# Import Lathe Contactor Questions 12x37



## StephenZ (Oct 4, 2018)

Hi everyone, Stephen here, new to the site. I've been searching through forums and found a few similar topics, but not the exact answers I was looking for. Here goes...I'm mechanically inclined, but not a professional electrician, so bear with me... 
I picked up a barely used harbor freight 12x37 gap bed metal lathe last week. Ran it while i was there, the owner was really helpful and knowledgable...(meaning, I don't think anything was suspect). Anyway, once I got it home and mounted on a stand, I ran it a couple times while figuring out all the levers and whatnot. (I'm stepping up from a small 7x12 lathe, btw) I'm not sure if I switched something out of order, or something, but it suddenly didn't want to run anymore. Here are the symptoms:
-Power light comes on when switch is turned.
-Spindle doesn't respond to F or R lever, but I hear one of the contactors click.
-I found that the Fwd and Rev contactors will work if I manually press the mag plunger.
-The clicking when using the direction lever is the first contactor...whatever that one is called...not a direction one. when I switch to fwd or rev, it releases its magnetic hold and nothing happens. If I leave the lever engaged and manually press the contactor, the spindle will go perfectly. 
So, I guess I'm asking for advice on what my likely culprits are. 
The CN-11 contactor? 
Did it just happen to give up its mag hold? 
The motor jumps to life quickly when I push the contactor, so would that make the motor fine?
Direction switches? They seem ok, pretty basic switches..
The thermal protector? 
Sorry for the essay...Thanks for any advice.
-Stephen


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## TonyM (Oct 5, 2018)

Don't know what that specific machine has in the way of safety switches. If there are any check they are engaged maybe on chuck guard or drive guard.


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## RM-MN (Oct 5, 2018)

I found a manual for that lathe or similar.  The problem might be a safety interlock or you may need a new contactor (relay).  

https://manualzz.com/doc/3201707/harbor-freight-tools-43681-user-s-manual


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## StephenZ (Oct 5, 2018)

Thanks for the responses, guys. So, there aren't any safety switches that I could find...or find in the manual/online anywhere. Damn. Strangely, before work this morning, I fiddled around with it some more and it randomly started working in reverse only. I switched the reverse and forward trigger wires coming from the main relay/contactor and it worked in forward. Tonight, it didn't want to work again....then it did a little bit...so I switched wires back again, to test it and it stopped working at all...that's where I'm at now.. The main contactor/relay seems to start buzzing while I'm switching the direction lever back and forth...I just ordered a new CU-11 contactor to replace this one...I hate throwing parts at it, but I'm not sure what else to do...since it worked randomly a couple times, it seems like maybe an electrical component is losing the big fight...the main relay seems likely? Thanks again, everyone.
-Stephen Z

Edit: I read somewhere that the CU-11 is a replacement for the CN-11...they look to be the same (minus the auxillary contactor on the CU in my pic...) specs the same, too.. Thoughts?


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## Wizard69 (Oct 6, 2018)

StephenZ said:


> Thanks for the responses, guys. So, there aren't any safety switches that I could find...or find in the manual/online anywhere. Damn. Strangely, before work this morning, I fiddled around with it some more and it randomly started working in reverse only. I switched the reverse and forward trigger wires coming from the main relay/contactor and it worked in forward. Tonight, it didn't want to work again....then it did a little bit...so I switched wires back again, to test it and it stopped working at all...that's where I'm at now.. The main contactor/relay seems to start buzzing while I'm switching the direction lever back and forth...I just ordered a new CU-11 contactor to replace this one...I hate throwing parts at it, but I'm not sure what else to do...since it worked randomly a couple times, it seems like maybe an electrical component is losing the big fight...the main relay seems likely? Thanks again, everyone.
> -Stephen Z
> 
> Edit: I read somewhere that the CU-11 is a replacement for the CN-11...they look to be the same (minus the auxillary contactor on the CU in my pic...) specs the same, too.. Thoughts?


It kinda sounds like there is an external switch causing you issues. possibly an over travel to the saddle?    Unless you have a accurate electrical diagram you are basically shooting in the dark.    It is very difficult to do diagnostic work over the net plus I don't want you to end up dead.    To that end you might want to try finding somebody locally with a bit of an electrical background.

By the way, during machine tool moves there is a very high probability of something getting damaged electrically.    As always a close visual inspection is the first order of business.


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## StephenZ (Oct 6, 2018)

Wizard69 said:


> It kinda sounds like there is an external switch causing you issues. possibly an over travel to the saddle?    Unless you have a accurate electrical diagram you are basically shooting in the dark.    It is very difficult to do diagnostic work over the net plus I don't want you to end up dead.    To that end you might want to try finding somebody locally with a bit of an electrical background.
> 
> By the way, during machine tool moves there is a very high probability of something getting damaged electrically.    As always a close visual inspection is the first order of business.




I have general diagrams of the machine and other similar ones. I can't find any indication of safety switches or anything that would de-energize the contactor when the spindle direction is selected...but, yes, I would not be surprised if there was some kind of damage during transport. I had to use my trailer to haul it 15 miles or so...CA roads...not good. 
I also appreciate you not wanting me to end up dead.... I'd like to keep going for a bit longer, too... I'm a general contractor and have wired many homes, and restored several cars, I just haven't worked with lathe wiring and the use of multiple contactors, etc... I'm not saying I'm a pro, by any means, (I actually can't stand doing electrical) but I've been bitten a few times in my youth and will definitely be very careful..


