T12 Soldering Iron Clone Kit

[don.r]

Just received my AliExpress KSGER T12 soldering iron clone kit. Has anyone else built this kit? I may post some pictures up if there is interest. I noticed already that the PE connection has no Y caps to N or L and that it basically stops at the PSU input (case is plastic). The PE connection on the iron is just NC (although I haven't confirmed with continuity yet, it looks most likely that it is not connected).

[pigrew]

I have a similar unit (pre-assembled). I just verified that it doesn't have a good ground connection. They tried at grounding the aluminum case, but paint on the case prevented an electrical connection.

I'll edit this post later and add photos of my unit.

Don.l, perhaps you could post photos of your kit?

EDIT: Photos added of pre-assembled kit (with modifications: Extra ground wire to the iron connector's shell, and ground off the coating from the case in order to allow electrical contact)

[don.r]

PSU shows no Y caps on inputs and ground connection ends at input where its connected to the plastic case. Front panel board has a ground connection going to the tip but is unconnected at the board. 

[pigrew]

I added photos to my previous post. My board is a "F Wxk T12-D". It's correct that there is only an X cap and no Y caps. The power-board GND terminal isn't connected. There's an extra wire going from the power-input's GND to the controller PCB's COM. Through that connection, the tip is earthed. I added an extra wire to ground the shell of the connector. The unit has a sheet of plastic insulator at the top of the case (prevents shorts if the power supply becomes loose in the unit?).

The COM/GND connection on the controller PCB is just a solder-blob. There were not enough pads for all of the COM wires so they just solder-blobed it together. Even still, I measure less than 1 ohm (approx 0.95?) from the end of my power cord to the soldering iron tip.

My unit has just a basic power-connector on the back, though I've seen photos of a "T12-A" model with an integrated power-inlet that has a fuse.

Also, the ring-connector at the back of the unit was soldered together (I think that it's supposed to be crimped?). There was so much paint/annodization that there was no contact to the aluminum case. I ground off the coating so that my case now has a good ground connection.

Overall, the soldering iron works well enough, though the OLED display is quite dim through the plastic front-panel. I may 3D-print a new front-cover with a simple cutout for the display.

[stj]

unless it uses a 3core cable with earth on it, you dont want Y caps because it will make your iron live at 50% of line voltage!

[pigrew]

unless it uses a 3core cable with earth on it, you dont want Y caps because it will make your iron live at 50% of line voltage!

The unit comes with a 3-conductor power port (IEC C6 Mickey-Mouse type). Since I got mine on Taobao, it came with a Chinese-style plug.

Perhaps they assumed that the grounds would not be wired properly, so they didn't want to provide the Y capacitor? However, I would imagine that the parasitic capacitance in the transformer may create the same effect to some extent.

The power-supply does have a position to install the Y-capacitors, they just didn't load them. Though, they share a pad with the fuse, so I'm not sure that both a fuse and pair of Y-caps could be installed simultaneously.

[don.r]

I just installed a pair of Y caps under the board. Just to be clear, there is already an existing Y cap going from secondary negative to primary neutral. I really like the PSU actually. Lots of good clearances, spark gaps on the board and parts where they need to be (apart from the missing Y caps which is not a big deal) like a dual input choke, an NTC thermistor inrush limiter and an X cap on the input. Lots of filtering including a coil on the output. Ripple seems very low. The proximity of the caps next to the heatsinks isn't the best. My IEC has an integral fuse and switch.

The lack of PE to the iron tip is just stupid. I added a wire from earth on the PSU input to the tip E wire (green wire). The fit and finish on the plastic case is a joke, stick to the metal case for a few dollars more.

Mounting the iron socket to the front panel is proving to be a challenge as they soldered the connector on and its too big to fit through the opening and to take the mounting nut and washer off. At any rate the mounting hole is too small for the socket anyway. Dremel time. The knob is also too tall and when the board is rotary encoder is mounted, the push button no longer works because the knob stops at the face plate. Minor niggles but still irritating.

[pigrew]

I just installed a pair of Y caps under the board. I really like the PSU actually. Lots of good clearances and parts where they need to be (apart from the missing Y caps which is not a big deal). A dual input choke and an X cap on the input. Lots of filtering including a coil on the output. Ripple seems very low. The proximity of the caps next to the heatsinks isn't the best.

The lack of PE to the iron tip is just stupid. I added a wire from earth on the PSU input to the tip E wire (green wire). The fit and finish on the plastic case is a joke, stick to the metal case for a few dollars more.

