T12 clones and grounding.

[tangelo]

Hello everyone.

I'm coming back to soldering after ~25 year hiatus. (Did some DIY kits as a hobby when I was a kid. So basicly I'm still a semi-complete noob at this)

I'm looking to buy a T12 clone from china. Most likely a Quicko Mini T12-942, Mini T12-943 or Full size T12-952.

https://www.aliexpress.com/item/MINI-T12-OLED-soldering-station-electronic-welding-iron-2018-New-design-DC-Version-Portable-T12-Digital/32839523934.html
https://www.aliexpress.com/item/MINI-T12-943-OLED-STM32-1-3inch-Digital-display-soldering-station-With-DC24V3A-US-EU-power/32980325982.html
https://www.aliexpress.com/item/2017-STC-T12-Digital-Soldering-Iron-Station-Temperature-Controller-EU-Plug-Temperature-180-450-Degrees-T12/32803295956.html

If I go with the minis I need an external power supply for it and if going that route I will prolly get a 24V 3A brick from china.

https://www.banggood.com/Excellway-9-24V-3A-72W-ACDC-Adapter-Switching-Power-Supply-Regulated-Power-Adapter-Display-EU-p-1250656.html

It is my understanding that the full size 952 units that have a build in power supply are grounded while all of the mini versions are not. My question is, how important is the tip's grounding while doing DIY electronic kits and arduino stuff? I realize the grounding is important when working with sensitive parts like something you find on computer/phone mothearboards etc. but how important is it usually with electronic kits?

Would it be more worth while for me to get a full size 952 unit (that costs more) that can be grounded and will that even guarantee that the tip is grounded? How paranoid should I be with the tip's grounding in the first place as I see lots of irons that are not grounded in the first place?

Also, the only difference between 942 and 943 that I can see is that the 942 is STC and 943 is STM32. And I take it there is not much difference between them for my intended usage (no interest is custom firmware flashing etc)? So I should just get the one which is cheaper?
 
Any opinions and feedback is highly appreciated.

[floobydust]

It's very important to have a properly grounded soldering iron. Two reasons:

Reason one is safety ground so the tip/wand/enclosure does not become hazardous live if the power supply's insulation between primary-secondary fails. There is a risk with the cheap chinese power supplies having no safety approvals or certificates, and coming from the bowels of gaungdong that the insulation and spacings are dangerous.
A (certified) double-insulated rated power supply is not dangerous in this way, such as name brand laptop bricks. But this does not cover reason #2 for grounding the soldering iron.

Reason two is ESD or stray charge at the tip can discharge to whatever you are soldering to. Leakage currents from the power supply can put some potential at the tip/wand, compared to earth ground. This is very bad as even 10V can damage semiconductor junctions. The tip can float up to high potential say 60V due to the brick's internal Y-capacitance. Prove it by measuring ACV between jack barrel to earth ground with a multimeter.


Regarding grounding the KSGER and Quicko T12-clone soldering stations,
For the mains power supply (inside) units, the metal enclosure and rotary encoder body are not grounded.
The IEC power entry PE GND does have a (sometimes very thin) trace to DC(-), so the tip and controller are grounded, but not the metal case. I add a 18AWG wire from IEC GND to the chassis, solder it to the encoder tab as the encoder is bolted to the chassis. The encoder body needs a ground for ESD zaps.

For stations powered off a laptop brick, if it's a two-prong mains cord then you are in hell. You need to run a PE ground wire to the station. Clone manufacturers advise using an isolation transformer but that still is a problem, there can be stray leakage currents.

Another thread on grounding T12 stations:
https://www.eevblog.com/forum/reviews/how-to-get-rid-of-fluctuating-voltage-on-soldering-tip-(t12-clone-station)/

[exe]

Reason two is ESD or stray charge at the tip can discharge to whatever you are soldering to. Leakage currents from the power supply can put some potential at the tip/wand, compared to earth ground. This is very bad as even 10V can damage semiconductor junctions. The tip can float up to high potential say 60V due to the brick's internal Y-capacitance. Prove it by measuring ACV between jack barrel to earth ground with a multimeter.