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## Anatol (Oct 6, 2018)

Coincidentally, I just posted a wiring diagram on this thread
https://www.homemodelenginemachinis...-12x36-lathe-wireing.22761/page-2#post-314705
Its an older model but similar (?) Hope its helpful.
If you can't find a correct and readable circuit diagram, you just have to make your own, can't really proceed without it. Tedious but useful long term.  As often and not its a bad connection. Check continuity. Any sign of corrosion? I'd check any remote switches, as suggested. If you find corrosion at contacts, cut wires and reconnect. For hard to get to contacts (ie in contactor) theres an expensive but magical contact cleaner called deoxit. 
BTW, a contactor is electromagnetic (a big relay), no permanent magnet, afaik.


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## StephenZ (Oct 7, 2018)

Anatol said:


> Coincidentally, I just posted a wiring diagram on this thread
> https://www.homemodelenginemachinis...-12x36-lathe-wireing.22761/page-2#post-314705
> Its an older model but similar (?) Hope its helpful.
> If you can't find a correct and readable circuit diagram, you just have to make your own, can't really proceed without it. Tedious but useful long term.  As often and not its a bad connection. Check continuity. Any sign of corrosion? I'd check any remote switches, as suggested. If you find corrosion at contacts, cut wires and reconnect. For hard to get to contacts (ie in contactor) theres an expensive but magical contact cleaner called deoxit.
> BTW, a contactor is electromagnetic (a big relay), no permanent magnet, afaik.




Yes! thank you. I saw your post there, too. I had asked advice on that thread, too, since it was so similar to my issues and was on the same lathe. I think the fact that the diagram is older, is actually perfect. My machine is probably 10-12 years old, so the tech seems to match it. Thank you!


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## Brian Lawson (Oct 7, 2018)

StephenZ said:


> Hi everyone, Stephen here, new to the site. I've been searching through forums and found a few similar topics, but not the exact answers I was looking for. Here goes...I'm mechanically inclined, but not a professional electrician, so bear with me...
> I picked up a barely used harbor freight 12x37 gap bed metal lathe last week. Ran it while i was there, the owner was really helpful and knowledgable...(meaning, I don't think anything was suspect). Anyway, once I got it home and mounted on a stand, I ran it a couple times while figuring out all the levers and whatnot. (I'm stepping up from a small 7x12 lathe, btw) I'm not sure if I switched something out of order, or something, but it suddenly didn't want to run anymore. Here are the symptoms:
> -Power light comes on when switch is turned.
> -Spindle doesn't respond to F or R lever, but I hear one of the contactors click.
> ...


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## Brian Lawson (Oct 7, 2018)

One thing that has not been mentioned, in either this thread or in the other recent thread, has to do with any common FWD-REV contactors/relays is that they generally will have an NC (normally closed contact) in series with the "opposite direction" contactor.  That is, each has a "back contact" that stops the "other contactor" from pulling in if that contact is "open".  On larger equipment, there is normally also a mechanical interlock.
I see that someone has also mentioned a safety switch on the "change gear cover", and on larger lathes, there is a switch that stops motion if the foot brake is applied. 

It is difficult in the photos to "see" how the wiring is terminated at each connection.  If "stakon" crimp terminals were used, and they are NOT made by T&B, then they have a bad habit of cracking but then "laying" in place, so that they will have go/no-go state,  depending on who may have just sneezed!!  Very tough to diagnose and find.  Give EVERY wire a slight "tug" to see if they are still OK, and not either broken or loose.

Also note that the "drawing(s)" submitted show the lathe to be 220VAC single phase.  Some where on the drawings, there should be "overloads" provided, and on one I think I saw the term "heater", which is probably the overloads. 

Good luck.

Brian Lawson, Bothwell, Ontario.


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## StephenZ (Oct 7, 2018)

Brian Lawson said:


> One thing that has not been mentioned, in either this thread or in the other recent thread, has to do with any common FWD-REV contactors/relays is that they generally will have an NC (normally closed contact) in series with the "opposite direction" contactor.  That is, each has a "back contact" that stops the "other contactor" from pulling in if that contact is "open".  On larger equipment, there is normally also a mechanical interlock.
> I see that someone has also mentioned a safety switch on the "change gear cover", and on larger lathes, there is a switch that stops motion if the foot brake is applied.
> 
> It is difficult in the photos to "see" how the wiring is terminated at each connection.  If "stakon" crimp terminals were used, and they are NOT made by T&B, then they have a bad habit of cracking but then "laying" in place, so that they will have go/no-go state,  depending on who may have just sneezed!!  Very tough to diagnose and find.  Give EVERY wire a slight "tug" to see if they are still OK, and not either broken or loose.
> ...




Yes, all good bits of info. I wish there were some sort of safety switch that I just didn't see, but I've been over every inch of this thing and see nothing...kind of odd, really. Yeah, I hear you about those crimp on connectors. I have tugged on each one and checked their set screws, too. Always good practice! 
Yes, 220v single phase. It has a thermal overload that seems to be functioning properly. I traced the current through it in on and off positions and tested the breaker feature of it. It popped and reset fine. That should be good, right?