Mounting the iron socket to the front panel is proving to be a challenge as they soldered the connector on and its too big to fit through the opening and to take the mounting nut and washer off. At any rate the mounting hole is too small for the socket anyway. Dremel time. The knob is also too tall and when the board is rotary encoder is mounted, the push button no longer works because the knob stops at the face plate. Minor niggles but still irritating.

How do you choose the value of the Y capacitor?

I might not add them since I don't want to deal with digging all the potting compound off of the board. I'll definitely design a new front panel. I have the version without the two LEDs. I think the new "T12-A" boards have the extra power light. I wish the firmware would allow brightness adjustment, but mine doesn't (at least in English; I didn't check the Chinese menus....).

[don.r]

Since they are on the inputs before the choke its not too critical and only to suppress noise. I had some 220nf 400V ones kicking about so I used those. They properly need to be after the choke but meh...

[don.r]

Kit is now all together and works fine. Plastic case has really poor fitting of boards. Had to snip off a corner of the front panel circuit board to make things fit. Bottom line, stick to the metal case. Other than that the iron works great. Heats really quickly. Temp comes in at about 20C below reading but I probably have to run the tip in for a few minutes to get a more accurate reading. Iron goes to sleep (200C) and wakes up with a shake. Its 300C in about 5-10 seconds.

Good:    - PSU
             - Iron itself
             - Price (I paid about US$40 delivered, kit + 4 tips, no power cord)

Bad:      - Tip grounding. Tip earth and negative are connected on the front panel board but with no ground connection to PE, this is pointless. Clearly they designed this with a metal case in mind so that the rotary encoder would ground everything.
             - Case fit/finish and plastic quality.
             - Pre-wiring of pencil socket makes assembly more difficult.
             - Rotary encoder knob too deep.

tl;dr: decent product but get the metal case version.

[kt315]

I was looking at this kit at some point as well. The thing that left me really puzzled is that all those listings show 220v as input. Does the power supply work with 120v or is it a different kit? If so, can you send the link.

[pigrew]

I was looking at this kit at some point as well. The thing that left me really puzzled is that all those listings show 220v as input. Does the power supply work with 120v or is it a different kit? If so, can you send the link.

The one I have (prebuilt and purchased in China) works fine with 120V. These all use switching supplies that will adapt to the full range of input voltages.

Worst case, you'll need a larger amperage fuse (120V will use more current than 220), but mine came with a plenty high rated fuse (soldered to the board, of unknown amperage).

[ciccio]

I built a similar kit, bought on Banggood.
I did not include a power supply, so I got one from Banggood.
The supplied palstic case was too small, so i put everything inside an Hammond case I had on a shelf.
The soldering iron works very well, but if I wire the the tip's ground pin  to PE (and the case) the display become unstable.
The instruction provided are not up-to-date: they show two wires for powering the board, but in effect there are three wires: red (positive) black (negative) and a green one that is connected to tip ground pin.
I presume this is intended for tip grounding.
In any case if I ground the tip I have an unstable display.
I tested again with my bench DC power supply, thus replacing the Chines board, but it is still unstable.
I see that the OP reports that TIP and negative are connected on the main PCB. It is not my case, they are separated.
If I connect them togheter, the display is unstable.
For now I have no time for further testing, and I'll keep the station with ungrounded tip...

[Chris56000]

Hi!

Is/was the T12 an O.S.H.W. project with documentation/gerbers available, and can you get blank PCBs, or have the Chinese made them so cheap it's not worthwhile to "roll your own?"

Chris Williams

[stj]

there are many T12 projects / controllers.

the best are open-source.
th TS100 and this:
http://dangerousprototypes.com/forum/viewtopic.php?f=56&t=7218&p=61175#p61175

[sn4k3]

there are many T12 projects / controllers.

the best are open-source.
th TS100 and this:
http://dangerousprototypes.com/forum/viewtopic.php?f=56&t=7218&p=61175#p61175

+1 for that opensource station. but BOM is hard and not so cheap

[sn4k3]

I built a similar kit, bought on Banggood.
I did not include a power supply, so I got one from Banggood.
The supplied palstic case was too small, so i put everything inside an Hammond case I had on a shelf.
The soldering iron works very well, but if I wire the the tip's ground pin  to PE (and the case) the display become unstable.
The instruction provided are not up-to-date: they show two wires for powering the board, but in effect there are three wires: red (positive) black (negative) and a green one that is connected to tip ground pin.
I presume this is intended for tip grounding.
In any case if I ground the tip I have an unstable display.
I tested again with my bench DC power supply, thus replacing the Chines board, but it is still unstable.
I see that the OP reports that TIP and negative are connected on the main PCB. It is not my case, they are separated.
If I connect them togheter, the display is unstable.
For now I have no time for further testing, and I'll keep the station with ungrounded tip...

