Harborfreight 12x36 lathe wireing

[StephenZ]

If the plug was arching then it is probably the root of the problem not the contactor. Also use the drawing that was sent with the machine. If your machine does not match the book then someone likely changed something. To best repair the machine, restore the wiring to match the drawing in the book.

Sorry, I wasn't clearer, my plug wasn't arcing like the example...just the general issues with the contactor de-energizing. I have the wiring diagram in the other response, and it's all that can be found, unfortunately. fairly useless. But I'm almost 100% certain the guts were never touched...until I started playing electrician..:-/.. I bought this from the original owner who barely used it over the years.

 

[Anatol]

I got it running. The problem turned out to be a bulb in the power start button I was waiting till I got it running to replace. I blew it well playing with the new transformer and looking over the diagrams it is part of the coil circuit. I don't know how I missed it before. Now just to order a new power start button. Thanks for all the help

Yeah, zombie thread, but I have roughly the same late, with Frejoth badge. I did a bunch of research a year or two ago, because I had a similar power problem. It was also badged Grizzly, Jet And Acra, and a couple of others. I found the original manufacturer - in China. As I *recall*, the bulb is the trick, its wired in series with one off the relay coils. So if the bulb blows, no power to the coil. Something like that.

Here is a manual with a writing diagram, same, worse or better than the one you have? oops, too big to upload, here are the pages.

 

[cds4byu]

OK, I've looked at your diagram, and looked at my manuals (an Enco lathe, not a HF, but the same basic diagram). I think I've pieced together the way the diagram is supposed to work. So here's my explanation.

Indicators:
HL1 is the power connected indicator. it should be on whenever the lathe is connected to power. If it's not on, there are three possibilities:
a) Lamp is burned out
b) FU2 is blown
c) Transformer is bad.
To test the transformer, I would disconnect FU2 and measure voltage between ground and the connection that goes between FU2 and the transformer. It should have 6 V.

HL2 is the lamp that tells you the lathe is energized. It should be lit whenever KM1 is active.
If it's not lit after you push the Start button, then you have a few possibilities:
a) HL2 is burned out
b) KM1 contacts have high resistance
c) FU2 is blown
d) Transformer is bad.
My first test of this circuit would be to push the power button, then measure voltage from ground to
i) FU2 connection to transformer -- should be 6V
ii) FU2 connection on other side of transformer -- should be 6V
iii) HL2 connection that is not to ground -- Should be 6V. If this is 0V, it probably means that KM1 is not energized. If this is between 6 and 0 V, it probably means that the contacts on KM1 have high resistance. You might be able to clean them with contact cleaner.

Switches:
SB2 is the power on switch. When this switch is depressed, current flows through the normally-closed SB1, the momentarily-closed SB2, the forward-reverse switch SA, and the E-stop switch FR to the KM1 coil. You can see if the coil of KM1 is energized by measuring the voltage from point 6 to ground. Should be 29V. If it's zero, you have a problem. Now it's time to trace the voltage through all the switches.

Once SB2 is released, it's now directly bypassed because one of the relays on KM1 jumpers across both SB2 and SA.

SB1 is the power off switch. When depressed, it interrupts the current to KM1 and shuts down the power.

SA is the reverse switch. In the neutral position, it connects the two pins on the left-hand side of the diagram. I think they are 5 and 6, but it's hard to read the diagram. In my diagram it is 5 and 6. In the forward position, it connects pins 1 and 2, which energizes KM2. In the reverse position, it connects pins 3 and 4, which activates KM3.
Note that when KM2 activates, it opens up the contactor on circuit 13-10 and prevents KM3 from activating simultaneously. Similarly, when KM3 activates, it opens the contactor on circuit 7-Z and prevents KM2 from activating. If the contactors between 7 and Z or 13 and 10 have high resistance, the lathe will not work properly.

SB3 is the inch switch. It momentarily causes KM2 to close.

FR is the emergency stop switch. It interrupts the power to KM1 and to the permanent motor connections S1 and R. By interrupting the power to KM1, it also interrupts the power supply to both KM2 and KM3.

Contactors:

KM1 is the main power contactor. It powers lamp HL2 and locks itself on with the contactor between circuits 3 and 5.