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## DJP (Oct 7, 2018)

Back up one more device and test the L1 and L2 fuses/breakers in your panel box. I have seen strange things happen when one side of the line voltage is missing or weak.


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## StephenZ (Oct 8, 2018)

DJP said:


> Back up one more device and test the L1 and L2 fuses/breakers in your panel box. I have seen strange things happen when one side of the line voltage is missing or weak.



Funny, you say that. I was standing next to the plug this morning and thought the same thing. Ran it back to the sub panel I had installed...all good.


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## Wizard69 (Oct 9, 2018)

StephenZ said:


> Funny, you say that. I was standing next to the plug this morning and thought the same thing. Ran it back to the sub panel I had installed...all good.



I tried looking at the photo you posted with respect to the relay you think is a problem.  The first problem to resolve is are you changing directions with the motor stopped?    The forward and revers should be electrically interlocked to prevent that and likely mechanically interlocked.  

As for the relay in question what do you mean by pops out?    Is the relay shutting off or does it have some sort of overload function.   (I can’t see from the picture what it really does in the circuit).  Normally when I hear the word pop, I think breaker or overload device that needs to be reset.   This may sound picky but it helps to understand what you have happening here.   At the moment I believe that the switching of motor direction is purposefully shutting off this relay.  

I could be wrong there but at this point to go further would require ringing out the electrical system.  

Also you mentioned single phase operation.   Frankly it has been so long I’ve forgotten how that is done with relays on a single phase system.   

Lastly there are a number of cables leaving that panel box, the must go someplace.


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## StephenZ (Oct 9, 2018)

Wizard69 said:


> I tried looking at the photo you posted with respect to the relay you think is a problem.  The first problem to resolve is are you changing directions with the motor stopped?    The forward and revers should be electrically interlocked to prevent that and likely mechanically interlocked.
> 
> As for the relay in question what do you mean by pops out?    Is the relay shutting off or does it have some sort of overload function.   (I can’t see from the picture what it really does in the circuit).  Normally when I hear the word pop, I think breaker or overload device that needs to be reset.   This may sound picky but it helps to understand what you have happening here.   At the moment I believe that the switching of motor direction is purposefully shutting off this relay.
> 
> ...



Ah, yes, sorry, poor choice of descriptives. The ‘pop’, I meant to describe the de-energizing of the magnetic contractor. When power is on to the machine, that first relay/contactor pulls in and should stay, I believe. When a spindle direction is chosen, that contactor de-energizes and nothing moves. I believe the contactor is going bad and can’t hold when the spindle direction is chosen. 
And, no, I never would try changing direction when the is motor moving.
I’ve also run down all the wires in the machine to their destinations and figured the purpose and currents of them. Definitely nothing going to any safety interlock anything. 
Short of something else I’ve missed, I’m fairly certain it has to do with something in the contactor/transformer area. Of course, I’m waiting for my new green power light/holy grail of electrical circuits before I can do anything else...lol.
Thank you for your help!


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## StephenZ (Oct 9, 2018)

Wizard69 said:


> I tried looking at the photo you posted with respect to the relay you think is a problem.  The first problem to resolve is are you changing directions with the motor stopped?    The forward and revers should be electrically interlocked to prevent that and likely mechanically interlocked.
> At the moment I believe that the switching of motor direction is purposefully shutting off this relay.
> 
> Interesting. Even if I’m switching properly, something in that direction switch-main relay/contactor-the direction contactors may be de-energizing that relay? The direction switches go through that first main relay/contactor, so would that further implicate that relay as the failure? That’s where the ‘buck’ seems to be stopping with all the wire tracing I’ve done..


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## DJP (Oct 9, 2018)

If you are convinced  that the relay is faulty bypass it with a suitable test lead and see if the machine runs as intended. You can build a test lead with a breaker in the line in case there is a short. I have one with a 10 amp breaker just for this testing process. Isolating the failed component is the objective. Replacing it with a known good part is the next step.


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## Cogsy (Oct 9, 2018)

I'm not much of an electrical guy (to put it mildly) but I just remembered back when I had an issue with one of the capacitors on my lathe motor. The first sign was the magnetic contactor 'playing up' and struggling to stay engaged. Sometimes it would, sometimes it wouldn't, then the cap blew and once I replaced it all was good. Not saying it's your issue, just mentioning it as I remembered it.


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## StephenZ (Oct 10, 2018)

Cogsy said:


> I'm not much of an electrical guy (to put it mildly) but I just remembered back when I had an issue with one of the capacitors on my lathe motor. The first sign was the magnetic contactor 'playing up' and struggling to stay engaged. Sometimes it would, sometimes it wouldn't, then the cap blew and once I replaced it all was good. Not saying it's your issue, just mentioning it as I remembered it.



Ah, the motor caps.. when that happened, were you still able to manually engage the contactor and run the motor? When my contactor de energizes, I can push it back in and hold it and the motor fires right up immediately.


