Hakko T12' cartridges malfunction (SOLVED)

[runaway]

Hi guys! I came across with a kind of pretty weird difficulties when started a new pair of T12' tips ('B' series - short cone shaped for small SMD's). So when I stuck them into the handles (got a pair of it powered from single ATX power supply DIY structure based on Chinese 'T12 soldering station kit' bought on AliExpress - I often use it as a soldering tweezers) - both of them 'speed up' themselves in a very 'peculiar way' as D. Bowie sang. Well, firstly I got '500' on both displays for a few seconds, then '450' (in spite the target temperature has been set to '250' or so). This lasted for a half of a minute, then tips began to warmed up slowly, but in a few minutes they hardly managed to melt a small piece of rosin. Then I got tired of it and set the target temperature to maximum (450 C), and, in the end, in a pair of a minutes (as usual it gains its target temp. in a few SECONDS) I've got a pair of pretty good T12 tips that works just perfectly, as ever. Then I set the target down to 250 C, then switched it off, let them cool down to the ambient, and then run them again... Any problem! So now they work just as any other ordinary T12 tip. So now here is my question: is anyone ever faced this and whether somebody has a kind of plausible explanation of the phenomena? Thank you!

[GreyWoolfe]

Just curious, are these real Hakko tips or clones.  If clones, QC can be an issue.

[runaway]

Sure clones, regarding to the price (AliExpress). And you know, these clones do satisfy me thoroughly. I have a dozen of it, they work just perfectly, but ALL of them were needed to be 'activated' before use: a brand new one (just from the packet) at first makes the digits on the display to jerk in a chaotic way around the target for about a hundred 'degrees' (while there wasn't any sufficient fluctuations of the tip's real temperature). Then, after a minute, digits' 'virtual' fluctuations narrow down to a couple of degrees both up and down (+/-) from the target. ALL of my tips had been passed through such an 'activation peculiarity', but the last pair had it just hypertrophied (while the seller on AE remains the same).

Regarding this I would like to ask - how do they manage to HEAT the tip and MEASURE its temperature by A SINGLE PAIR of contact rings on the cartridge? o_0

[JackJones]

Might be a problem of poor contact with the tip and handle? Maybe there is some sort of storage grease that burns off after a while and then it starts working properly and makes a good contact? That's all I could think of really.

I'm not familiar with the T12 tips, but there should be 3 contacts on them.

[runaway]

No way - usually I sand contact areas with a pinch of dry dishwasher powder and a piece of soft cloth (sometimes with a piece of thin sandpaper): both contact springs in the handle, and the areas on the cartridge' contact rings are opposite to them. Then I lubricate these surfaces with a droplet of thick silicone oil between my fingertips.

The other possible problem may be under the plastic cap of the cartridge (it can be removed easily). The cap covers a thermosensor' contacts, and sometimes (pretty rare) they may not be good - people advise to solder them through with good active flux.

But both of them aren't my case. I've got reproducible, stable bloody 'activation' that just awakes my curiosity...

[runaway]

My apologies and some clarifications: the contacts under the cap do matter very much. Both cartridges have poor contacts under the caps, both refused to work the next day, both were repaired successfully just 10 min ago by soldering the pressured contacts (depictured above) with saturated water solution of orthophosphorus acid, the remains of which were removed then with warm water, tooth brush and alkaline loundry soap. No other flux I have at my workshop worked well in this case. The caps were secured back into places with a droplet of super glue.

I think there are only two operational contact rings on the cartridges. The third (big) one is the grounding of the tip, and it doesn't take part in control process. I think that MCU feels somehow the changing of the heater's resistance, or the sensor is just connected in parallel to the heater coil so no third contact is needed.