KM2 is the forward drive contactor. It connects AC line S to S1 and Z2, and line R to Z1. It also locks out KM3 by opening the contactor between 13 and 10.

KM3 is the reverse drive contactor. It connects AC line S to S1 and Z1, and line R to Z2. It also locks out KM2 by opening the contactor between 7 and Z.

Note that in both forward and reverse, Line S connects to S1. Unless the E-stop is pressed, Line R is connected to U1. The motor is reversed by reversing the connections to Z1 and Z2.

List of Circuits:

0. Low-voltage AC Ground. Connects to transformer, HL1, HL2, KM1 coil, KM2 coil, and KM3 coil.
1. Unfused 29 VAC. Directly off of transformer. Connects between transformer and fuse FU1.
2. Fused 29 VAC. Connects between FU1 and switch SB2.
3. Fused and switched 29 VAC. Connects SB1, SB2, and one contactor from KM1. We'll call this contactor KM1A.
4. Momentary 29 VAC. Connects between SB2 and SA terminal 6. 29 VAC, but only when SB2 is pressed.
5. Controlled 29 VAC. Connects between KM1A, SA terminal 5, one pole of FR (we'll call it FR-1), SA terminal 1, SA terminal 3, and SB3. This is hot whenever KM1 is active.
6. KM1 supply. Connects between FR-1 and KM1 coil.
7. KM2 unswitched supply. Connects between SA terminal 2, SB3, and KM3 contactor (we'll call it KM3A).
10. KM3 switched supply. Connects between KM2A and KM3 coil.
11. Unfused 6VAC. Connects between tranformer and FU2.
13. KM3 unswitched supply. Connects between SA terminal 4 and KM2A.
14. Fused 6VAC. Connects between FU2, HL1, and a contactor from KM1 (call it KM1B).
15. Fused and switched 6VAC. Connects between KM1B and HL2.
Z, KM2 switched supply. Connects between KM3A and KM2 coil.


Your specific problem, that KM1 de-energizes when the lathe is put into forward or reverse, is most likely due to high resistance in KM1A, in my opinion. WHen the other contactors draw current through KM1A (either KM2 or KM3), it causes a voltage drop that then makes KM1 no longer be energized. I'd look for some contact cleaner and try to clean the KM1A contacts.

But at the very least, you can check voltages. Make sure that you measure all voltages relative to circuit 0.

 

[StephenZ]

Holy Moly, cds4byu!!! You're like an internet superhero! I haven't gotten to read through all of it yet, but I'll sit down with my machine tomorrow and run the tests. Amazing. I can't thank you enough for putting all this down for me to go through. I think, just with my random testing of lines, I've tested most of these, but now I can go through and check them all off one by one. I've traced all the wires and figured out what most of them do...it's really great to have your explanation to fill in all the details. I'll master this, yet! LOL.
My two biggest issues now are the fact that I blew out the green indicator light and it may have killed the transformer. I was getting 28v before and now I'm only getting 18v. Any chance that's due to something else, or am I ordering a new transformer, too? Ugh.

Anatol, thank you for posting those diagrams. Yes, mine looks very similar to those pics! I only have one fuse, but the rest is basically the same. Thank you!!

 

[Antonio]

Ciao jdoocol4 ho dato un occhiata lo schema elettrico del tornio ,io direi che la prima cosa da fare e controllare la tensione d'uscita dal tc con un tester che dovrebbe essere 29V. se cè tensione controllare sempre con il tester la tensione tra 0V e SB2 se non cè in pulsante di EMERGENZA e interrotto deve essere normalmente chiuso NC. se tutto e a posto prova a ponticellare dal punto SB2 come da schema del tornio sul 5 dovrebbe eccitarsi KM1 se non si eccita e interrotto FR oppure la bobina e bruciata,
Se tutto ok può essere SA chè non funziona o il pulsante MARCIA contatto 3/4 controllare tenendo premuto con un cacciavite KM1 se il contatto 3/5 del KM1 chiude.
SE invece con il pulsante marcia il KM1 chiude e si accende HL2 i guasto può essere SA contatto 5/7 se no parte il motore in un senso e SA 5/13.
Fai queste verifiche e fammi sapere Ciao ANTONIO da ITALY

 

[rockman96]

Buy an AC Tech VFD, get the simplist and most basic one that you can find... pitch all the old controls, and don’t look back. VFD’s are awesome... not too expensive, give infinite control over what you have, and eliminate all the issues compared to what is on budget machines.

