My lathe has gone catawampus

[Grahamshed]

My lovely 18 month old Jet 3520 lathe has died on me.
While I am waiting talk to Axminster on Tuesday I am wondering if anyone here has any ideas.

I was using it quite happily for an hour or so I turned it off by turning the speed down to zero while I went and picked up something heavy for SWMBO ( took 2 minutes or so ). When I turned the speed up again it came up to speed and then slowed down and died away. I turned it off by the NVR switch and unplugged and left it overnight until today.

I have just checked, fuse is okay but when I turn it on at the wall ( NVR still off ) I can hear a small crackle every second or so from the headstock/inverter area.

The one thing I know about electrics is to stay away from it as much as possible.

Any thoughts ?

 

[finneyb]

Could try dust removal from inside the headstock, disconnect from the el supply first. Otherwise I'd wait for Tuesday - Axminster will sort it I'm sure.

Its times like these that Axminster should have an emergency telephone helpline.

EDIT This thread may be useful http://www.sawmillcreek.org/archive/ind ... 15577.html

 

[sunnybob]

If the machine switch is off, but you hear a noise when the wall switch is turned on, the the NVR switch is faulty. There should be no power anywhere past that switch.
They are not user serviceable, but you could remove it from the machine and (with the wall socket unplugged NOT just switched off) check the wiring on the switch.
There are two in and two out. If you remove any of them, you MUST make sure it goes back in the hole it came from so take out one at a time to check condition. Make sure they are tight and look clean. Any sign of burning ,especially a smell of burning, and it has to be replaced.

 

[Grahamshed]

Thanks Finneyb and Sunnybob.

With the machine plugged in and turned on at the wall I still hear a click when the inverter comes on and get a display in the RPM window even with the NVR switch activated ( ie. turned off ). It has always been that way.

I have to admit that I have messed with the control switches by removing the switch panel as a whole and extending the wires so I can mount it in a remote switch box. I did this a while ago and it has been working fine up till now.

Finnyb's link to another post was very informative so heres hoping it is just the switch..... but you would think the switch would break upon use. the only switch I had touched at the time of the problem was the speed dial.

 

[sunnybob]

I'm confused.
You have an inverter where?
Assuming its a 3 phase machine being powered by a single phase supply?

The NVR switch should be before the inverter.
Sounds like you are describing the inverter switched from the wall, and the NVR being in line after the inverter?


Is the machine fitted with a 3 phase nvr switch?
More info needed.

 

[Grahamshed]

Hi Sunnybob
You now have me talking about things I know nothing about.
The lathe, A Jet 3520, has an inverter on the back of the headstock. On the headstock is ( was ) a switch panel containing a NVR push/ pull switch, a forward/reverse switch and a speed dial going down to zero ( Potentiometer ? ) The main input to the lathe is 240volt, i.e. single phase, but I have read somewhere that the actual switches wiring is 24 volt DC.

 

[RobinBHM]

'Catawampus' -thats a new word to me, I had to look it up, I see it means awry, askey, diagonal!

Unfortunately I dont have any answers regarding your lathe, I expect Axminster will though.

 

[sunnybob]

http://content.powermatic.com/manuals/1352001_man.pdf
This is the only wiring diagram I can find for a jet 3520 lathe.

If this is what you have then that push pull switch is NOT an NVR safety switch. Its switching the neutral only as most american equipment does. I cant find an inverter in the wiring diagram, how did you come to call it that? (assuming this is your lathe)

But anyway. If that switch is a push pull, then your problem is with the potentiometer control (speed wheel) They often burn out in one place only, usually the most used place. Do you normally turn it down to zero, rather than operate the main switch?

The crackling is the same as you hear on old radios when you move the volume wheel, and have to fine tune it. the wheel needs to be replaced, and although they are fairly cheap if you are not happy about doing that work its time to call axminster. its still in warranty.

 

[Grahamshed]

Hi again Sunnybob.
Yes that is the lathe and yes that is the wiring diagram I am used to.

On off switch not a NVR ? OK, I guess I just assumed that is what they fit.

