Laser controller starts up when usb is plugged in but main power off

Community Laser Talk
1

Don’t know if anyone can help me with this weird one (to me anyway)

I’ve moved to a new unit and just finishing up setting the lasers up.

When I turn on the pc the big lasers controller starts up and tries to do the usual reset, but the mains is not actually plugged in so of course nothing moves. If I pull out the usb the controller goes off.
It never did this before, only ever coming alive when the main power was switched on.

Any ideas? Is there a setting somewhere that has reset while it’s been powered down for a few weeks?

Many thanks. Neil

2

How do you know what it’s doing if there is no movement?

I’d guess you have a ground/power loop that exists between the pc and the machines power. One of them is probably not polarized correctly.

You might have to give us more information to get this squared away.

:smile_cat:

3

I know because it says resetting on the screen

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Nothing moves as it’s not plugged into the mains, but the reset finishes and gives me x and y and z positions which are no where near where the head actually is off course.

4

If there is no mains power where is the controller getting it’s power?

The mains are not connected to the machine?

I see it resetting, it should fail to home, I think that’s the esc to continue job.

I have mine via Ethernet, but I can only think it’s getting some kind of connection to power via the usb. I’d assume via the ground connection of the usb.

I really can’t see how this would happen… are you depending on a switch for power or does power come on when the usb is plugged in?

These need 24V to operate, so I wonder.

:smile_cat:

5

The mains plug is on the floor so definitely no power coming from there, only source is the usb cable. It’s only the controller coming on. The cooler is plugged into the back of the machine and that doesn’t come on.
If I plug the main power in everything comes on and it resets as normal all moving etc.

I just don’t know why the controller is coming on when the USB is in. I can unplug the usb it goes off and plug it in comes on, every time.

Must be a setting somewhere.

6

It could be using the 5V from the usb to power only the display.

Can you move it to Ethernet?

Can you examine the actual controller in the electronics bay and see if it indicates anything?

:smile_cat:

7

That’s quite common, I’d say. Most controllers (at least the diode laser ones) turn on when powered by USB. That’s no issue, the controller is just running because the logic power is 5V. If you have a new device, this might be wired differently than the others. Newer designs have the power switch in front of the logic circuit.

If you don’t like the effect, cut the VCC line within the USB connection (or, less drastic, put a piece of tape on the VCC pin in the USB connector).

8

ok, Problem solved…and such a simple mistake!!

There are 2 USB connections on the laser, one says USB, the other says PC. I plugged into the USB as it’s a USB lead, but apparently USB is for a pen drive to load in files. the PC one is the connection from the PC of course.

Thanks for the replies, so simple in the end

2 Likes
9

Were you able to control the laser while plugged into USB labeled port?

10

Don’t know the answer to this as I didn’t try.

The extraction is not sorted yet so didn’t get as far as running it. It was the fact it was coming on everytime I started the computer for another laser machine that was strange at the time.

1 Like