GT2560 Question

[awdorrin]

Can the GT2560 control board be powered with just a USB cable? (For programming and configuration, not operating the printer motors/etc)

I am finding that if I power off the printer power supply, the GT2560 will, most times, stay on via the power supplied by the USB cable.
I have experimented and find that, after a few minutes, I cannot turn the GT2560 back on, through the USB port alone.

I have checked with a USB meter and find that when connected, the GT2560 pulls the voltage on my powered USB hub down to about 4.8V, with a current draw of around .25A.

While the printer power supply is on, the voltage is 5.0 @ 0A, after I turn the power supply off, the USB power measures around 4.92V at 0.11A.

Just curious what the normal operation of the GT2560 should be.

Thank you
-Al

[Mark]

yes it can be powered via the USB. And the regard to the voltage, how about change another USB port on your computer?

[awdorrin]

I have tried multiple USB Ports on two different computers. USB cables of various lengths, and even put a powered USB hub in the middle, as well.
Seems to be the same behavior each time.

Strange... not sure if I have a problem, or just a finicky board.

[awdorrin]

Ok, I have the printer wired up like this:

[Printer]<--USB Cable-->[Drok USB Meter]<->[USB Hub]<--USB Cable-->[Computer]

The USB Hub is a Sabrent USB 2.0 hub, with power switches,powered by a 2.5A power adapter.

I'll startup the printer's power supply and wait until the LCD displays. I will then push the button on the USB hub, to enable the USB port.
At this point, the USB Meter reads 5.21V @ 0.00A.
I then turn off the printer's power supply, and the USB Meter reads 5.18V @ 0.11A
If I turn off the USB port using the switch, wait a few seconds, and then turn back on, the GT2560 turns on and the USB meter shows 5.18V at 0.11A.

If I turn off the USB port, wait several minutes, then turn the USB port back on, I will see the voltage drop and the current spike to over 1A, before it settles in around 5.15V @ 0.22A, and the GT2560 does not power on.

So, it seems that there is a high influx current, that the USB port and/or USB powered hub cannot satisfy.

I am just trying to learn what is 'normal' for this. If the GT2560 should power up with just USB power, or if I need to get it started using the printer power supply, then switch off to maintain USB power.

If the GT2560 is defective in some manner, I'll look at replacing it. If it is just the way it works, and I'm not risking damaging anything (like the poly fuses or the Mega2560) then that is fine.

Thanks!
-Al

[Mark]

Actually I always turn on the printer and then plug in the USB, or the other way around, seems no much difference. As long as the USB wroks then I think it won't be a problem.