Beware of the PinePower Desktop supply

[Traceless]

A while ago I aquired a PineCil Soledring iron, which is very similar to the TIS-100 and along with it a PinePower desktop power supply. Most of the time I use my bigger soldering station but I ordered the Pinecil with some smaller tips for the finer work. Today I was trying to solder integrated power stages to a graphics card which were closely surrounded by 0603 and 0402 smd components. I took out the Pinecil and hooked it up to the Pinepower 65W USB-power delivery port. Once I started soldering the iron randomly cut out and rebooted. Initially I expected a problem with the USB cable or maybe a broken port but couldnt find any mechanical issues. Then I suspected some contact issue with the tip but likewise I could not find any issue there. So I started to look into the issue electrically and-sure enough the iron carried 20V DC AC in the tip, touching a ground reference causes the iron to reboot. The culprit is actually the pine desktop powersupply. For some odd reason the USB-C port outer shield carries 20V.

I'm not sure if this is a design flaw or if I got a defective unit but if you have this supply better check the USB-PD port before using it (and destroying expensive stuff in the process by injecting 20V into sensitive circuits).

[thm_w]

The outer shield carries 20V with respect to earth ground? Not with respect to USB ground right?

Its normal for USB power supplies to be floating, and therefor needing a dedicated ground lead when used with soldering irons. They will often have some voltage on them due to AC filtering capacitors used, but usually AC voltage at low currents (http://www.aplomb.nl/SMPS_leakage/Doc_ie.html).

This PinePower unit does have a 3 pin power cable, so you'd think they'd earth the USB shield.. hm

If you want to make the iron ESD safe you can connect the shield back to earth ground inside or outside of that PinePower. But. You might want to open up the PinePower and take some photos first just to get an idea of what they are doing.

[Traceless]

The outer shield carries 20V with respect to earth ground? Not with respect to USB ground right?

Yes the graphics card was placed on a grounded metal rack on top a my preheater.

Its normal for USB power supplies to be floating, and therefor needing a dedicated ground lead when used with soldering irons. They will often have some voltage on them due to AC filtering capacitors used, but usually AC voltage at low currents (http://www.aplomb.nl/SMPS_leakage/Doc_ie.html).

Okay, but even if the current is low soldering the output side of an 1.1V GPU powerstage with an iron tip carrying 20V is probably not healthy for the chip.

This PinePower unit does have a 3 pin power cable, so you'd think they'd earth the USB shield.. hm

If you want to make the iron ESD safe you can connect the shield back to earth ground inside or outside of that PinePower. But. You might want to open up the PinePower and take some photos first just to get an idea of what they are doing.

My PinePower unit actually has a two pin Euro Plug (IEC 60320 C7) so it is not connected to mains earth.

[thm_w]

Okay, but even if the current is low soldering the output side of an 1.1V GPU powerstage with an iron tip carrying 20V is probably not healthy for the chip.

Yeah its not great, any proper ESD safe iron will have the tip earthed.

My PinePower unit actually has a two pin Euro Plug (IEC 60320 C7) so it is not connected to mains earth.

ahh interesting.
If you have a spare mains cable, you can make an earth lead that goes from your power bar then connects somewhere on the PinePower or Pinecil, that will make its way to the tip.
Another option is trying to swap out that 2 pin for a 3 pin.

[Traceless]

Okay, but even if the current is low soldering the output side of an 1.1V GPU powerstage with an iron tip carrying 20V is probably not healthy for the chip.

Yeah its not great, any proper ESD safe iron will have the tip earthed.

My PinePower unit actually has a two pin Euro Plug (IEC 60320 C7) so it is not connected to mains earth.

ahh interesting.
If you have a spare mains cable, you can make an earth lead that goes from your power bar then connects somewhere on the PinePower or Pinecil, that will make its way to the tip.
Another option is trying to swap out that 2 pin for a 3 pin.

The Pinecil actually has a screw terminal for a dediated ground lead but running another wire is a bit of a hassle. Currently I'm thinking about just buying a Lenovo charger to power the iron - that should solve the issue without running a dedicated ground wire to the iron.

Still I think it is pretty bad design by Pine, I'm probably not the only one using the PinePower as PSU for the Pinecil.

[thm_w]

Yes running to iron is a hassle, which is why I'd rather run it to the power supply ground. I assume Lenovo adapter is earthed, no guarantee.

Their official stance is going to be "if you want it grounded use the grounding tab on the iron". I get that no one does, but consequences are still on the end user.

[Traceless]

I tested the Pinecil soldering iron today with a Lenovo 65W USB-C charger. No problems the USB-C Port is properly grounded and so is the soldering iron tip.

I also recorded a short video of the PinePower acting up. In the clip you can see how there is ~20V AC on the USB-C plug outer shield. The soldering Iron turns on when connected to the USB-C port but since there the tip is "grounded" via the USB-C lead the tip becomes live with ~20V AC. Interestingly the AC-Frequency changes when the iron is connected compared to measuring from the USB-C lead directly. I'm not sure but I assume that might be related to the PinePower switching output mode because the iron negotatiates 20V (the pine power's display shows the negotiated output voltage once the iron is connected. Does anybody have a theory what is going on here?

Video Clip: PinePower USB-C port outputting 20 V AC

[thm_w]

Take the negative lead of your multimeter and connect it to earth ground. Having it floating in the air is going to depend on coupling to your body, etc.

[Traceless]

Take the negative lead of your multimeter and connect it to earth ground. Having it floating in the air is going to depend on coupling to your body, etc.

With the negative lead connected to earth ground I get a reading of ~100V AC at frequencies between 700 and 1200 Hz

[coppercone2]

I almost want to put an earth ground lug on a DMM front panel to make this test easy

[Traceless]

Here is a short recording of the repeated measurement against mains earth.

[MathWizard]

In the winter I get a lot of static shocks picking up my iron, it's grounded for sure. Even the cord is relatively conductive to static discharge