Emco PC120 Turn

[Chaz]

Chaz most soldering irons are earthed so if you touch any live point you are basically shorting it to earth.. also those PS seem very expensive for a 24V 5A supply even a RS one like this http://uk.rs-online.com/web/p/din-ra...plies/1238020/ is cheaper.

Thanks. Ive got similar on my other machines. I always believed that the iron is 'floating'.

[Clive S]

Thanks. Ive got similar on my other machines. I always believed that the iron is 'floating'.

Well I shouldn't really admit it but in the good old days of valves tv's the first thing we did was cut the earth off the iron one of the reasons was that one side of the mains was connected directly to the chassis and you generally worked on them switched on. I am in no way telling anybody to cut the earth off anything.

[Chaz]

Well I shouldn't really admit it but in the good old days of valves tv's the first thing we did was cut the earth off the iron one of the reasons was that one side of the mains was connected directly to the chassis and you generally worked on them switched on. I am in no way telling anybody to cut the earth off anything.

Ye, we did that too when I was an apprentice.

[Chaz]

So I emailed the local company for these PSUs. Keep in mind I didnt buy the units from them so I was not sure if Id even get a response.

Received this:-

The solder tip of your iron will be earthed and this is a different potential to the Ov rail which is not really “0v” but simply a DC return for the +DC rail and is therefore floating with respect to Earth. I am not sure of the effect on the PSU by doing what you have done – usually a thermal trip / breaker will have activated but if it isn’t anything obvious then all you can do is speak to the manufacturer which is not us, we simply distribute. The manufacturer is a company called EPLAX in Germany and you need to call them

So I have a few options. Let's assume they are faulty. I need roughly 10A if I do a like for like replacement although I am sure that the smaller driver and board take less than 2A. I could also increase the Voltage on the two main axis steppers. Would higher voltage be better or just remain with 24V all round?

Thanks

[m_c]

Without reading back through the thread to see what you have or have not changed, can the stepper drivers handle the extra voltage?

I'd suspect they've just used a generic power supply, rather than have two different ones, so you will most likely get away with a smaller one if one only powers a single motor.

[Chaz]

Without reading back through the thread to see what you have or have not changed, can the stepper drivers handle the extra voltage?

I'd suspect they've just used a generic power supply, rather than have two different ones, so you will most likely get away with a smaller one if one only powers a single motor.

I dont have the motor spec and I am reluctant to start removing bits. Probably the easiest to do is simply put back a 24V 10A supply which will cover all my needs. I have a 24V 5A already which is being used for another machine - ill move this across, make sure it all works and then buy a larger din rail unit and rewire where needed.

[Chaz]

Ok, using a 5A PSU and a new BOB, we are back to where we were. However, I cannot get the relays to switch.

Click on coolant, the 5V relay on the BOB clicks, light comes on, IN1 (Input 1) on the Relay board switches. The problem is that the relay state on the relay board doesnt change. If I remove the jumper (what does it do?) the relay makes / breaks but that is manual. If I try and bridge to the other side the BOB boards dim and its clearly not happy.

Any ideas? My 5V light on the PSU is also not active however I can measure 5V (PC voltage) across the pins. Is my wiring correct?

[Chaz]

OK, its working. Looks like the relay board must have been damaged. Had bought a 2nd one as they were cheap. Now works :-)

Wow, what a mission.

[Chaz]

Ok, its working however at startup the boards 'click'. It did not cause a problem at first but now the coolant pump starts / stops as the relays change state.

Any idea what can be causing this? I tried a different 5V supply. I believe the 24V supply can offer enough current. I cant see any voltage drop as such.

Could it be Mach 3 initalising as the PC boots up? Not sure if I can create some form of 'dont power anything till everything is ready' steady state. The PC currently is fed from the same power as the CNC. Perhaps I should power the PC on its own and see if this still happens during the machine start up.

Once everything has been booted and settled, the clicking goes away.

[m_c]

Are you using a charge pump?
If not, it sounds like the parallel port doing random things as things boot up.
If you've not got a charge pump, a quick fix would be an extra switch to keep the lathe powered of until the PC has booted. It's not ideal, but it would work, provided you remember to turn things on in the correct order.