Nova DVR 3000 lathe tripping rcd

[gregmcateer]

So my cunning plan to do a bit of turning today literally went pop.

Switched on the lathe and the mcb and rcd tripped.

As a non electrical bod, is there anything specific I should look for, before I do some terrible damage, or should I just cry a bit, before starting to put spare pennies in the piggy bank for a replacement?
TIA
Greg

 

[NOTTNICK]

Hi Greg
I have replied via mail link too.
As you know, my Nova DVR 3000 also went wrong.
Nova are very helpful, if it is the PCB they'll replace it with a new / updated one for about £400 + postage. They won't consider fixing it.
I was really lucky as someone suggested a PCB repairer (I never knew they existed).
It turned out that one of the microprocessors was overheating after about 10 minutes - amazing that they found it! I went along and the way they found out was by spraying coolant on it, then it kept going.
Equally amazing is that chips are fairly generic. They replaced it - not a Nova chip, I think one that is / was fairly common.
I think it cost about £50.
They were amazing, a proper old-school electronics workshop. Workbenches covered in wires and bits and pieces but skilled people.
They had never repaired a lathe before, but of course it was the electronics they looked at.
I really hope you get it fixed as it is such a good lathe.
Nick

https://www.greasley.co.uk/

 

[gregmcateer]

Thanks Nick.
Cheers for the link, too.
Greg

 

[Adam Pinson]

Hi Greg
I have replied via mail link too.
As you know, my Nova DVR 3000 also went wrong.
Nova are very helpful, if it is the PCB they'll replace it with a new / updated one for about £400 + postage. They won't consider fixing it.
I was really lucky as someone suggested a PCB repairer (I never knew they existed).
It turned out that one of the microprocessors was overheating after about 10 minutes - amazing that they found it! I went along and the way they found out was by spraying coolant on it, then it kept going.
Equally amazing is that chips are fairly generic. They replaced it - not a Nova chip, I think one that is / was fairly common.
I think it cost about £50.
They were amazing, a proper old-school electronics workshop. Workbenches covered in wires and bits and pieces but skilled people.
They had never repaired a lathe before, but of course it was the electronics they looked at.
I really hope you get it fixed as it is such a good lathe.
Nick

https://www.greasley.co.uk/

Thanks for this link, good to know if anything happens in the future

 

[Richard_C]

The MCB is an overload protection, the RCD is a leakage protection.

In non electrical terms, taking your non-electrical bod words literally, (apologies if you know this stuff already) imagine a pair of water pipes one 'up' one 'down' with a coil of smaller diameter pipe joining them at the top. The MCB bit is what says "NO" and closes a valve if you try to send too much water up the pipe. The RCD bit compares the flow up and the flow down, and if they are different by even a tiny amount says 'something's not right' and shuts it down.

Both have a purpose. An MCB won't 'see' a small leak, an RCD will: an RCD won't 'see' an overload, and MCB will.

Coming back to electrics, say you have a 5 amp MCB (likely its 15 amp on your circuit) it won't trip with a 2 amp 'leak', but 2 amps going through a body is plenty enough to kill you. An RCD will see a tiny leak to earth, milliamps passing through a bit of a person or current leakage across a damp patch and trip very quickly. That's why we have both.

If both tripped at once on startup it sounds like a big 'leak to earth' fault rather than something like a circuit board overheating or drawing too much current. Likely to have some visible scorching if its inside a control circuit. I would first look for an obvious basic fault - loose wire in the terminal box, crud or moisture in the switch, fault in the switch, lead/connections to motor, maybe even damage to the lead. Sometimes the momentary overload of an old tungsten bulb blowing will trip out the 5a MCB on my house circuits. Is it hard wired in or via a plug? Test the plug fuse as well, that might have blown. Maybe not, MCBs and RCDs act much faster than a fuse. Oh, and unplug the lathe and reset the breakers, plug something else like a lamp or drill in and test. The fault might not be the lathe although that's unlikely as they tripped when you switched it on.

 

[gregmcateer]

That's a brilliant explanation Richard, Thank you. I really appreciate the time you've taken and I actually understood it!

I will start going through the obvious bits first and work through in stages. It's not hard wired, but on the cable that looks like a D at the lathe end - like the old' kettle' leads on a computer PSU.

Thanks again and I'll update once I've gone through steps

Greg

 

[NOTTNICK]

The MCB is an overload protection, the RCD is a leakage protection.

In non electrical terms, taking your non-electrical bod words literally, (apologies if you know this stuff already) imagine a pair of water pipes one 'up' one 'down' with a coil of smaller diameter pipe joining them at the top. The MCB bit is what says "NO" and closes a valve if you try to send too much water up the pipe. The RCD bit compares the flow up and the flow down, and if they are different by even a tiny amount says 'something's not right' and shuts it down.

Both have a purpose. An MCB won't 'see' a small leak, an RCD will: an RCD won't 'see' an overload, and MCB will.

Coming back to electrics, say you have a 5 amp MCB (likely its 15 amp on your circuit) it won't trip with a 2 amp 'leak', but 2 amps going through a body is plenty enough to kill you. An RCD will see a tiny leak to earth, milliamps passing through a bit of a person or current leakage across a damp patch and trip very quickly. That's why we have both.

If both tripped at once on startup it sounds like a big 'leak to earth' fault rather than something like a circuit board overheating or drawing too much current. Likely to have some visible scorching if its inside a control circuit. I would first look for an obvious basic fault - loose wire in the terminal box, crud or moisture in the switch, fault in the switch, lead/connections to motor, maybe even damage to the lead. Sometimes the momentary overload of an old tungsten bulb blowing will trip out the 5a MCB on my house circuits. Is it hard wired in or via a plug? Test the plug fuse as well, that might have blown. Maybe not, MCBs and RCDs act much faster than a fuse. Oh, and unplug the lathe and reset the breakers, plug something else like a lamp or drill in and test. The fault might not be the lathe although that's unlikely as they tripped when you switched it on.

This is really interesting, thanks for the enlightenment.

 

[gregmcateer]

Well.
That's weird. Went into the garage and thought I'd just switch on to see if everything popped, before starting fault finding.
Click, start-up tune and ready to go!
Still suspicious, I've carefully vacuumed all around, checked fuses, etc and no obvious burns, wear, etc anywhere.
Lathe spun up as normal.
I'll keep my fingers crossed.
Thank you to you good folk for your prompt and informative assistance.
Cheers
Greg

 

[Richard_C]

Lucky you. Odd things can happen, at least you know the mcb and rcd breakers work as they should.

Maybe there is a no longer extant spider which took a momentary 15 amp current.....to misquote Apocalypse Now "I love the smell of smouldering arachnids in the morning".