 

[cds4byu]

Holy Moly, cds4byu!!! You're like an internet superhero! I haven't gotten to read through all of it yet, but I'll sit down with my machine tomorrow and run the tests. Amazing. I can't thank you enough for putting all this down for me to go through. !

Thanks for the kind words. It's kind of a fun challenge to work out Chinese wiring diagrams. They follow some different standards than US diagrams, so it takes a bit of time...

My two biggest issues now are the fact that I blew out the green indicator light and it may have killed the transformer. I was getting 28v before and now I'm only getting 18v. Any chance that's due to something else, or am I ordering a new transformer, too? Ugh.

Anatol, thank you for posting those diagrams. Yes, mine looks very similar to those pics! I only have one fuse, but the rest is basically the same. Thank you!!

It seems relatively unlikely to me that you have destroyed the transformer. They are pretty robust, and also fuse protected. But I guess anything is possible.

A couple of suggestions:

1) Remove the fuse, and measure the voltage at the transformer. Is it 28V now?

2) Make a sketch of your wiring as observed on your machine. I note in your photo that the crimped-on connectors have circuit numbers (3, 5). If you will sketch the wiring you actually have, I'll try to figure out if it's the same as the drawings posted or if it's different. You mention at least one difference -- you only have one fuse. Others have suggested that the indicator light might be in series with the switch, which is different from the drawing. You hint that you may only have one control voltage coming off the transformer (with only one fuse), so I don't really know what's going on. If you get me a sketch, I'll figure out how I think it should work, and then we'll have some real troubleshooting steps, rather than just measure and hope.

HTH,

Carl

 

[ignator]

Buy an AC Tech VFD, get the simplist and most basic one that you can find... pitch all the old controls, and don’t look back. VFD’s are awesome... not too expensive, give infinite control over what you have, and eliminate all the issues compared to what is on budget machines.

That would be a solution for a 3 phase motor. The harbor freight and other derivatives are single phase. In my shop, I've replaced all the single phase motors with 3 phase, and used dedicated VFDs on them. And I set them up so the LED display indicates spindle RPM.

 

[StephenZ]

I've run through all the wiring and everything seems to be clean and hooked up properly, but without the LED in the power light, I'm stuck. I have one on order, along with a new transformer. The trans keeps giving different readings and it didn't used to. It's also making some nice loud buzzing/humming noises... With all the info you've provided, it really seems like that main relay/contactor isn't holding itself once a spindle direction is chosen. I have one of those coming, too. Hopefully, in a week or so, I can put the new parts in and start making a mess! Thank you for all the help with this! I'll check back in and update when I get the parts in. Maybe someone else will benefit from the info, as well.
-Stephen

 

[Anatol]

Stephen and Carl

I've run through all the wiring and everything seems to be clean and hooked up properly, but without the LED in the power light, I'm stuck.

The trans keeps giving different readings and it didn't used to. It's also making some nice loud buzzing/humming noises...

Maybe someone else will benefit from the info, as well.

Thanks for the kind words. It's kind of a fun challenge to work out Chinese wiring diagrams. They follow some different standards than US diagrams, so it takes a bit of time...

All confidence in Carl who has put more thought into it than I. I admire his dedication in deciphering Chinese circuit diagrams. I'm a bit baffled by the chinese diags too. Thanks for decoding the letters (FM, KR, SB etc). My manual (helpfully ) didn't have a key. I assume S+R are Active and Neutral.Carl, will you post your diagram?

The transformer has two 'center' taps, for ~24v, and ~6v, 24 seems to be unused ! So its 28v output, with a little 6v feed. for lights HL 1,2. But of course its still AC. Note In my diagram, its 220v AC, but presumably for US its 120. A 220 would mean output voltages were halved.

