump and smell for an off taste odor.
If that's the problem, you are lucky. The capacitor is a low cost item. Take the old one off (noting electrical connections) and call Laguna or a local small motor shop for a replacement part.

I have a Laguna LT18 Bandsaw that's about 5 years old. It has low
hours on it from hobby use only. I've never had any problems with it
before this morning. I was cutting a couple of boards last night and
used the brake/shut off pedal to turn it off as I have many times
before. I went to make a cut this morning and it won't power up. The
magnetic switch and stop button seem to be functioning properly albeit
without the motor actually turning on. I checked the brake shut off
switch and when I disconnected it the magnetic power switch didn't lock
in anymore. This indicates that it is working fine. I've checked all
the connections I can see and everything seems as it should. I can't
find a reset button on the motor or the switch so I don't think there
is one. Any ideas?
Neil

[Tyler Howell]

Elementry... Power to the machine?
Do the activated swithches supply power to the motor? You can check this with a meter.
Check it out and if it does we'll talk about motor T.S.;)

[Robert MacKinnon]

There is usually a motor overload relay inside the mag switch and it is possible that this overload realy has tripped. If you look inside the mag switch, look for a trip indicator and reset button. If tripped, just push in the button to reset the overload relay.

[Bill Boehme]

Does the stop switch need to be rotated to unlock it as the one on the MiniMax does? Are the upper and lower doors closed? Has the microswitch on the brake pedal moved?

Bill

[Don Baer]

Neil,
I'm going to assume that your saw is a 220 Volt circuit. Usuual the control circuit is 110 Volt using the neutral and one of the legs of the 220. By virture of gthe fact that you mag starter pulls in you have already rulled out all of the interlocks etc. It sounds like either you not getting power through the starter. Of the overloads are tripped that usual mean the the starter won't pull in so you can rule that out also. With a volt meter and the starter pulled in check the voltage on the out put of the starter. if you have voltage there. If you don't then check the voltage at the input side of the starter. It's possible that one side of the 220 is open, check your breaker supplying it.

[Neil Bosdet]

The capacitor looks fine. It doesn't seem likely that this is the problem.

[Neil Bosdet]

Tyler,

There is power to the machine. I have a multimeter and can remove the cover to the magnetic switch to expose the many wires that terminate here. However, I don't know how to go about testing this. Suggestions?

[Neil Bosdet]

Robert,

I have removed the cover to the switch but I don't see a trip button or something like that. Is it possible that it could be on the back?

[chris del]

Even know this saw is equiped with a magnetic starter, the motor may have its own manual overload switch..... I know this sounds elementary, but I personally have overlooked a simple thing like this and it cost me $$$$.

[Neil Bosdet]

Hi Bill,

My machine sounds like it has a similar set up as yours. All the things you mention seem to be in order.

Don,

I'm not sure what you're saying exactly. Could you retype??? The breaker is fine. Power is getting to the unit.

[Neil Bosdet]

OK. Here is a link that shows my power switch. It's not actually magnetic (my error). There is a stop button wired to this switch as well. I really don't feel it's the motor. It's got to be something electrical.

http://www.klocknermoeller.com/pkz/pkzm0-20.htm

I pulled off the stop button and test the connection points and get nothing on my meter but I don't know if I've got my meter on the correct settings to test this. I'm hoping someone can look at the switch above and tell what to test.

Thanks,

Neil

[Don Baer]

Neil,
The one you are showing is for a 3 phase motor, I'll assume that your on Singal Phase. There should be wire going into L1 and L2 or L3 Check that you have 220 volts there, then with the contactor energised, check that you have voltage on T1 and T2 or T3 which ever have wires going to the motor.

[Neil Bosdet]

I have wires coming into L1, L2 and L3. Same with the "T" terminals. Which ones do I test?

[Don Baer]

The may be using one set of contact as the holing circuit for your mag starter. The one that come from the power feeding the starter are the ones that will be carrying the current to the motor. If the plug is attaced to L1 and L2 then then T1 and T2 would be feeding the motor. That what you test.

[Bartee Lamar]

Make sure the push button stop switch is pulled all the way out.

At least that is what happened to me on a new HD16.

[Neil Bosdet]

I have power at L2 and L3. If I turn the unit on and test the T terminals, I have no power at them with any combination.

[Robert MacKinnon]

OK. Here is a link that shows my power switch. It's not actually magnetic (my error). There is a stop button wired to this switch as well. I really don't feel it's the motor. It's got to be something electrical.
Actually,that switch is a magnetic switch. According to the data sheets (http://www.moellercatalog.com/Documents/Chapter_8/08006_17.pdf and http://www.moellercatalog.com/Documents/Chapter_8/08060_63.pdf): (http://www.moellercatalog.com/Documents/Chapter_8/08060_63.pdf%29:)


The PKZM 0-... is a 3-phase thermal magnetic motor protective
device incorporating adjustable bimetal trips for motor overload
protection and magnetic trips to de-energize the motor
circuit in case of a short-circuit.
It may be possible that either the internal mag short circuit trip or thermal trip is triggered and you need to reset. From the photo in the URL that you referenced, the yellow dial sets the thermal cutout value (FLA of your motor) and there appears to be a test switch. I could not see whether there is a reset switch from the picture and there is no suggested wiring diagram from the technical documentation I was able to find. In addition, there appears to be a small window just above the T3 terminal which suggests a trip indicator. Is this window clear or yellow on your mag starter?

