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LCD panel flashing when off  

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woodificould
(@woodificould)
Eminent Member
LCD panel flashing when off

I just finished building an MK2S kit. When I was done, with the power cord still unplugged, I slid the bed forward and back on the Y axis to ensure everything was clearing. I noticed that the LCD panel flashes on. It seems like the Y axis motor is generating electricity, which is flowing back into the board and actually providing enough power to light the display panel. Is that normal?

Posted : 25/01/2018 7:25 pm
Neal
 Neal
(@neal)
Reputable Member
Re: LCD panel flashing when off

When a motor is turned by hand it generates electricity. Not much difference between an electric motor or a generator. Be careful. While not common it can sometimes back feed power through the electronics and cause problems. Just move it slower in the future.

Neal

Posted : 25/01/2018 7:45 pm
woodificould
(@woodificould)
Eminent Member
Topic starter answered:
Re: LCD panel flashing when off

Yes, I understand that. I guess I was expecting there to be protection diodes in there somewhere to prevent current from flowing back into the non-motor circuits. My main concern was that I wired this thing correctly, so by asking if it is "normal" behavior, I meant does this actually happen on other MK2S printers? Should I infer yes from your answer?

Posted : 25/01/2018 8:25 pm
Neal
 Neal
(@neal)
Reputable Member
Re: LCD panel flashing when off

Yes it happens to everybody at one time or another.

Neal

Posted : 25/01/2018 8:26 pm
woodificould
(@woodificould)
Eminent Member
Topic starter answered:
Re: LCD panel flashing when off

Cool. Thanks.

Posted : 25/01/2018 11:33 pm
digibluh
(@digibluh)
Reputable Member
Re: LCD panel flashing when off


Yes, I understand that. I guess I was expecting there to be protection diodes in there somewhere to prevent current from flowing back into the non-motor circuits. My main concern was that I wired this thing correctly, so by asking if it is "normal" behavior, I meant does this actually happen on other MK2S printers? Should I infer yes from your answer?

i've had a few different boards and stepper drivers... they all do it.... sometimes a fan might spin too.

Posted : 28/01/2018 8:27 am
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