15" Wide Belt Sander won't turn off

[Steve Jenkins]

I’m no help on this but want to say how impressed I am with the detail of the help you’re getting. People are spending a lot of their time diagnosing the problems. I’m not surprised.

[Josh Falcon]

I’m no help on this but want to say how impressed I am with the detail of the help you’re getting. People are spending a lot of their time diagnosing the problems. I’m not surprised.

Absolutely agree, very grateful for everyone that’s replied so far. I’m learning a lot as well, I’d be lost without the help I’ve gotten so far.

[Dave Sabo]

Originally Posted by Erik Loza
Josh, FYI that you appear to be missing a V-belt. Maybe you caught that already. Or does the upper pulley only take one? Every WB I have experience with has two, if not three belts. Looking good, by the way.

Erik



Yeah, I have a replacement I just havent gotten around to putting it on. I hadn't planned to run it under load until I got all the electrical stuff sorted. I'm actually wondering if it broke at some point and thats what decapitated the brake air line.

Hope you ordered two belts, the one in the pic looks a bit tired. Even if not, it's better to change out multiple belts in sets.

[Josh Falcon]

Hope you ordered two belts, the one in the pic looks a bit tired. Even if not, it's better to change out multiple belts in sets.

It was a matched pair, yes.

Fuses arrived so I went out and made some progress. Here's what I did.

1) Replaced fuses, E-stops tripped, turned on power. Waited ~10 min, measured 112V between 110/0V
2) Turned power off, disconnected Red 9 and Red 11 from M1/M2
3) Power on
4) Cleared E-stop on back of machine, measured 112V between 110/0V
5) Cleared E-stop on front control panel, M3 contactor released, measured 112V between 110/0V
6) Pressed Start 1 (sanding head), green light lit up while pressed, fuses checked out OK, measured 112V between 110/0V
7) Pressed Start 2 (conveyor), green light lit up while pressed, fuses checked out OK, measured 112V between 110/0V
8) Power off, reconnected Red 9
9) Power on, pressed Start 1 (sanding head), F1 blew. Amp meter jumped to about 5 amps for a split second
10) Power off, replaced fuse, reconnected Red 11
10) Power on, pressed Start 2 (conveyor), Conveyor operates! Pressed stop and start a few more times and the conveyor turns on and off as it should

I took a quick look to see if I could see if anything looked like it could be shorting out in the control panel or the enclosure but nothing jumped out. Could the M1 Contactor be the issue? I look forward to any and all hypothesis.

Thanks again everyone!

[Bill Dufour]

Disconnect the power out wires on the overload for the sanding head and try to turn it on and see if the contactor will stay closed with 240 volts at the output terminals. While they are both disconnected check the resistance from each of those wires to ground and to each other.
I guess since the motor ran before it is okay. maybe the contactor or overload has a internal short between poles or a short to ground.

[Stan Coryell]

The close coil for M1 appears to be shorted closed.

Check one thing before we proceed.
1. Lift the yellow wire (A1) from N.O. 13, leaving red 9
2. Measure voltage between the load side of the overload relay(yellow wire which ends up at A2) to red 9, while pressing the M1 start button. You should have 120 volts. If not stop and check back.

Those two yellow wires on M1 should go to, if I remember correctly, A1 and A2. A1 and A2 are the control power for the close coil. A1 should land on N.O. 13 along with red 9. A2 should be the load side of the O.L. relay. This is not what the single line shows. Yours looks right, but it's hard to tell from the pictures. Lift the wires off of A1 and A2. you should be able to read resistance between A1 and A2. Maybe 10 ohms? I'm not really sure. Yours will read 0 ohms, hence it is shorted closed. I can't say I've ever had a coil do that. They usually short open.

On NEMA motor starters coils are easily swapped, 2 screws and 2 wires. I can't say for IEC.

Your M1 isn't just a contactor, it's a motor starter. It has overload protection and auxiliary contacts. The only thing bad is the close coil, you may be able to replace just that. CN-25 is the size. With that and the manufacturer, you may be able to source a replacement coil. However, if it were me, I'd change it to something I could get locally. I use Colonial up here, they cary Square-D/ Schneider. I'd be happy to call and get a quote for you.

[Stan Coryell]

Re:
"I am surprised the panic bar switch is "normally open" In my experience stop switches should be normally closed for safety sakes. the way that is wired if the wires go bad the switch has no way to turn off the power."

We don't know how the limit switch is being used. It looks like a plunger type. Remember, N.O. / N.C. refers to the switch in your hand. In "clear" the N.O. contacts may be closed.
Or, there maybe a relay hidden somewhere. When the switch makes it puts power to the relay, opening 3 and 5 and putting power to the air brake. All speculation with out a proper single line.

[Stan Coryell]

Silly question.
Is the pneumatic brake disengaged, prior to pushing M1 start? Not that it has anything to do with F1 blowing, just curious.

