Quecoo T12-958 soldering station - INVER error?

[spleenharvester]

I bought a T12-958 recently with an M8 handle and until now it has worked very well. The tip wasn't earthed but that was easily resolved.

Now, whenever it is switched on, it heats up to about 70*C then shows an [INVER] error on the screen and stops. In order to fix it I have to either unplug and re-plug the handle, or unplug and re-insert the tip from the handle. While doing that it changes to [ERROR], then it finishes heating up and works perfectly. Until it's turned off, after which it will show [INVER] again next time it is turned on.

Any idea what the problem is?

[stj]

do you have any more cartridges?
also, on some early irons people had to open the handle and bend the spring contacts
you can inspect the soldering on it too

[spleenharvester]

do you have any more cartridges?
also, on some early irons people had to open the handle and bend the spring contacts
you can inspect the soldering on it too

Yip, same thing happens with a new cartridge.

Soldering looks good at both the connector and in the handle, doesn't look like anything is shorting. Contacts within handle have been bent and it still does it. I don't think this one is a connection issue as if you keep the iron in exactly the same place without touching it the problem is reproduceable.

It seems to be something about that 70-80*C point that trips the error. Every time it heats up to that point it triggers [INVER]. If you restart the station while the handle is above 80*C it will heat up no problem. If you restart the station and let the handle cool to <80*C first it triggers the error. Very odd. Would help if I knew what the heck that error means. I wonder if the motion sensor in the handle has failed or something?

EDIT - OK a bit more info - the error is actually [INVERT] and it only seems to happen on DC24V, it's fine on AC. Happens with multiple DC24V supplies that support >4A. I've been pouring through the custom T12 firmware project files and can't find any reference to this error.

Side Q - should I have put a 100K resistor from tip to earth? I bridged the tip earth pin to the mains earth pin as it was unearthed but I've just seen a schematic that seems to put 100K between?

[stj]

the resistor/link really depends on your work and if your supervised by a rule following scumbag.
legally it's supposed to be earthed, the resistor may count but i'm not sure.
if it is then you cant work on live circuits or big charged capacitors though.
i use a resistor on mine but it's bigger than 100k from memory.

getting back to the fault, interesting - can you try with the dc supply and meter the voltage at the pcb as it heats up?
maybe the voltage is dropping because a cable or other part is under-rated

[spleenharvester]

the resistor/link really depends on your work and if your supervised by a rule following scumbag.
legally it's supposed to be earthed, the resistor may count but i'm not sure.
if it is then you cant work on live circuits or big charged capacitors though.
i use a resistor on mine but it's bigger than 100k from memory.

getting back to the fault, interesting - can you try with the dc supply and meter the voltage at the pcb as it heats up?
maybe the voltage is dropping because a cable or other part is under-rated

I've done some more playing around and can confirm reproduceably it only happens on DC, and only happens once the iron starts from cold. If the iron is already >100*C, it doesn't cause the error. So I think that reasonably rules out the handle.

This is really perplexing me - the DC voltage on my current power supply (an Einhell 4Ah tool battery) is stable at +20.8V during warm-up and when the error occurs. The voltage on AC is +25.2V. According to the AliExpress listing the acceptable range is 19V to 24V so this difference can't be causing my problem surely? And this battery can output something like 25A CDR so I can't imagine current is a problem.

Quecoo replied saying 'there is a shrapnel [sic] that needs tightening with pliers in the handle', whatever that means. But they seem to be wrong as the handle is fine on AC.

(As an aside - some more poking around, I've found the green earth wire Quecoo added between the PSU and the controller board doesn't actually connect to anything lol it's just a lone pad on the controller board side)

[spleenharvester]

OK I tried another power supply, this time an Asus ROG AC adapter that outputs DC20.4V. Worked perfectly. So seemingly it does not like the tool battery, any ideas why? (It does still work perfectly after unplugging and re-plugging the tip to clear the error?)

[redwire]

Just add a 1MEG pullup at the GX12 pin 5/heater/thermocouple input, to power +24V. It ends up being across the mosfet D-S. This stops the spazzing and freaking out, an open cartridge will now give a stable OPEN error message instead of picking up hum and noise. This is also aggravated by how noisy your PSU is. Your battery does float from PE ground so hum and noise pickup at the tip will be greater. Or add more bulk capacitance to the 24V rail, some controller boards are really cheap and have no 100uF cap there.

The tips have bad connections inside, new ones they sometimes need to be cooked it can sorta work. I think it's just dirty spot welds inside the white caps or in the maybe in the heating element, but using it seems to eventually fix the bad connection.
Some cartridges I have taken apart (caps) and tried to solder that bad connection to stop the drama.

There are also lots of other fixes to T12 quirks.

[spleenharvester]

Just add a 1MEG pullup at the GX12 pin 5/heater/thermocouple input, to power +24V. It ends up being across the mosfet D-S. This stops the spazzing and freaking out, an open cartridge will now give a stable OPEN error message instead of picking up hum and noise. This is also aggravated by how noisy your PSU is. Your battery does float from PE ground so hum and noise pickup at the tip will be greater. Or add more bulk capacitance to the 24V rail, some controller boards are really cheap and have no 100uF cap there.

The tips have bad connections inside, new ones they sometimes need to be cooked it can sorta work. I think it's just dirty spot welds inside the white caps or in the maybe in the heating element, but using it seems to eventually fix the bad connection.
Some cartridges I have taken apart (caps) and tried to solder that bad connection to stop the drama.

There are also lots of other fixes to T12 quirks.

Thanks, this sounds promising. I'm struggling to figure out which pin that is on my GX12 connector you're referring to - I have T+, T-, GND, NTC, and SLP, is it one of those?

There's no 100uF cap on the controller board or on the power side, only one 680uF cap - do I just need to put a 100uF 35V electrolytic across +24V and negative?

