Soldering irons and their tips come in a wide range of formats and styles, with the (originally Hakko) T12 being one of the more interesting offerings. This is because of how it integrates not only the tip and heating element, but also a thermocouple and everything else in a self-contained package. In a recent video [Big Clive] decided to not only poke at one of these T12 tips, but also do a teardown.

With a simple diagram [Clive] explains how these T12 elements are then used to regulate the temperature, which isn’t too distinct from the average soldering iron with ceramic heating element, but it’s still nice to have it all integrated rather than having to try to carefully not damage the ceramic heater while swapping tips with the average soldering iron.

Inside a modern T12 style soldering iron element/bit
https://www.youtube.com/watch?v=CdF3tjVUvXo

0:00 Introduction
3:01 ALLPCB
3:46 Details of the Handpiece
7:13 JBC Base Unit
11:21 Teardown
16:21 User Interface and Options
19:38 Loading solder
22:46 Testing some soldering
24:53 An upset Steve

I got this tester to check the temperature of various soldering irons. Having tried testing tip temperature with a normal thermocouple with very random results, I thought it would be quite interesting to see what was special about the thermocouple used specifically to test iron tips.
Although labelled Hakko, I don’t know if it’s a genuine Hakko brand unit.

Slightly weird circuitry. This took longer to reverse engineer than expected, but yielded new information on the thermal sensing of Hakko-style soldering irons.
The default temperature of 500C (932F) is quite dramatic for a soldering iron, but there is a way to hack it to a lower temperature if desired.

The circuitry is a bit weird, in that the main control chip may have a stand-alone comparator section, but also monitor its activity externally and override it to shut the iron down. At least, that’s my first guess at what’s happening. Alternatively it could be ensuring the MOSFET is forced off in sleep mode, although the sleep current draw is very low at about 1uA.

https://www.miniware.com.cn/product/ts101-smart-soldering-iron/

Yes, I know it’s silicone – but the majority of silicone insulation isn’t rated for anything over 200C, and much of it is 100C or less. The 200+ stuff is also virtually impossible to buy online.

Checked with people who have Hakko irons, same thing – the FX888 handpiece cable can take 850F no problem.

I have opened up a fair number of Objects before and almost never found another Whole Object inside like this. Ryobi! What are you doing!

The title of this video describes the primary punchline, but it’s also just an overview of the whole tool’s build quality, which I think is worth your time! Ryobi did some wild stuff here!

I’ve also learned that Hakko irons have exposed ceramic elements, and it sure looks like they use PVC cords. To which I respond: that’s why I bought a Weller.

Chapters:
00:00 The problem
01:46 Existing solutions
05:57 Ryobi options
10:20 Station overview
21:21 The first issue
26:13 Taking it apart
29:17 The insides (The Big Reveal)
34:36 Other quality issues
39:33 Chassis quality
41:34 Conclusions
42:28 Second Ryobi product
46:05 Outro