[Josh Falcon]

Silly question.
Is the pneumatic brake disengaged, prior to pushing M1 start? Not that it has anything to do with F1 blowing, just curious.

Yes. The break engages when any of the E-stops are tripped and disengages when theyre cleared.

I'll run through procedures outlined above this evening and report back.

However, if it were me, I'd change it to something I could get locally. I use Colonial up here, they cary Square-D/ Schneider. I'd be happy to call and get a quote for you.

I appreciate the offer Stan. I was able to find an exact match for the M1 contactor online fairly easily. The brand is Taian, looks to be a lot of them out there. I figured it wouldn't hurt to have complete new unit just in case. I don't have a lot of $$ into this thing presently and I was anticipating having to replace something anyway. If this is all it needs I'll still be making out real well.

[Josh Falcon]

Hey all, sorry for the radio silence last few days, nothing new to report. Hoping to get an extra set of hands tomorrow to check the M1 contractor one last time per Stan’s most recent message, will report back on that tomorrow. The new contractor should be here Thursday so hopefully will have some good news by end of the week.

Thanks again for everyone sticking with me.

[Josh Falcon]

Check one thing before we proceed.
1. Lift the yellow wire (A1) from N.O. 13, leaving red 9
2. Measure voltage between the load side of the overload relay(yellow wire which ends up at A2) to red 9, while pressing the M1 start button. You should have 120 volts. If not stop and check back.

New contactor showed up today. Before I dig in and replace I wanted to address this real quick. I measured between Red 9 and what I think is A2 and I got 9V (with the A1 yellow removed) . When the M1 start button was pushed I got 113V, so sounds like everything checks out there? I took some detail photos of the M1 contactor for my reference, added below just in case. I circled in blue where I took my readings mentioned above.

My plan is to pull the contactor out this evening and see where we land. Wish me luck!


M1 detail 1 by Josh Falcon, on Flickr

M1 detail by Josh Falcon, on Flickr


overload detail by Josh Falcon, on Flickr

[Josh Falcon]

Well, I pulled the old contactor, wired up the new one, flipped the breaker and were back in business!! Motor fired up, conveyor runs, all the stops work, brake engages, everything checks out. I'm super excited to have this thing running. Few things to finish up, belts, piping some dust collection, getting it on the mobile base but I couldn't help but run a few pieces through this evening and its working great.

Big thanks to everyone who helped out along the way and stuck with me through all this. Huge thank you to Stan for all the detailed responses! This thing would still just be taking up space otherwise.

Josh

[Ron Selzer]

Well, I pulled the old contactor, wired up the new one, flipped the breaker and were back in business!! Motor fired up, conveyor runs, all the stops work, brake engages, everything checks out. I'm super excited to have this thing running. Few things to finish up, belts, piping some dust collection, getting it on the mobile base but I couldn't help but run a few pieces through this evening and its working great.

Big thanks to everyone who helped out along the way and stuck with me through all this. Huge thank you to Stan for all the detailed responses! This thing would still just be taking up space otherwise.

Josh

Glad it finally came together for you
Ron

[Stan Coryell]

I'm glad your machine is back up. It was a fun exercise. That's the first time I have heard of a coil shorting closed.

In the future:
This control circuit is 120 volts AC.
120 and 0 (the 0 is "common or neutral). NEMA transformers would be labeled X1 and X0, as I mentioned earlier.

A quick lesson in volts.

Voltage is a measurement between potential. Your home lighting and receptacles use the same power as our control transformer produces, or a "hot" and a "neutral". If your home has a metal water service, you should be able to measure "potential" or voltage between the "hot" and a water pipe even though the water pipe isn't part of the circuit.
The reason I mention this is because some control transformers don't produce a neutral. They are marked X1 and X2 (if they do use X2 as a neutral, X2 will be grounded to the equipment chassis). They simply step voltage down, say 60 volts on each "leg". This scheme wouldn't change our troubleshooting steps, but it would change our voltage readings.

One more thing to remember, voltage flows through a conductor. For example, a coil or pilot light may become conductors looking for potential. If I'm not sure of a scheme, I'll lift wires as Josh did, to eliminate the chance of back feed through an unknown component.

I can't stress enough to not make assumptions. Start where power comes in and work through the scheme. If the scheme isn't working correctly do NOT push contactors closed or "jump" things out. DO NOT under ANY circumstances apply unfused power or power from another source. Unless you have NO doubt what the failure is, like, bet your life on it. Just keep working through it with your meter. Bad things happened when you think you are smarter than the equipment. Trust me.

Stan

[Earl McLain]

This has been an awesome thread to follow. Speaks of many good things about this community. Glad to see a positive outcome in the end!! Josh's persistence left many of us with a great education. Thanks to all!!
earl