Looking for a soldering power supply potential candidate for a Weller TCP-S iron - Page 1
Forum section: electronics / general

author: VinzC
author_rank: Frequent Contributor
timestamp: December 31, 2015, 10:45:57 am
content: Hi all.Decades ago, when I was a student, I bought aWeller TCP-S soldering irononly — budget mattered, you know what I mean. I also built an AC power supply for it (although I don't even remember actually making it!) and it has served me well so far. As I will dive into SMD soldering (better later than never) I'd like to know if there's a power supply with temperature control that would fit my iron.This iron has three wires: blue, brown and green/yellow (Earth/ground). The above-linked Farnell page says it has different operating temperatures (260°C, 310°C, 370°C, 425°C) but looking at those three wires I fear it's not compatible with a power supply that includes temperature control, could someone confirm? But as it works based on the Curie effect maybe I can keep it just like that and not bother.Does anybody have any advice?Happy new year's eve to everyone.

author: Ian.M
author_rank: Super Contributor
timestamp: December 31, 2015, 11:01:29 am
content: The power supply is just a 24V AC transformer 50VA or greater. Green/yellow is earth to the tip.It uses Curie point temperature control set by a ferromagnetic alloy pellet on the shank end of the bit. Genuine Weller TCP bits are (or at least used to be) stamped with the first digit of the temperature in degree F on the pellet. There is no easy way of converting it to variable temperature as the whole Magnastat switch assembloy would need to be replaced with a temperature sensor, and the bit replaced with one that had no alloy pellet, but instead was machined to closely couple to the temperature sensor.Caution: the Magnastat switch tends to burn its contacts or stick on resulting in drastic overheating. You may want to rewire the iron so the switch only triggers a TRIAC in the power supply, instead of carrying the full heater current.

author: SeanB
author_rank: Super Contributor
timestamp: December 31, 2015, 11:10:55 am
content: Easy to convert them, the magnastat pellet can be pulled out leaving a cavity, and the later Weller irons used the same tips, elements and sleeves, just having a thermocouple down the middle in place of the magnastat so that it touched the tip rear.

author: ciccio
author_rank: Frequent Contributor
timestamp: December 31, 2015, 11:12:07 am
content: The Weller TCP iron is powered directly by 24 V AC , from a transformer built in the base.Temperature control is done by a thermostatic switch built in the handle, where a magnet is attracted by the back of the tip, built with a ferromagnetic material which changes it's magnetic properties at a predetermined temperature.So when the set temperature is reached the magnet is released and power is switched off. When the temperature, decreasing, reaches a lower point the tip changes it's magnetic state, and the magnet closes the switch to re-heat the iron.Tne Curie point of the tip, thus the nominal operating temperature, is indicate by a small number stamped on the back of the tip. I remember I used only tips marked "7" , corresponding to 375 °C.All you need is a box with a 24V ac / 50 VA transformer, a suitable mains switch, mains fuse, power cord and a connector for the iron.The last one may be the most difficult part to find. You can even remove the corrector from the iron cable and use a terminal block for wiring the cable to the base, as was in the older models of TCP.I believe that the original base and stand are still available, but you can buy an HAKKO with the price they ask for them.Best regards

author: ciccio
author_rank: Frequent Contributor
timestamp: December 31, 2015, 11:22:36 am
content: Others before me had explained better the operation of the TCP iron when I was writing...Regarding the switch in the handle, I never experienced a "glued" contact: sometimes it remained open > no heat.Other times the magnet was blocked inside the handle, by corrosion or by some deposit coming from solder smoke or water used on the tip cleaning sponge.I found that a good protective measure was to tap the handle on the workbench every day: at the production line we did that, and thermostat locking was practically non-existent.

author: VinzC
author_rank: Frequent Contributor
timestamp: December 31, 2015, 02:49:08 pm
content: Thanks guys for your insights. I just would like to add — my bad, I didn't so it's probably confusing — I do not intend to hack my iron. Instead I was curious to know if I could buy an off-the-shelf power supply from Weller that would work with my iron. From what I've read of your replies, that looks unlikely. But I'm perfectly fine with it.Your replies also clarified what I've read on the Farnell page, i.e. the temperatures they indicate are the soldering tips'. My tip is marked7hence 370°C. It must be aPT-P7orPT-P8model (Weller's weak spot probably is the verbosity of their specs...) Shall I deduce the figure inPT-P7andPT-P8is the marking? So if I opt for aPT-H6is that okay for SMD?

author: Ian.M
author_rank: Super Contributor
timestamp: December 31, 2015, 04:00:09 pm
content: The last digit of the bit part number is the temperature, in multiples of 100°F. Therefore your tip is 700°F (370°C). You *may* find a 600°F (315°C) bit preferable, but I've done a lot of SMD work with a PTAA7 bit which was the standard one supplied with Weller TCP irons.

author: VinzC
author_rank: Frequent Contributor
timestamp: December 31, 2015, 05:31:07 pm
content: Quote from: Ian.M on December 31, 2015, 04:00:09 pmExcellent! I love it when I have nothing to do...

author: anotherlin
author_rank: Frequent Contributor
timestamp: January 04, 2016, 08:13:14 am
content: Quote from: ciccio on December 31, 2015, 11:12:07 amI investigated that recently because I bought an (old) Weller IG101 desoldering "station".It seems the WTCP connector is off the shelf Amphenol 3 pins DIN connector. Later models also use Amphenol DIN connectors, albeit 6 or 7 pins.That's not difficult to find and not that expensive, Mouser has them for around 3-5 euros.In my case, the IG101 expected 24VAC 2 amps from a Weller 3 pins (2 used only) connector (same as WTCP), along with compressed air (for desoldering).It has a electronic (triac) to control temperature of the iron (6 pins) and a solenoid controled venturi valve (for vacuum).Because I was in a hurry to make it work, I basically bought a 50VA 24V transformer, opened the box and plugged it.It works just fine.The thing is the transformer cost me 29 euros at my local electronic store and I guess it would have cost me a little less (let's say 15-20 euros maybe) at conrad.fr.Whereas a used WTCP power supply (check ebay.de for instance) can be had for 30-35 euros + shipping.I believe it's not worth the hassle to build a supply from a transformer, just get a used one from ebay.

author: Gyro
author_rank: Super Contributor
timestamp: January 04, 2016, 12:55:33 pm
content: It's quite easy to modify the TCP series to add Triac or SSR switching to prolong contact life. As the magnetic switch element is by far the most expensive part in the whole iron it's well worth the time and component cost to do it....http://www.vintage-radio.net/forum/showthread.php?s=13d2c47624e9e974f605114ad7c9b078&t=67035