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## ignator (Oct 10, 2018)

StephenZ said:


> Hi everyone, Stephen here, new to the site. I've been searching through forums and found a few similar topics, but not the exact answers I was looking for. Here goes...I'm mechanically inclined, but not a professional electrician, so bear with me...
> I picked up a barely used harbor freight 12x37 gap bed metal lathe last week. Ran it while i was there, the owner was really helpful and knowledgable...(meaning, I don't think anything was suspect). Anyway, once I got it home and mounted on a stand, I ran it a couple times while figuring out all the levers and whatnot. (I'm stepping up from a small 7x12 lathe, btw) I'm not sure if I switched something out of order, or something, but it suddenly didn't want to run anymore. Here are the symptoms:
> -Power light comes on when switch is turned.
> -Spindle doesn't respond to F or R lever, but I hear one of the contactors click.
> ...


I'm going to assume that the correct schematic is the one RM-MN posted a link to, as this was a direct HF. If you have an HF model number that should be included in your post.
I suspect it is the KA contact that has failed open. This is a safety inter lock to require the FWD-RVR selector to be in the off position. It latches up this interlock by applying power to the KA relay coil when the FWD-RVR selector is off.
Your bypassing all this when you manually engage the motor by closing the KM1 or KM2 motor contactors.
Your motor is not the issue if it starts up by manually pressing the KM1/KM2 magnetic switches.
You need a voltage ohm meter and with the power plug removed, check the KA contact that is pointed at in the below schematic. If the meter reading (in ohms mode) shows low ohms, when you manually close it, then check for loose wiring. If no issue found, then power the machine up and use the volt meter set to measure low AC volts, for the control transformer output. Note the one side that shows 0 (zero) that is a common, connect that one lead to your volt meter. The other lead connect to the KA magnetic coil terminal, and see if it shows voltage when you move the direction selector into FWD or RVR. If not, follow the wiring  to the source of why it's open.
In the below schematic, where I have "these KA contacts open...." is not supposed to happen when the direction is selected, your indicating this as a problem, that from my limited input, indicates the KA holding contact is not in the circuit from either it's failure of wiring problem. Note that when no direction is selected the SA1 and SA2 direction switches provide power to the KA coil. You indicate you hear this close.
The FR and it's switch contact appear to be OK, this is the motor overload. Everything would be off if the FR switch was open.
I don't know what the SA3 or SB1 is about, does your machine have a foot brake? Then one of these switches is to shut motor power off when used.
HL is your power on indicator light, you indicate it's on, so I think messing with this is the wrong path.

But if this is not the schematic to your machine, then all this becomes moot.


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## Cogsy (Oct 11, 2018)

StephenZ said:


> Ah, the motor caps.. when that happened, were you still able to manually engage the contactor and run the motor? When my contactor de energizes, I can push it back in and hold it and the motor fires right up immediately.


 Actually, I believe I confused myself and this was a different issue. The one I'm thinking of was a forward/reverse switch going bad and when I pushed and held the button in I would  often get the mag switch 'bouncing' in and out but not holding. The motor would start to spool up at this point. Sometimes it would engage, sometimes it wouldn't. As the switch failed over a couple of days it went from being a couple of clicks from the mag switch when trying to start to impossible to get running fairly quickly.


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## StephenZ (Oct 11, 2018)

Cogsy said:


> Actually, I believe I confused myself and this was a different issue. The one I'm thinking of was a forward/reverse switch going bad and when I pushed and held the button in I would  often get the mag switch 'bouncing' in and out but not holding. The motor would start to spool up at this point. Sometimes it would engage, sometimes it wouldn't. As the switch failed over a couple of days it went from being a couple of clicks from the mag switch when trying to start to impossible to get running fairly quickly.



Are you referring to the switches on the front next to the change box? I think I hooked up my meter to them and they were switching on and off..would anything else be wrong that wouldn't show with the multi meter?
I should have the new power light monday, and the new main relay/contactor is in place now...if it doesn't work, maybe I should just wire up a drum switch or something...lol. For such a small amount of wiring, it sure gives a hell of a pain, doesn't it??
Thank you for all the help, Cogsy! You're in Aus, huh? Odd question, do people still love Jamie Durie over there?


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## minh-thanh (Oct 11, 2018)

I think it looks like this :


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## Cogsy (Oct 12, 2018)

StephenZ said:


> Are you referring to the switches on the front next to the change box? I think I hooked up my meter to them and they were switching on and off..would anything else be wrong that wouldn't show with the multi meter?
> I should have the new power light monday, and the new main relay/contactor is in place now...if it doesn't work, maybe I should just wire up a drum switch or something...lol. For such a small amount of wiring, it sure gives a hell of a pain, doesn't it??
> Thank you for all the help, Cogsy! You're in Aus, huh? Odd question, do people still love Jamie Durie over there?



I think my lathe is different to yours, but yes, the switches on the front. Mine simply has an on button and separate off button, and a 2 way direction switch. The on button is a momentary switch that engages a magnetic switch (relay?) with a heavy 'thunk' noise. When the directional switch started to fail (literally began to fall apart internally) it was apparently not giving quite enough contact to maintain the circuit for the magnetic switch and it would throw out. Holding the 'on' button in would generate a succession of 'thunks' as the magnetic switch was trying to stay engaged but kept throwing out.