Inverter ? This is from page 13 of that booklet you linked to.

Single Phase Operation
A three wire pigtail for use on 230 volt single phase power is attached to the inverter and may be “hard-wired” to the power source, or connected to a UL/CSA listed receptacle plug.

Could well be the potentiometer at fault, that was the only switch I touched but the 'crackle' was coming from the headstock area and the switch panel was at the other end of the lathe.

But I will be emailing Axi tonight , I dare say they have had this before

Thanks for your contribution.

 

[sunnybob]

ok, I've had another look, must admit I just scrolled straight to the wiring diagram. According to page 13 that joint block is the inverter. The machine can be wired single or three. I hate american wiring, they only use black for live, rarely have a neutral on three phase and chasing a circuit around a diagram used to wind me right up. Glad I dont have to any more.

In that case yes, its possible the inverter has burnt out.

 

[YewTube]

Just to clarify. The single phase mains is wired direct to the inverter and the three phase from the inverter to the motor.

Speed control, on/off and reverse, of the motor, are controlled by a low voltage circuits to the inverter.

If you switched the inverter on and off then you would have to wait for it to boot every time.

The push/pull switch tells the inverter to disconnect the 3 phase from the motor.

The inverter is your NVR switch. i.e. if you loose the mains supply it should reboot to OFF.

The 'small crackle from the inverter' mentioned in your OP does not sound promising.

I would check with Axi.

Bill

 

[sunnybob]

you obviously have a better working knowledge of the machine than me (couldnt be worse as I havent even seen one), but are you sure that push pull is an NVR?
The wiring diagram only shows two wires.
I havent seen a No Voltage Release switch with only two wires

 

[YewTube]

The push/pull is not an NVR. It works a low voltage to tell the inverter to do the disconnect.

It is the inverter, as an entity, that acts as an NVR switch by the fact that it reboots if you disconnect then restore the power.

Think of the inverter as your computer. If you are reading this in your browser and you loose power then next time you power up you will go to your default settings and not this page.

Hope that helps to clarify.

Bill

 

[sunnybob]

ok, that helps. I know almost nothing about inverters.

But I'm still confused as to where the nvr system is. If you disconnect from the wall, and the inverter loses power and the motor stops, where is the interrupt? What I mean is if the push pull switch isnt moved, what stops the machine from restarting by itself when the wall power is restored?

 

[YewTube]

The inverter=NVR switch. (Defined as 'when the power comes back it don't run)

Guessing now cos I'm too lazy to find the manual for the inverter. I suspect the inverter will reboot to it's default state and wait for a change of state from the on/off switch before it will start up the motor.
In the immortal words of the 'IT Crowd' I think you will have to, "Switch it off and on again".

Bill

 

[sunnybob]

Grahamshed, we (I) need to know. Under normal useage, if its disconnected from the wall, do you need to operate the push pull twice before it works?

 

[Grahamshed]

This is all above my head but makes interesting reading and I am appreciating it.
I have, on occasions, stopped the lathe by turning down the speed dial and then unplugged it without pushing in the on/off ( not NVR ) switch. When I pkug the lathe in again I do indeed have to push the switch in and pull it out again.

 

[sunnybob]

Ok, now we're learning.

The switch itself is NOT an NVR switch ( I knew it couldnt be because it only has two wires). The automatic disconnect is in the inverter (which I know (knew) nothing about).

as a future point, what youre doing is is stressing the inverter. You should use the switch not the speed control when you turn the machine off.

 

[Grahamshed]

as a future point, what youre doing is is stressing the inverter. You should use the switch not the speed control when you turn the machine off.

How so ?
The speed dial takes the speed down to zero, thereby stopping the lathe. I use the on / off switch at the end of the session (usually) but not when I am stopping the wood spinning so I can see how its going or what have you. To do so could be dangerous as it would start again at full speed.

 

[sunnybob]

My meaning is that you can by all means slow it down to a stop, but when closing down for any length of time then use the switch to remove power from the inverter. otherwise the inverter is using a small amount of power all the time untill the wall switch is turned off.