[redwire]

I don't know exactly what your controller looks like. Quicko has 4 or 5 wire models. I have a Ver3.3 STM32 pic and sch I worked with a Russian fellow on it.
First add 1MEG resistor from GX12 pin 5 (T+) to +24V (VCC). It is so a floating op-amp does not pick up as much noise if the heater cart goes open--circuit.
The 24V bulk cap depends on the controller board regulator circuit and how stable power is on the battery. The mains PSU usually has two 1,000uF caps - you have one 680uF?
Point is, off the battery you have none of that so I suggest 47-100uF 35V added but not mandatory unless more is known about ctrl board.

[spleenharvester]

Gotcha thanks that makes sense, I'll stick a 1M resistor on T+ to VCC, and a 100uF between VCC and GND. Is a 1/4W resistor sufficient in the former?

My T12-958 has no version marking on the PCB but reports HW version 3.20 and SW version 3.2S. I've attached some pictures for anyone else who stumbles upon this thread. The only modification done to this unit is moving the green earth wire from the connector (where it didn't actually connect to anything) to the GND pin of the GX12 connector (under the hot glue I added), everything else is stock. There are two 680uF 35V caps and a choke on VCC regardless of whether on AC or DC. On the AC side there's a 400V 33uF cap and a 22uF 50V cap.

[sam_sam_sam]

You do have to use a 24 volt battery pack you can not use a 18 volt battery pack it gives weird issues I know because I have tried it and I can tell it will work on a 24 volt battery pack

They also have a version that is battery powered with a BMS board but the BMS board has some strange issues with charging the battery cells even if the battery cells are closely matched I talking about no more than 50 milliamperes difference in milliampere hours which to this BMS board is not close enough for it to completely charge the battery pack this is unacceptable performance so I do not use it I have use a battery pack from Lowe's brand power tool and converted a charger base to house the soldering controller board it works pretty good for my use

[redwire]

You know, I don't see anything to change!
That looks like a Quicko STM32 T12 controller, they have better hardware design than KSGER. Not afraid to have a few extra parts and beefier mosfet etc.
The thermocouple op-amp is a 3-Peak TP1541A smt marking 541. I see they already have the 106 resistor pull-up I've been talking about.

Also, the PSU has the 24V battery input and so the 680uF caps are in-circuit then and no need for extra capacitors. There should be a menu to set the low voltage cutoff to say 18V.

That leaves your troubles to the cartridges or maybe the grounding but I can 't see a reason for battery operation to make the unit malfunction so.

[spleenharvester]

Thanks both, that's good to know,

With the Einhell battery the power is a stable +20.9V sagging slightly to +20.1V under load. The DC adapter behaves similarly. Neither is tripping the low voltage cutoff which is set at +19V.

Quecoo do a version that fits Worx, DeWalt, Makita, Milwaukee and Devon batteries, so presumably it is possible to tool battery power them (granted no one has done a teardown of these yet): https://www.quecoo.com/products/t12-...42322818793612

I had presumed they didn't do an Einhell version as it wasn't a significant enough brand, but maybe the power from Einhell batteries is too dirty or something? Is there anything else you can think of worth trying?

Worst case I might buy one of those battery powered ones and a few Milwaukee batteries, it's just more convenient for me to use Einhell because all of my other tools are Einhell. Tbf it would interesting to do a teardown and compare it to the T12-958 to see if they've done anything 'extra' to clean up the battery power.

[stj]

the iron heater is pulsed and it's gonna peak at about 75w
so you need a good electrolytic cap at the board, and decent wires to the battery to avoid dips

[spleenharvester]

It's interesting this battery can run a 700W hoover no problem but struggles with this. I don't really understand enough about it I think. Quecoo have concurred it's something to do with the battery and someone elsewhere thought the [INVERT] error might mean it thinks it's not getting enough power from the AC/DC converter, which makes sense considering it won't know which one it is running from.

What cap do I need/whereabouts do I need to put it? Battery is wired to it with 14AWG wires. I wonder it is worth putting one inside the battery adapter casing so that it's already charged before plugging in. I use this adapter, modified with a female DC jack.

[stj]

a low impedence cap - maybe 1000uf 35v FR series.
right across the battery terminals on the board.

if your battery pack can give 30A then the weak point is probably the connection terminals
as for Amazon - soon as it's mentioned i have to check what shit they are miss-selling!
that round power switch is rated for 12A resistive or 4A inductive load - NOT 30A
i have one in my hand right now!

[spleenharvester]

Cool thanks I'll give that a go.

Yeah first thing I did was bin that power switch lol. I replaced it with a metal DC jack, torpedo switch (one of the decent ones with screw terminals) and 14AWG wires. I think lowest rating in there is 10A max but better than it was at least.

[stj]

well the iron will peak just below 4A so that fine

[redwire]

Also note the battery jack input has two SS26 Schottky diodes 2A each for reverse-polarity protection. Hopefully they can take the current but I would check their voltage drop.

Just to be clear - it gives INVER error message on battery-pack power, with cold heater cart below 70-80C?

I thought the INVER error happens when the TC signal appears INVERTED, tip temp looks like it's dropping despite the heater being on. Backwards-wired thermocouples act like this.
Or the op-amp is unstable and flipping out, not so rail-rail as advertised lol. Picking up PWM noise is common especially on Aixun T3A etc.

I think you have a bad connection to the heater somewhere but why it shows up on battery power, I can't guess. Doesn't make sense.

[spleenharvester]

Yep INVERT on battery power with cold heater cart below about 100C. The temp is increasing as normal before the error so unless something is happening in a split second I think we can rule that one out.

I'm going to try the cap thing and if that doesn't work I'm going to flash with custom firmware, will update