Jamie Durie...I have heard the name and I know he used to do something on TV but I'm not really familiar with him. Haven't heard the name for a while so maybe he's not so popular any more.


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## StephenZ (Oct 12, 2018)

Cogsy said:


> I think my lathe is different to yours, but yes, the switches on the front. Mine simply has an on button and separate off button, and a 2 way direction switch. The on button is a momentary switch that engages a magnetic switch (relay?) with a heavy 'thunk' noise. When the directional switch started to fail (literally began to fall apart internally) it was apparently not giving quite enough contact to maintain the circuit for the magnetic switch and it would throw out. Holding the 'on' button in would generate a succession of 'thunks' as the magnetic switch was trying to stay engaged but kept throwing out.
> 
> Jamie Durie...I have heard the name and I know he used to do something on TV but I'm not really familiar with him. Haven't heard the name for a while so maybe he's not so popular any more.



That’s exactly what mine is doing. Cool...sounds like the contactor is the culprit. 
Ah, yeah...he and I worked together here in the states years ago. Really good guy. Miss that crazy little Aussie! Lol I need to get there to visit.


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## Wizard69 (Oct 12, 2018)

Comments like these are very common with respect to Chinese lathes and is why I made my previous comment.   We had very similar problem with a small lathe at work where the push buttons just didn’t work reliably.    In one case I got some life out of the switch by shimming some parts to achieve better engagement until we had time to overhaul with real controls.  Long term a controls overhaul may be required!

The problem here though is we still haven’t nailed down root cause.  That can be difficult to do over the net but I wouldn’t be surprised one bit if the issue is in fact a switch someplace.  

The other gotcha that often shows up is loose or bad could connections.   I had one example of this at work the other day on a machine that ran for years without issue and then wouldn’t see that be switch input at the PLC.    Apparently it has a connection at a terminal made with the terminals set screw pressing against the wires insulation.  For whatever reason it ran for years like that and then decided to give upon the middle of the night.    Of course things like this aren’t often obvious unless you tear things apart.  




Cogsy said:


> Actually, I believe I confused myself and this was a different issue. The one I'm thinking of was a forward/reverse switch going bad and when I pushed and held the button in I would  often get the mag switch 'bouncing' in and out but not holding. The motor would start to spool up at this point. Sometimes it would engage, sometimes it wouldn't. As the switch failed over a couple of days it went from being a couple of clicks from the mag switch when trying to start to impossible to get running fairly quickly.


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## Wizard69 (Oct 12, 2018)

StephenZ said:


> That’s exactly what mine is doing. Cool...sounds like the contactor is the culprit.
> Ah, yeah...he and I worked together here in the states years ago. Really good guy. Miss that crazy little Aussie! Lol I need to get there to visit.



It could very well be the contractor, an auxiliary contact or even a contact in the thermal overload.    The problem with this Chinese stuff is the difficulty in getting the proper parts.  

This is why you often find the entire contractor assembly replaced on these machines with products that have higher local availability.   In that regard I like the Telemacanique (Square D) and Allen Bradley brands as we have good local supply houses.     In this day and age of mail order everything, people often ignore local suppliers but I like to think of them as members of the team.  

Some of the Japanese manufactures do really good controls but it is much harder to find local support.    We have done work with Automation Direct and the stuff they import but that has mostly been their very good drives, not the controls you would need here.  

I hope this doesn’t sound like a commercial, I just prefer local suppliers as much as possible.


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## StephenZ (Oct 13, 2018)

Ok...bear with me here. I'm losing my patience...lol. I took the original contactor apart and it had some parts falling out. I got it back together and it seemed to work ok. Suddenly, I had reverse spindle direction. no forward...still pretty exciting. I swapped the fwd/rev switch wires to see if the switches were bad. No. it still only wanted reverse. So I swapped the wires to the direction contactors to see if they'd allow forward. It popped the thermal overload breaker and now I don't have reverse anymore either.... Ok... I used the new CU-11 contactor and put it in place of the forward contactor. Still nothing...and no reverse still. Mind you, all this is still without the green 'power indicator' bulb even in the socket?! WTH? 

I also measured voltage from my transformer. With power switched on, it's in the 27v range. under load, it's 18-20v.. Does that seem like a low voltage that wouldn't hold the contactor closed?

Well, I have a new transformer, but the wire block is a little different. I hooked 220v up to what says 220/0 and it was giving me 28v output. Problem is there's no ground on the low voltage side, so I left it off. Again, no spindle movement... I'm so over this. Any thoughts on the correct wiring to this trans?
Old on right: wired 220v lines to 20&21
                        30 low v to the 2a fuse (5.5-6v?)
                        31 to thermal and on to everything (24v)
                        E ground


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## ignator (Oct 13, 2018)

StephenZ said:


> Ok...bear with me here. I'm losing my patience...lol. I took the original contactor apart and it had some parts falling out. I got it back together and it seemed to work ok. Suddenly, I had reverse spindle direction. no forward...still pretty exciting. I swapped the fwd/rev switch wires to see if the switches were bad. No. it still only wanted reverse. So I swapped the wires to the direction contactors to see if they'd allow forward. It popped the thermal overload breaker and now I don't have reverse anymore either.... Ok... I used the new CU-11 contactor and put it in place of the forward contactor. Still nothing...and no reverse still. Mind you, all this is still without the green 'power indicator' bulb even in the socket?! WTH?
> 
> I also measured voltage from my transformer. With power switched on, it's in the 27v range. under load, it's 18-20v.. Does that seem like a low voltage that wouldn't hold the contactor closed?
> 
> ...