I'm not seeing the LED on my diagram, but LED is a DC device and I don't see rectifier, or even diode. I was about to say you could put a 6v flashlight bulb in there. Or a 12 v auto panel bulb, it'll be dim but it will work. IIRC, mine, older, has a bulb.

If necessary, you could make a little 6V dc circuit with a few diodes and a 7806.

Transformers can be found on the surplus market cheap, you have to find something compatible tho. I use Allelectronics, they're in Van Nuys, and good catalog online, and stuff is pennies on the retail dollar.

 

[StephenZ]

Stephen and Carl



All confidence in Carl who has put more thought into it than I. I admire his dedication in deciphering Chinese circuit diagrams. I'm a bit baffled by the chinese diags too. Thanks for decoding the letters (FM, KR, SB etc). My manual (helpfully ) didn't have a key. I assume S+R are Active and Neutral.Carl, will you post your diagram?

The transformer has two 'center' taps, for ~24v, and ~6v, 24 seems to be unused ! So its 28v output, with a little 6v feed. for lights HL 1,2. But of course its still AC. Note In my diagram, its 220v AC, but presumably for US its 120. A 220 would mean output voltages were halved.

I'm not seeing the LED on my diagram, but LED is a DC device and I don't see rectifier, or even diode. I was about to say you could put a 6v flashlight bulb in there. Or a 12 v auto panel bulb, it'll be dim but it will work. IIRC, mine, older, has a bulb.

If necessary, you could make a little 6V dc circuit with a few diodes and a 7806.

Transformers can be found on the surplus market cheap, you have to find something compatible tho. I use Allelectronics, they're in Van Nuys, and good catalog online, and stuff is pennies on the retail dollar.

Yes! Thank you Carl for the unbelievable work you put in deciphering the schematics!
And Anatol, thank you, too, for troubleshooting the insanity!

Ah, wish I knew about the Van Nuys place. I just ordered an exact replacement online. not bad, though.
Actually, the bulb from the light is 24v, which I couldn't find anywhere by itself..new entire light was only $10, though. The part I don't fully understand is how the front control panel works. The light and power knob seem to have current going to both sides of the switch at different voltages...when turned on, it changes, yet again. Is that how the low voltage circuit works, in that loop? maybe it does make sense...maybe I'm jsut hungry..LOL.

Where in LA are you, Anatol?

 

[cds4byu]

Stephen and Carl

All confidence in Carl who has put more thought into it than I. I admire his dedication in deciphering Chinese circuit diagrams. I'm a bit baffled by the chinese diags too. Thanks for decoding the letters (FM, KR, SB etc). My manual (helpfully ) didn't have a key. I assume S+R are Active and Neutral.Carl, will you post your diagram?

S and R are two legs of the 220V. Because the motor is 2Hp, it's 220 even in the US. No neutral on 220; neutral goes halfway between the two legs and gives two 110V circuits.

Carl

 

[cds4byu]

Stephen and Carl
Carl, will you post your diagram?

Ok, here are my diagrams. A bit of terminology:
R, S, and T are the input three phase wires.
U, V, and W are the motor three phase wires.

For single phase, R and S are the input, even though for single phase 100 we should call it L and N (line and neutral).
For the single phase motor, U1 and V2 are the run winding, and Z1 is the start winding for 220 V, while Z1 and Z2 are the start windings for 110 V.

The numbers at the top of the page on the wiring diagrams represent "Nets", or electrical points that are connected by wires. The nets are shown in the wiring diagram by uncircled numbers.

Circled numbers on the wiring diagrams are terminals on a switch or contactor.

The parts list shows the parts for my lathe; they could probably be used for most lathes 13 inch or smaller.

HTH,

Carl

 

[cds4byu]

SB1 is the power off switch. When depressed, it interrupts the current to KM1 and shuts down the power.

FR is the emergency stop switch. It interrupts the power to KM1 and to the permanent motor connections S1 and R. By interrupting the power to KM1, it also interrupts the power supply to both KM2 and KM3.

Two mistakes in my circuit description.

SB1 is the E-stop switch.

FR is a thermal relay that shuts the system down if the motor draws too much current.

Sorry about the noise.

Carl