The data sheet said explicitly that all three legs must be connected, even for single phase operation, which accounts for L1, L2 and L3 being connected. It is possible that T2 connects to L3 through a jumper (have you checked?). Also, where is the aux. stop switches wired into the circuit -- I was unable to see coil or auxillary connections from the data sheet photo.

This is the internal wiring of the PKZM0-20 from the data sheet:
http://img100.imageshack.us/img100/7083/clipboard01cp1.jpg
This diagram shows the main contacts, followed by the bimetal thermal trip followed by the short circuit protection. Assuming you are running this machine off of 230V 60Hz single phase
(1) and if you have measured voltage between L1 and L2 (or L3) at 230V
(2) and if you have rotated the switch to the I position
(3) and you have measured 0V volts between T1 and T3
Then either the main contacts in the mag starter are defective or one of the internal trips are triggered and you have to reset them.

A long shot may be a problem with the Aux. stop circuit however I doubt very much that this circuit is acting up. To make sure that one of the aux. stop switches are not giving trouble, test continuity of the circuit. There should be continuity (0 ohms) between both leads of the aux. stop switch circuit. If it reads open circuit (infinite ohms), then one of the stop switches is stuck in the engaged position and your trouble shooting efforts should be directed there.

It seems reasonable to me that the motor is OK.

[Don Baer]

I have power at L2 and L3. If I turn the unit on and test the T terminals, I have no power at them with any combination.

Neil,
Is the contactor energised when you test T2, T3 ? If not then try it with it energised.

[Neil Bosdet]

Wow Robert. Thanks for the detailed response. And thanks to everyone else for their suggestions.

Robert, Your assumptions are correct. Single phase etc and have checked the stop switches. I get a voltage reading testing L2 and L3. If they were engaged I would not be able to turn the mag switch on and have it stick. So I don't think that's the issue. My switch looks almost identical to the picture (link) I posted. There is a hole that says "test". ??? A trip indicator??? I don't know. It doesn't look like anything. If I do need to reset the mag switch, how do I do it?

Neil

[Robert MacKinnon]

Neil,

That's a question for which I don't have an answer. I can't find enough information about your motor control to give a qualified answer. I've been trying to find similar units made by other manufacturers who may have posted more detailed information than K-M that can lead me in the right direction.

I could hazzard a guess that the test switch is also the reset switch under trip conditions on your motor control (assuming that controller is a manual reset device). You might try using a small screwdriver to push the test button.

However, if the reset is automatic, then the unit will reset after a short time by itself.

Since you've pretty much isolated your problem, it is probably prudent for you to contact the manufacturer to solve this. They will have the technical expertise on hand to answer your questions.

[Neil Bosdet]

It always seems these things happen on weekends. This problem presented itself on Saturday morning. I have full intention to call Laguna tomorrow morning. I was hoping to solve it before then. I will try the test button again. I poked in their with a screwdriver and nothing seemed to happen (there didn't seem to be a button). It's been over a day and it hasn't reset itself so I don't think that will happen.

If you have anymore ideas please let me know.

Thanks a bunch,

Neil

[Bill Boehme]

You can't tell if a capacitor is bad or good by looking at it (BTW, for everyone's information -- if there is a capacitor then it is a single-phase motor -- three phase motors do not use capacitors). To test the capacitor, lift one lead and use the ohmmeter scale on your multimeter to measure resistance -- you should get something greater than 1 Megohm. However, it can read infinity (open circuit) and still be bad. Typically, on a single phase motor with a bad capacitor, the symptom will be that the motor hums and either just barely moves or does not move at all. From what you have said, however, it appears that power is not getting to the motor. You could temporarily bypass the starter to check the motor if you are confident in your ability to do electrical troubleshooting.

Bill

[Neil Bosdet]

Laguna tech support believes my switch contact has packed it in. I'll have to buy a new one to find out. Ouch.

Thanks for all your help.

Neil

[Kirk Poore]

Laguna tech support believes my switch contact has packed it in. I'll have to buy a new one to find out. Ouch.

Thanks for all your help.

Neil

Neil:

Many of these are modular. If yours is, maybe you can pick up just the part you need. If not, look on ebay. A NEMA size 1 manual starter shouldn't be too bad there (I bought one for about $40 a couple of years ago without waiting too long or looking too hard). Even in the likely event you have to get heaters sized just for your motor, you still should be way ahead. And it will probably be a better starter than the one you've got now, so it will last as long as your saw.

Kirk

[Robert MacKinnon]

Neil,

Too bad about your starter. You could shop around online and find an equivalent unit either from K-M or from another manufacturer like ABB, Siemens or similar. You'd have to research whether another manufacturer's starter works with your front panel buttons. I was looking at RS Components' web site ( http://rswww.com/ ) and they sell these starters for around £24-34, not too bad actually.

Kirk, The starter is an IEC sized unit, not NEMA so retrofitting a NEMA 1 starter into Neil's bandsaw would require some rewiring and mechanically relocating elements. Not fun.