In this thread and the related one, there have been schematics that show a transformer with a 6volt output winding. Your transformer does not have this (old or new). You must find or make a schematic diagram specific to your lathe. The marked up diagram I posted (#20 of this thread), I believe to be close to your lathe. But this only has one indicator lamp.
The "E" terminal is for EARTH ground, and is for safety only, in the event a winding faults to the steel laminated core. This earth ground wire should be connected to one of the screws mounting the transformer.
For some reason you think the "green 'power indicator'" has something to do with making this work. I think I recall you indicating there are 2 lamps, one comes on when power is applied, the other when the safety control circuit is enabled. Don't fall into a hole believing the lamp is the problem, as was indicated in the other post.
Can you please post a valid schematic that you believe your lathe has!
There is a VA (volt amps rating) required to pull a contactor solenoid mechanism closed. If you exceed the transformers capability you can get this operation (not pull in the contactor solenoid). This can be from a damaged transformer, as well a damaged contactor coil. For your lathe to operate, the power required from the transformer has to pull in 2 contractors.


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## StephenZ (Oct 13, 2018)

ignator said:


> In this thread and the related one, there have been schematics that show a transformer with a 6volt output winding. Your transformer does not have this (old or new). You must find or make a schematic diagram specific to your lathe. The marked up diagram I posted (#20 of this thread), I believe to be close to your lathe. But this only has one indicator lamp.
> The "E" terminal is for EARTH ground, and is for safety only, in the event a winding faults to the steel laminated core. This earth ground wire should be connected to one of the screws mounting the transformer.
> For some reason you think the "green 'power indicator'" has something to do with making this work. I think I recall you indicating there are 2 lamps, one comes on when power is applied, the other when the safety control circuit is enabled. Don't fall into a hole believing the lamp is the problem, as was indicated in the other post.
> Can you please post a valid schematic that you believe your lathe has!
> There is a VA (volt amps rating) required to pull a contactor solenoid mechanism closed. If you exceed the transformers capability you can get this operation (not pull in the contactor solenoid). This can be from a damaged transformer, as well a damaged contactor coil. For your lathe to operate, the power required from the transformer has to pull in 2 contractors.



Yes! sorry, I've calmed down after a night's sleep... Your schematic from #20 looks to be the one. I only have one indicator lamp, too. I agree with not thinking the light bulb is the problem, I'm just keeping it in the back of my head as I tinker. 
I saw from your #20 post, the KA is energized while no direction is selected, correct? Then, did you mean that when a direction is selected, KA de-energizes (mag releases) and the KA1 or 2 energizes? Was that the safety system you referenced? (I'm just trying to understand all of it properly). If that is the case, that's what happens. When power is turned on, the KA energizes...when a direction is chosen, KA de-energizes, but nothing happens. I felt like when I chose a direction, and KA de-energized, I could push in KA to get movement, not KA1 or 2. At any time with only power on and no direction selected, I can press KA1 or 2 to initiate the motor. 
The pathways and wiring all make sense as I look them over, I think I get lost with all the wiring that goes back and forth between the contactors. I assume it's done to prevent accidental spindle starts, switching directions accidentally, etc...for safety. I kind of wish I could just get new guts and wire it myself, so I know it all...
Thanks for dealing with me on this. I'm not used to needing help on anything...feels weird. 
-Stephen


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## BaronJ (Oct 13, 2018)

Hi Stephen,

I'm a bit late to this thread but have you actually disconnected the motor and checked that it runs properly when wired directly ?  The motor capacitor could have gone bad or a loose wire.


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## StephenZ (Oct 13, 2018)

BaronJ said:


> Hi Stephen,
> 
> I'm a bit late to this thread but have you actually disconnected the motor and checked that it runs properly when wired directly ?  The motor capacitor could have gone bad or a loose wire.



Welcome to the party..lol. I can manually engage the contactors and the motor jumps to life. Would it make a difference wiring directly? I can do that easily, but the motor seems ok.


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## BaronJ (Oct 13, 2018)

Hi Stephen,  Sorry I thought that I'd read that the motor had stopped running when manually closing the contactors.


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## BaronJ (Oct 13, 2018)

Hi Stephen,

Looking at post 20, I assume the correct circuit for your machine. Manually operating KAf or KAr should run the motor in either direction.  Without power via KA neither of the other contactors will pull in or hold in.
The power to operate KAf and KAr comes from the transformer low voltage supply.  Probably via the start and stop buttons.  One of which will be normally open and the other normally closed.
DO NOT OPERATE KAf or KAr TOGETHER !  They have a looped back contact that prevents them both from being energised at the same time.