[runaway]

As the bonus: the tip (wise advise) concerning the cartridges... Don't buy cartridges with thin and long tips - they have poor thermal conductivity so the very working tip of the soldering tip suffers from lack of temperature, it almost always sticks to the soldering joint, so the great idea of the T12 just turns into profanity. The best series meet this point: K, B, C4, D4. These four types can perform almost ANY soldering mission. In other words, your soldering tips must be THICK and SHORT. Do not look at thin and long ones (JL02 like) - the wasted time and money. Good luck!

[runaway]

Some pictures of failed T12 cartridge (heater internal cut-off due to poor contact welding). No thermosensor is detected. The system is controlled by the signal from the heater coil.

[thm_w]

Good photos. There should be a thermocouple in the tip somewhere:
https://hackaday.io/project/94905-hakko-revenge/log/144548-hakko-t12-thermocouple-is-not-type-k

As the bonus: the tip (wise advise) concerning the cartridges... Don't buy cartridges with thin and long tips - they have poor thermal conductivity so the very working tip of the soldering tip suffers from lack of temperature, it almost always sticks to the soldering joint, so the great idea of the T12 just turns into profanity. The best series meet this point: K, B, C4, D4. These four types can perform almost ANY soldering mission. In other words, your soldering tips must be THICK and SHORT. Do not look at thin and long ones (JL02 like) - the wasted time and money. Good luck!

I agree for general use, but sometimes it is necessary if you are dealing with tight areas or small components. Some iron firmware has temperature compensation for the smaller tip styles, but its easy enough to bump up the temperature manually. I like the JL02 tip, not nearly as good as the metcal equivalent though.

[runaway]

I think T12 thermocouple is a 'parasitic' one, made by means of structure itself (heater wire + terminal wire), for any welded joint of two different metals gives us a kind of thermocouple. I mean the use of this 'structural' thermocouple is the bright example of smart design, not less!

Controller may heat the coil firstly, and then has certain time to 'have a look at' that 'thermocouple' and measure its mV's... So the control process is divided to these two CONSEQUENT (not parallel) procedures. As a result we have TWO contact rings, not THREE. Smart idea, smart design! Thank you very much for the link!

JL02... (( My Chinese controller doesn't work properly with these cartridges, otherwise you set the target to '300' or even higher. Type 'B' (short cone) does work instead of that ones just perfectly.

[runaway]

And another one important notification: some AliExpress sellers advise to 'activate' brand new cartridges by powering them from the 12 VDC up to 24 VDC for several seconds in order to narrow down the digits instability on the display, or even in the case of malfunction the description of which this topic was started by... I've came across with it just yesterday evening... o_0

[stj]

ATX psu??
your using 12v to drive an 18-24v soldering setup??

[runaway]

Yes, modified ATX PSU. Negative - 12 VDC boosted up to positive + 12 VDC amperage level. So they are connected in series; the result is 24 VDC, 13 A max.

[stj]

well something's wrong, because my JL02 works great. 

[runaway]

Mine too, but the target must be set to 300+... It isn't the work I want to enjoy... JL02 should be thoroughly hollow inside and has tiny bead of thermocouple just in the very tip (bent) of itself - that should be 'great work' I guess! ))

[Bala]

Thank you Runaway, for the useful information and photos you had posted on T12 soldering iron tip.
I bought my T12-X Plus Soldering Station in October 2022. Yesterday, when I turned the switch on, the display showed "Tool error". When I tried with a new tip, it worked normally. I thought that the tip's life was over though it looked unlikely because it was less than two years old.
Today, I did a google search and came across your post on the subject. Based on the info you had provided, I removed the tiny white cap of the tip and crimped the two wires firmly to the contacts. When I inserted this tip and turned on the power switch, there was no error message and the tip worked normally. What a relief!
For a working T12 tip, the resistance between the contacts is about 8 ohms. If a non-working tip shows much higher resistance, the likely reason is, the wires from the heating element are not properly connected to the contacts. The easy solution is to use nose pliers and crimp the contacts to the wires. A better solution would be to solder the wires to the contacts for which you will need the right flux.
Thanks again for the tips on the tip.