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Bandsaw wont turn on

3K views 18 replies 7 participants last post by  Tennessee 
#1 · (Edited by Moderator)
hi there,

Just bought a bandsaw on craigslist. It was working fine but I would notice that the light which is on the same breaker would dim a bit when I would turn on the bandsaw. But the saw was still working when I would use it the first 2 weeks. Recently, I turn on the bandsaw and it ran for maybe one second then shut off. Since then, it has not turned on at all even switching outlets. the breaker is still on and other tools still work in the outlet. Is the bandsaw shot or is there a fix for this? The manual wasn't any help. Thanks!

PS I am a newbie.

Chris
 
#2 · (Edited by Moderator)
The saw is far from being "shot". Sounds like a simple motor problem, but without more specifics, kind of hard to say what that might be. Sounds generally like the start circuit in the motor… how comfortable are you at cracking open a motor and checking the centrifugal switch and capacitor?

Could be as simple as sawdust stuck in the switch. Worst case scenario is replacing the motor.

Cheers,
Brad

PS: The make/model of saw and maybe a couple pictures of the motor would be helpful as well.
 
#4 ·
I am not sure I would know what I was looking at in terms of the motor so that might be out of the question. But I guess I can give it a shot. I will also test at a different location altogether to see if it turns on at a different circuit. I am travelling for work now but will test it out when I get home. Thanks for your quick replies!

fingers crossed
 
#5 ·
Well I tried the bandsaw on a different circuit and it didnt turn on. See the pictures for the model, motor, and electrical goings on. Let me know if there is something that can be done. I have tried to blow off as much saw dust as I could.





 
#6 ·
You could have fried any one of those diodes or a solder connection may have failed on that board. Can you bypass the switch and circuit board and apply power directly to the motor to see if that's still good? I had a Black and Decker like that and it was variable speed but just had a rheostat of some kind. If you can't trouble shoot that board and the motor is still good I'd get a router speed controller from Harbor Freight and use that to adjust speed.
 
#7 ·
Well… ignore what I said about opening up the motor and centrifugal switch stuff! That is a variable speed saw with a brush type motor,. First thing I'd do would be to check the brushes on the motor. Manual should tell you how to go about that. I'd also grab a meter and check to make sure voltage is getting to the switch and speed control board, and make sure all the wires/connections are well seated. Could just be a loose wire/connector somewhere. If it's the speed control board, you might be SOL and have to find an alternative way to control the speed.

Cheers,
Brad
 
#8 ·
Those boards generally fry open and don't work at all, or they work.
Since the light was dimming for a while when you started noticing the problem, I'd take a chance at possibly a bad set of brushes first.

If not, then Brad is probably right, the board is fried and all I can say is welcome to the wonderful world of Sears Direct Parts Depot.com.
 
#10 ·
Apologies dhazelton - wasn't trying to run over you. I had a Sears saw given to me that had a very similar board. Found out from other forums that on a lot of these by Sears, you cannot just bypass the board. Somehow they wire in an electronic start circuit, or change the voltage within the board to make it essentially impossible to eliminate the board. Not sure how it all works, but found out that the motor can still be good but not run without that board.
 
#12 · (Edited by Moderator)
That is weird, and pretty douchy of a manufacturer to do that. One would think that if you bought a tool and it failed you might go to another manufacturer to replace it because yours was not repairablel. I guess the nimrods in management don't get human behavior.

Chris - take the circuit board if you can and look at the back it for any cracks in the solder with a magnifying glass. A touch of a hot soldering pen is usually enough to fix a break. I fixed a TV horizontal circuit by doing that. It's worth a shot. It might be from the saw vibration. With a TV it was hot/cold cycles. You can do it if I did it.
 
#13 ·
The one I got was a Sears variable speed scroll saw, but it looked a LOT like that board, including a number of little surface pots on the board, (like VR2,3 and 4 on the board above), obviously meant to set up parameters on how the board will control the motor.

dhazelton is right about trying to find a break. It is as good a shot as any. Maybe a connection fried or broke before a component died.

But short of that, it may be that the motor was overloaded at some point and overheated one of the SCR units on the board, or even a diode circuit.

Or…when the saw was dimming the lights, it was taking in more amperage than usual to try and get the motor up to speed. It finally hit a wall, and something in that board probably opened up. The problem might have originally been in the motor, (friction drag, bad brushes, dirty armature), but in the end, my guess is the control board died trying to make the motor run.

I've always wondered why these saws existed. Why do you need an infinite speed bandsaw, when the bulk of the market is one or two speed? I can understand on a scroll saw. Bandsaw, not so much.
 
#16 ·
man I thought I was getting into woodworking, not electrical repair! I was listening to a WoodTalk about some people make it a secondary hobby to repair old tools that are meant to repair / build wood projects. Takes all kinds.

I think at this point I am going to try to deconstruct the board a bit to see if I can see anything overt on the back end. Problem is I dont have a soldering tool at all. Wonder if any friendly neighbors might be able to help me out.

Orrrrr….if one of you just want to send me a brand new band saw, that would be much appreciated as well!!

Thanks for your input everyone!
 
#17 ·
Update!

I took out the circuit board. Didn't see any issues on the back. The power was coming into the board which I discovered by using a voltage detector. Then I said lets see what happens if I just connect the black wires from the power input to the line directly to the motor. When I did that, spark, smoke and smell. Around the motor. Not sure if I just fried the whole thing but the two black wires were singed or fused together. Looks like it's time for a new band saw. But I am going to keep this one to try to educate myself on motors.

If you think it is still salvageable let me know. Or if you just want to make fun of my lack of electrical skills and common sense, that is welcome too.

Chris
 
#19 ·
I think dhazelton has it right on the mark. The SCR's on the board would be supplying DC current to the motor. Sending AC to a DC motor does exactly what you saw.

I still don't know why Sears would go to all the trouble to use a DC motor with an elaborate board control with a saw at that price point, when a simple universal motor with a rather simple HF style control would do essentially the same thing. I guess they wanted the amperage/torque to stay up at slow speeds.

Just another reason why I'm not a Sears fan.
 
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