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## ignator (Oct 13, 2018)

StephenZ said:


> Yes! sorry, I've calmed down after a night's sleep... Your schematic from #20 looks to be the one. I only have one indicator lamp, too. I agree with not thinking the light bulb is the problem, I'm just keeping it in the back of my head as I tinker.
> I saw from your #20 post, the KA is energized while no direction is selected, correct? Then, did you mean that when a direction is selected, KA de-energizes (mag releases) and the KA1 or 2 energizes? Was that the safety system you referenced? (I'm just trying to understand all of it properly). If that is the case, that's what happens. When power is turned on, the KA energizes...when a direction is chosen, KA de-energizes, but nothing happens. I felt like when I chose a direction, and KA de-energized, I could push in KA to get movement, not KA1 or 2. At any time with only power on and no direction selected, I can press KA1 or 2 to initiate the motor.
> The pathways and wiring all make sense as I look them over, I think I get lost with all the wiring that goes back and forth between the contactors. I assume it's done to prevent accidental spindle starts, switching directions accidentally, etc...for safety. I kind of wish I could just get new guts and wire it myself, so I know it all...
> Thanks for dealing with me on this. I'm not used to needing help on anything...feels weird.
> -Stephen


KA is used as a safety interlock, this ensures that your direction selector on the lathe apron is in the neutral position, the intent, that the spindle will not spin until you are "at the wheel" wanting it to go. Its intent is in the event of a power outage, the lathe will not come back on until you move that lever back to the off position.
So NO, KA must remain energized when you select a direction of spindle. If it does not, then there is some issue, either its coil has overheated and requires excess current from the 24 volt transformer to remain engaged, or the transformer overheated and can't provide the power to keep it engage, (or a loose connection), when you select either the forward or reverse contractor to engage (Km1, KM2). Loose connections can look the same. And as it was working before you brought it home, this is very possible. Or you are not powering it from the same voltage. I think you indicate this is a 220VAC system. If so, then ensure the motor is wired for 220. The nameplate shows Low and High voltage wiring chart, so ensure you have this correct. 
I've seen where they only change the wiring to the run windings, as the start windings are in the circuit for such a short time, that the motor design does not change them between high and low input voltage. If you haven't already looked up how the motor direction is changed, one of the windings, typically the start winding, has it's leads reversed, that is what the 2 contactors are doing (flipping the start winding connections). The start winding has a start capacitor in series, as well a centrifical switch that opens the connection to it after the motor has spun up to speed. You can typically hear this, as well when the motor is coasting to a stop, hear it click back closed.
If you look up "3 wire stop start circuit" with google, you will see what the KA relay circuit is doing. The coil can only get 24v power if the direction switch is not selecting FWD or REV. That is the 2 switches marked SA1  and SA2 on the diagram. That is what initially powers the KA solenoid coil to close the contacts. Note once this occurs one of the KA switches, then applies the power to the coil to keep it energized 
Quick note on start stop push button control:
(in a 3 wire start stop button circuit, the start switch, a normally open switch,  powers the relay coil , and an auxiliary switch of that relay, then keeps the power going to it through the stop switch which is normally closed, when you press stop, the power is removed from the coil). This KA circuit is very similar.

Then in series with the direction contactors is one of the 3 KA switch contacts. There is one in the circuit for REV coil circuit, and one for the FWD coil circuit.

Note that the SA1 and SA2 are what is called single pole double throw switches, as when you move the lever for forward or reverse, the connection that would normally power the KA coil, is opened, and the 24 volt from the transformer is redirected to the FWD, REV contactor coil, but since a switch contact of the KA relay latches the 24 volt to the coil, it stays engaged. And there as others have said, is an interlock to ensure you don't energize the FWD/REV contactors simultaneously. KM1 and KM2 are the coils for motor direction contactors, that you have figured out how to manually close, and have proven there is no issue with your motor.
If the KA relay ever opens, as you indicate, when selecting motor direction, the issue is either a loose connection or a bad KA coil, or 24 volt transformer.
Please check that the motor is wired for 220VAC. Hopefully you have all the wires still connected properly, then verify that KA can close, and does not open again when you select motor direction. If it does check the KA switch that closes to keep the power to the KA coil. Check what the 24 volt transformer voltage does when KA is energized, and you then energize KM1 or KM2 for motor power. If it does not droop excessively then either a loose connection or a bad coil needs to be determined. Check what the 24 volt is at these coils. You need to track down the fault.

Again KA must stay in the circuit as it has switch contacts in series with the motor contactor. You need to figure out why it is dropping out when you engage motor direction.


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## StephenZ (Oct 13, 2018)

Ignator, thank you for that! It all made sense and I'm going to start tracking down everything again, with a good plan this time. I'll report back with voltage readings and findings. Meanwhile, I managed to draw a wiring diagram for  my lathe. I hope I did a decent enough job on it. Oh, and the model of it is Harbor Freight#43681 12" x 37" gap bed lathe.


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## StephenZ (Oct 13, 2018)

So, with power on, no direction selected, the transformer has 22v coming out of #2 and 4v coming out of #1 and KA is energized.
When reverse is selected #2 is 24.7v and #1 is 1.4v   KA is de-energized
When forward is selected #2 is 25.5v and #1 is .75v  KA de-energized also
(I still have no light bulb in the power indicator...coming monday in the mail.)

EDIT: Good Lord. I put the old LED bulb back in and the light works...wth!? I've pulled the contactors out to check connections, but I'm going to do it again. stupid electrical gremlins.


