1 Topic by ITman496

  • ITman496
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Topic: some odd phantom power phenomenon

The other day after I shut the printer (my SD2) down after a good day of printing, I noticed it was still making some noise.  Strange, as the 12v power pack was 'unplugged' (I have it plugged into a distribution switch box thing, each outlet is on a button, it definitely had no power, LED lights were off, etc.

So it was still making a bit of noise, I open the front door and the fans are still spinning! Slowly, but still spinning.  I was waiting for them to spool down, they weren't.  Eventually I stuck my finger on one to stop it, and it started back up soon after. 

So it appears that when 12v power is removed, 5v from the USB connector leaks into the 12v bus.

But then I tried to replicate it today, didn't work.

So how can it intermittently leak into the 12v rail?  I hope it doesn't leak in the other direction..

2 Reply by Redbeer

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Re: some odd phantom power phenomenon

Another interesting and potentially related phenomenon.

I have a powerline adapter for the computer that I run the Solidoodle 4 from.
When the Solidoodle is powerd up, it interrupts/interferes with the data signal to the two computers on that powerline adapter.
As soon as I shut the Solidoodle down, the problem goes away and full internet access comes back.

Definitely something strange with the power system.

3 Reply by elmoret

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Re: some odd phantom power phenomenon

ITman496 wrote:

The other day after I shut the printer (my SD2) down after a good day of printing, I noticed it was still making some noise.  Strange, as the 12v power pack was 'unplugged' (I have it plugged into a distribution switch box thing, each outlet is on a button, it definitely had no power, LED lights were off, etc.

So it was still making a bit of noise, I open the front door and the fans are still spinning! Slowly, but still spinning.  I was waiting for them to spool down, they weren't.  Eventually I stuck my finger on one to stop it, and it started back up soon after. 

So it appears that when 12v power is removed, 5v from the USB connector leaks into the 12v bus.

But then I tried to replicate it today, didn't work.

So how can it intermittently leak into the 12v rail?  I hope it doesn't leak in the other direction..

It's backfeeding through the LM7805 onboard. Cheap design, but won't hurt anything.

Filastruder - the robust, inexpensive filament extruder
E3Dv6 All Metal Hotend - the premier 3D printing hotend

4 Reply by ITman496

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Re: some odd phantom power phenomenon

Oh okay. I didn't realize it's regulator could backfeed.

5 Reply by bootdsc

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Re: some odd phantom power phenomenon

I have been wondering about the same thing and just found your post. This information should be a official sticky, it's certainly a design flaw having to unplug power and usb to get everything to fully shutdown and i have noticed the controller board gets excessively hot when left running off usb.

6 Reply by solijohn

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Re: some odd phantom power phenomenon

elmoret wrote:
ITman496 wrote:

The other day after I shut the printer (my SD2) down after a good day of printing, I noticed it was still making some noise.  Strange, as the 12v power pack was 'unplugged' (I have it plugged into a distribution switch box thing, each outlet is on a button, it definitely had no power, LED lights were off, etc.

So it was still making a bit of noise, I open the front door and the fans are still spinning! Slowly, but still spinning.  I was waiting for them to spool down, they weren't.  Eventually I stuck my finger on one to stop it, and it started back up soon after. 

So it appears that when 12v power is removed, 5v from the USB connector leaks into the 12v bus.

But then I tried to replicate it today, didn't work.

So how can it intermittently leak into the 12v rail?  I hope it doesn't leak in the other direction..

It's backfeeding through the LM7805 onboard. Cheap design, but won't hurt anything.

I would recommend that you always unplug the Solidoodle from your computer when shutting it down for the night. Backfeeding shouldn't be problem, but it pays to be cautious.

Former Solidoodle employee, no longer associated with the company.

7 Reply by Antron007

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Re: some odd phantom power phenomenon

I've always unplugged both. I just thought that that was how it worked. I figured it was usb powering the board and the power supply was for the heater and motors.