Recently i got a kit that does same thing as you and i think we are using same kit STC 2017.
But if i use a external DC adaptor it work well.
My tests are:

Green -> AC Earth (Unstable Display)
Green -> AC Earth + GND (Stable, but temperatures not good if set more than 350ºc, ex: 400ºc turn in 360ºc real)
Green -> External Adaptor GND (Stable, temperatures seens to work a bit better, but not in the point)

Tomorrow i will test more
Heres my connections:



I also test for amp consumption. Just 2.5A max at 24v... should be 3A if we follow the specs

[sn4k3]

I was able to fix the problem, in my case the default wires are not good enough...
I used thick wire for AC and 20AWG to DC connections, get away from 3 pin header and all other headers and solder directly to the boards.
It fixed all problems, unstable LCD was from wires and connections.

I shorted Earth to GND, all good now and temp go up to 450ºc. Before just 360ºC-380ºC max

[stj]

so the element caused volt-drop?
interesting - that could cause problems over time in other similar units if the connectors start warming up!

[sn4k3]

so the element caused volt-drop?
interesting - that could cause problems over time in other similar units if the connectors start warming up!

Probably but there are other factors too, provided cables can be enough for 24V and 3A it looks to me a AWG24. But i suggest to replace it anyway to a better and thick cable like AWG22 or AWG20 for a lower resistence and use quality ones. I also replace because i need more length.
For AC i used a pure cooper thick cable, maybe AWG18, may be overkill but it also have good isolation.

The main problem is the XH2.54 connector, it seens a bit loose, and renember they don't solder wire to clips, they smash wire against the clip, so is a bad connection all the time. Get rid of it and directly solder everything like me 

[stj]

2.54mm pitch connectors are not suitable for high current, they should have used 3.96mm stuff.

[sn4k3]

2.54mm pitch connectors are not suitable for high current, they should have used 3.96mm stuff.

Yeah, but the problem would continue even if they use bigger terminals, the copper wire smashed against the clip is not a good conductor.
I will post a image latter

[sn4k3]

My setup:














Last image is provided cables for connectors

[ciccio]

Thanks sn4k3: I follower your advice (partly) and the station  works really better.
I actually soldered two pieces of 0.75 mm2 wire, one to the + and the other to earth an minus pads (shorted)  of the board connector (as per your photo), and kept the original 3 thin wires, two (red + black)  in parallel to the new ones, wired to the power supply and one (green) to metal case and PE.
Now the display is stable up to more than 400 °C.
I also shorted the negative and earth pads inside the handpiece, to get a lower resistance (-25%) of the wiring to the heater.

Maybe the circuit tracks to the handpiece connector are too thin, but I do not want to disassemble the board for checking, and eventually solder thick wires over those tracks...

[sn4k3]

Thanks sn4k3: I follower your advice (partly) and the station  works really better.
I actually soldered two pieces of 0.75 mm2 wire, one to the + and the other to earth an minus pads (shorted)  of the board connector (as per your photo), and kept the original 3 thin wires, two (red + black)  in parallel to the new ones, wired to the power supply and one (green) to metal case and PE.
Now the display is stable up to more than 400 °C.
I also shorted the negative and earth pads inside the handpiece, to get a lower resistance (-25%) of the wiring to the heater.

Maybe the circuit tracks to the handpiece connector are too thin, but I do not want to disassemble the board for checking, and eventually solder thick wires over those tracks...

I'm glad to help 
If you want futher improve you need a better cable to the handpiece, the cables are to thin, but if you go thicker cable will be heavy and bulky.
I think PCB is OK, they may develop that to meet the specs, even provided cables are thicker than handpiece cores, and they are ok to support the current, you just need to direct solder and get rid of connectors which you already done. Now the bottleneck is on handpiece cable.
I don't have a proper metter to test the cable under stress and it resistance but i suspect the results will not be that good

But with all that improvements i think it's already good, stable temperature up to 400ºc. Fast recovery. Don't need more than that anyway. Also the price we pay for these things are a bless

EDIT: I will get detailed picture of control board and post for track inspection