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## StephenZ (Oct 13, 2018)

Ok. some tentative good news. I think it's figured out. (knock on wood) So the KA contactor was bad. I switched stuff around as I traced and tested all the wiring and put a new one in place and got reverse spindle to work. The light bulb is also working. Forward isn't working right now. I swapped the switches, and they're both good. I also switched the auxillary contactors on the direction contactors and still no forward. So far, I traced currents while the spindle is running and it seems like the forward contactor isn't getting the 'go ahead' from the reverse contactor via the 17 wire. I think. If that's the case, I think the reverse direction contactor has an issue. It runs fine for reverse, but isn't signaling the forward to go. 
Does any of that sound correct? It seems like the signals and currents from KA were correct...anything I'm missing?


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## ignator (Oct 14, 2018)

StephenZ; OK, a reply to post #37;
The KA relay, probably is not the problem, but the wiring to the hold switch, or that switch is preventing it from staying energized.
Also the schematic I've been using came from post #3 RM-MN, as he posted Harbor Freight schematic link to SKU: 43681.
You need to check the KA holding contact, and it's wiring, I don't think that relay is bad, as the coil pulls in. 




So look at this diagram again, note the  (top in this diagram) KA contact that is circled, this is either is oxidized, or the wires are loose. If you can take the relay apart, and check for the contacts being clean, if they are, you should be able to get low ohms measured when you manually close the KA relay solenoid. IF you do, check the wiring to ensure the 24 volts from the transformer is making there, and out to hold the KA coil energized.


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## ignator (Oct 14, 2018)

Reply to post #38;
Using the wire numbers from the diagram for the 43681 lathe, did you "mess" with any of the wiring going to the FWD/REV micro switches that the direction lever actuates?
As these are single pole double throw, there is a common connection, and a NO, NC (normally open, normally closed) terminal. If you swapped the wires on one of these, that can explain why you can't get forward.
Note the 24 volts from the transformer is connected to the common terminal of SA1, the normally closed terminal of this is connected to the common terminal of SA2, and from there the NC terminal is connected to the KA coil. This is the safety circuit that ensures you have the selector in a neutral (non FWD REV) position.
Note the NO terminals of SA1 and SA2 are connected to a KA relay contact, through an interlock contact to prevent FWD and REV from simultaneously being energized.  These are what power the KM1 and KM2 motor contactors. 
You need to follow the wiring diagram, and using the ohm meter of your VOM (or multi meter if you call it that), trace the signal path.

In your post #37 "22v coming out of #2 and 4v coming out of #1"  you must be using ground of the machine to measure, and not the terminal #1 from the transformer, this will not give the correct reference, but it's close enough. For the low volts, you should use one of the transformer leads for a reference for voltage measurement to the coils. That would be marked as a 0 (I think that's what it is, but might be a 4, as the scan quality is poor). Note this low volts is isolated from the AC mains power. Your old transformer had a chassis ground that was for isolation protection, the diagram shows this as a line between the primary and secondary windings. And shows AWG20 GREEN for the wire of this.


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## Anatol (Oct 16, 2018)

I'm looking in after being preoccupied for a week or so.

In post #28, you said
"Problem is there's no ground on the low voltage side, so I left it off."

Just in case you're working with inaccurate concepts - 
There is no such this as 'ground's an AC circuit. That is concept in DC, and its spurious anyway. 
In AC you have 'active' and 'neutral' (which is not 'ground). The only ground is the earthing of the chassis to ground for safety. (As ignator mentioned). In transformer, there is no conduction between primary and secondary windings (unless its an autoformer) . Electricity induces magnetism which indices electricity. 
So if you left the 'ground' off, you failed to make a circuit.

Ignator also mentioned " there have been schematics that show a transformer with a 6volt output winding. Your transformer does not have this (old or new)." 
So what happened to that 6v line - what was it doping? I suspect it was for a6v bulb,made obsolete by some fancy LED replacement (just a guess)

hope that's useful or at least interesting


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## lou (Oct 17, 2018)

Does your machine have a foot brake if so check that is not activating?


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## StephenZ (Oct 18, 2018)

Anatol said:


> I'm looking in after being preoccupied for a week or so.
> 
> In post #28, you said
> "Problem is there's no ground on the low voltage side, so I left it off."
> ...



Correct. I miss said that. I was referring to 'earth' on the transformer. 
The LED was a 24v bulb (very tough to find) that completes part of the circuit in the control panel. Strangely, the bulb worked when I put it back in the other day...after I ordered two new ones...lol.


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## StephenZ (Oct 18, 2018)

So, good news! I JUST got it running properly. So the final things I did, ended up being:
-rebuilt the KA relay, again...
-replaced the KM1 contactor (originally thought the switch was bad, but eliminated that and traced it down to the contactor itself.)
-found a loose wire connector that was in the FR-KM2-KM1 loop. 

I cannot express properly, how thankful I am to all of you on here. I have never been on a more willing and helpful forum in all my years...(not THAT many years yet, but at 45 there have been a few..lol.) Without all of your knowledge and help, I would not be in the, much more informed, position I'm in now...with a working lathe! I'm literally sitting here with my 10 year old son, explaining how rare it is to find people this willing to put in this kind of time on someone else's problems. Very cool. Thank you all!!


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