The thing is, a proper ESD protection implies a 1M resistor to ground, not a direct connection to ground: https://en.wikipedia.org/wiki/Antistatic_device#Antistatic_wrist_strap . So, I wouldn't call tip grounding as a ESD measure. To me it's a safety measure, same as why oscilloscope ground is connected to earth (but I'm no expert).

I myself inclined to have an isolated tip, or, better, a tip with 1M resistance to ground. The reason is, if tip is grounded and the circuit is powered (or capacitors are still charged), it can do a bang. Although, I'd say a sudden bang is also a good reminded to switch off the circuit and discharge caps.

[floobydust]

Ideally a 1MEG resistor to earth-ground would be used, but it is not practical.
Leakage currents due to the SMPS Y-capacitor or pri-sec winding capacitance on a 50/60Hz power transformer would cause the tip to float up even with a 1MEG resistor.
Example 2,200pF Y-cap on 120V/60Hz is 0.074mA, 240V/50Hz is over 0.133mA. Across 1MEG/200pF still over 60VAC. The power supply would also have to be double-insulated safety rated.

I admit to soldering with power on and seeing a blue spark as I put on the solder. Ground fault between soldering iron and DC power supply. The circuit was 12V and resistors, lamps and so I didn't care but took me while to figure out what was going on.

[Coyote]

In my opinion a good solution would be the use of certified PSU, like Meanwell RPS-120-24. It has double insulation, medical approved. Then connecting the tip and earth with 1M resistor makes the station ESD safe.

[Vovk_Z]

I use my T12 without grounding. I had problems with ground connected before when worked in live circuits (which is not good I know). I almost don't have anything grounded on my working place so I can't touch a good ground. So it can't bite me much if there is an isolation problem. It is much easier to work in almost isolated working place with isolated devices, because protection ground always makes parasitic loops.
I don't say that it is good but it is as I do.

[Grossmeister]

In my opinion a good solution would be the use of certified PSU, like Meanwell RPS-120-24. It has double insulation, medical approved. Then connecting the tip and earth with 1M resistor makes the station ESD safe.

What do you think about EPS-120-24? They look identical except that medical approval.
I'm thinking of buying a mini version of T12 station and planning to connect it to an external PSU, which will be connected to an outlet w/o earth ground. I might be able to find an earth ground for the case and tip and connect to it via separate wire with a high Ohm resistor.

[Shock]

ANSI/ESD S13.1-2019 is the latest US standard for soldering/desoldering hand tools.
Haven't seen it but the last 2015 standard performance criteria was less than 2.0 ohms, 20mV and 10mA leakage current.

As far as I'm aware it's two separate things, equipment and tool safety/grounding and ESD safety and personal and bench ESD safety setup.

[floobydust]

For electrical safety, the soldering iron tip is to be earth-grounded. Exception to this is if the power supply is double-insulated (like a two-prong laptop brick) but these still have Y-caps and leakage current that will make their output have a potential, enough to damage IC's. If in doubt, just measure it, ACV between DC(-) and earth-ground.

Because the T12 clone power supplies are never tested or certified to any safety standard, I would never expect the pri-sec insulation to be safe. Are they double-insulated? How many layers of tape? We don't know, so I earth-ground the secondary.

[msat]

After deciding I wasn't yet ready to drop $300 on a Pace ADS200 station, I briefly considered the ubiquitous Ksegr and all the clones/derivatives (who knows what's what anymore) and then came across a similar direct drive unit from Bakon https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20210112160335&SearchText=bakon and found a teardown of it online. Other than using Chinese electrolytics, all the active components along with the MCU were name brand, and had a pretty well designed SMPS along with a grounded tip. I figured that there weren't a million clones of it (yet) and therefore would be a safer bet than a "Ksegr". I purchased mine from Amazon with an assortment of tips for ~$30. Performance is excellent, and not just "for the price". I highly recommend it.

Edit: Also, it was cheaper than the Ksegr & clones.

[Shock]

Though I've not seen any recent videos of the Bakon 950D, the Ksger T12 controllers do appear to be faster at heating.

