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Dangerous Solder Station KSGER T12

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DangerZone:
Hello EEVBLOG Community

Got something Interesting:
Today I had unpacked my KSGER T12 Solder Station and went right into Soldering.
My ESD matt and strap was also brand new.
As I was Soldering my strap felt extemly uncomfortable because it bit me very hard.
First I thought that the Material was not good, but while I was soldering LEDs, they began to produce light.
Then I measured the Voltage from the Solder Iron tip to my ESD matt and measured 73V AC and directly to Ground 80V AC  :palm:
So yeah the weird bitting was because it always shocked me a little bit.
All my effort to protect my Circuit from ESD was for the Cats  |O

Then I sent those Results to my Friend (which has a Brand ersa solder station at his company) and he said he also noticed that when he was Soldering that the LEDs sometimes light up!
He measured 15V AC to the matt and 40V AC directly to Ground.

Without further investigation (maybe I will do it when I have time), how is this possible (how could the Solder Iron have 80V AC on the Tip)?
Doesn't that mean, that my Solder Iron isn't galvanically Isolated?
Does anybody also have noticed such a problem (because also one of the Brand ersa seemed to have no galvanic isolation)?
Should it not be a standart to Ground the Soldering Tip, or are there applications when you don't wanna have this?

AVGresponding:
It could be galvanically isolated, but AC-coupled via suppression capacitors. If the earth connection from the unit to the wall outlet is faulty, then the path to earth for this leakage current becomes you and your ESD strap and mat...

Looking at the internal construction of this unit, it looks like the mains connections could easily become open, due to mechanical stress from inserting and removing the power lead.

BrokenYugo:
It is indeed standard to use a 3 wire cord and tie the tip directly to the earth wire, both to shunt any mains leakage current (what you're feeling, hopefully) and prevent any static buildup.

Open the unit up and have a look around, this cheap Chinese stuff should really be treated as a kit and inspected before power up, sloppy work with the grounding is typical, along with the occasional more hazardous mistakes in design or assembly.

DangerZone:
yes indeed, I opened it up, and it hasn't even the aluminium case grounded, also main powerlines running underneath the heat sink with just the solder paste as isolation.
I also broken the thing trying to fix all issues, now the heat regulation isn't working anymore and it gets glowing hot.
What a waste of time and money.
Never buy something again from china  :palm:

floobydust:
KSGER did change their power supply's PC board grounding.

Soldering Power V2.04 (green pcb) has mains PE ground from IEC connecting to the 24VDC secondary side GND, so the controller board and heating-element is grounded. The enclosure is not.
Safety mod is add a ground wire to the case, that also covers ESD to the knob/encoder. The heatsink over the HV PCB trace, add some insulating tape or lift the heatsink.

Soldering Power V2.05 (black pcb) has mains PE ground from IEC connecting to a large pad and open jumper/pin3 DC output connector, to the 24VDC secondary side GND, so the controller board and heating-element is NOT grounded and floats up to HV due to the Y-cap  :palm:  The enclosure is not grounded either. They fixed the HV trace spacing bug in older V2.04
Safety mod is to connect jumper, and add a ground wire to the case, it also covers ESD to the knob/encoder.

If you want your soldering iron isolated/floating and trust the "double insulation" of the power transformer etc. instead of the hard grounding, use a 1MEG resistor from PE to DC GND. Just measure continuity, and then ACV when it's running to confirm the tip is not floating up to something that can damage semiconductors or people.

edit: updated the KSGER PSU schematics and posting here:
https://www.eevblog.com/forum/reviews/t12-stm32-v2-1s-soldering-station-controller-schematic-etc/msg2467236/#msg2467236

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