There was a photo taken a while back showing a Bakon 950D T12 clone where the ground/earth prong was present on the smps mains plug, but inside the smps enclosure the wire was cut off and left two wire. I've not investigated grounding the tips on these models so unsure of problems that could arise from doing so.

So yeah, neither of them are perfect in my opinion.

[Grossmeister]

Well, in my case the idea of buying mini version is to move away from an unknown (and sometimes even random) embedded Chinese PSU and instead use external PSU from a reputable brand. I feel uncomfortable having 220V on my table inside of a cheap Chinese metal box.

About 950D: I read a review where author measured 19V at the output of stock PSU, which gave 42W output power with the tip included. So, yes, by default it is slow. He then modded that PSU for 23V.

[msat]

I also read about that mod. IIRC, it was the versions intended for the Americas which were around 40W, while other markets were getting ~60W.

I opened the enclosure when I got mine and found a fairly beefy ground wire being used and certainly connected. That's unfortunate that that's not always the case.

@Grossmeister
You bring up a good point about using an external SMPS from a reputable manufacturer. On laptop chargers that are grounded, is one of the outputs on the DC side generally tied to ground?

[Grossmeister]

I don't have a laptop PSU with ground. Also, EPS-120 specification shows only to input AC pins: neutral and line, no ground. They also mention that grounding is required, although I don't understand what do they mean: grounding the PSU or device connected to it?

[rstofer]

Why fool around?  It will be difficult to come in much cheaper than the Hakko FX888D and that iron is known to perform.

https://www.amazon.com/Hakko-FX888-23BY-Soldering-Station-T18-B/dp/B00C4UEBRM

The iron by itself is a few bucks cheaper but there is value added with this kit.

[rstofer]

I don't have a laptop PSU with ground. Also, EPS-120 specification shows only to input AC pins: neutral and line, no ground. They also mention that grounding is required, although I don't understand what do they mean: grounding the PSU or device connected to it?

In the end, it comes down to safety codes.  There are exceptions for double-insulated tools but, generally, all non-current carrying metallic surfaces are to be grounded.  That's why the BNC connectors on scopes are all earth grounded.  This causes no end of concern when probing but it's a safety thing.

Now, can a soldering station be double-insulated?  Probably.  But if you look at the Hakko FX888D, there is a 3 wire power cord to provide earth ground.

https://www.amazon.com/Hakko-FX888-23BY-Soldering-Station-T18-B/dp/B00C4UEBRM

[msat]

While I'd agree that the Hakko is a safe bet, we're still not exactly comparing apples to apples. For one, some of these irons we're talking about are roughly 1/3 the price. Also, we're talking about direct drive T12 clones, rather than the T18 of the FX888. Using a direct drive iron changed my [soldering] life!

That said, the Hakko probably would stand the test of time. We had several chinese soldering stations at my old makerspace, and they all died. Despite that, other than the chinese electrolytics and T12 clone tips in my Bakon, I think it might hold up well.

[Shock]

Speaking of clones, the ultimate clone the Unisolder 5.2+ can be seen here running the Pace TD200 handpiece with 4-5s to reach 300C/570F.

[Sunnysunsun]

Sorry, old thread but I’m not sure how I should ground my quicko 955’s tip. There’s a trace in the pcb originating from from the earth prong but it isn’t connected to anything. There’s no continuity between the plug or either one of the DC wires leading from the power supply to the STM32 board.








I have two questions:

1. Should I connect just the iron tip to earth and remove this 0ohm resistor or should I keep the 0ohm resistor and connect both the tip and the (-) of the STM32 board to earth?

2. Should I ground my tip directly by soldering a wire from between the two boards or should I attach a 1M ohm resistor in series like an earlier poster recommended? My old iron has a direct near 0 ohm resistance between the iron tip and the earth prong of the AC plug so I think that’s what I’ll ground this iron as well?

[Jesus]

Hello everybody, I recently got a unisolder kit online. Is the rps-120-24 a good choice to power it up?

[Edcali]

Hi, What did you ended up doing to your station? Did you Grounded Soldering a wire to Ground to Ground? or did you use a 1Mohm resistor? or Did you keep it without any mod?