Experimenting with Flyback Transformers 3rd Prize – More Than I Expected!

The Experimenting with Flyback Transformers Design Challenge, sponsored by Bourns, was definitely a challenge for a novice such as myself. I wasn’t helped by time constraints due to competing demands, but I decided to put in a solid push towards the end to make sure I wouldn’t leave my promises unfulfilled.

Early in February, the results for the challenge were announced. Looking at the superb postings from javagoza and Anthocyanina  made it clear to me that I wasn’t going to be placing in the first or second prize categories, in spite of their good spirited encouragement. But I was fine with this – I knew I had not quite reached the same standards as they did, nor did I quite reach the high standards that I did in the past.

But what did surprise me was the generous offer rscasny  made, of a third prize, which was not originally on offer. I had a choice of two options and ultimately, I made the choice of a Metcal GT120 Soldering Station which was used and supplied without warranty. I did previously apply to the Metcal GT90/120 RoadTest and was not selected, so this would be a great opportunity to make up for it, especially as someone who has a Metcal PS-900 and a Weller WXsmart, the latter thanks to a RoadTest.

Unboxing

My prize was perhaps the first to arrive, being “on-hand” for immediate dispatch. I didn’t quite have the time to blog about it, as things have been quite hectic.

For a soldering station, I was surprised at the size of the box and the weight. I was pretty sure I got more than I had bargained for.

True to their word, the station was used – the seals were broken. But there’s nothing wrong with a used piece of equipment, especially if it’s been treated well.

Inside were four major boxes – two were marked as handpieces, one was a stand and the other was the main unit.

Main Unit

Inside the box of the main unit, it seems like there’s a bit of a mess of documentation.

The unit was safely packed underneath along with a US mains lead. Surprisingly to me, this was a shielded mains lead – high quality stuff, but perhaps just to limit potential EMI issues. I had to cut the plug off to wire in an Australian plug (noting that the wires are not technically compliant to our voltage, colour coding or wire order, but this is not a major issue in practice).

The documents included an introduction guide, a quick start guide and this dispatch note for a Microchip DSPIC Starter Kit Board that wasn’t included. Interestingly, the note actually seems to be working between the UK and US arms of element14 with the order placed by a familiar name (a former RoadTest Administrator who was around when I first started).

Hold on … what is in this envelope with a bit of blue painter’s tape?

Well, this was unexpected!

A letter, likely written years ago, by the one-and-only James (@baldengineer). As it turns out, I’m handling a set that he himself had featured in a Workbench Wednesdays episode. What an honour it is! As a bonus, now I have a few stickers too … thanks!

So it would seem that the unit wasn’t quite packed in the original way, so we actually have the main unit, the power supply and a handpiece with retainer rings all in the one box.

The main unit is a bit of an odd shape. The curves and flat segments sort of remind me of an arcade machine, but somehow backwards.

The power input from the supply is on the rear. They’ve used a Kycon KPPX-4C type connection, no doubt for its latching robustness and the presence of an earth shield for ESD reasons. There is a USB-A port on the rear for firmware updates and a power switch.

As this was a RoadTest unit initially, it seems to be of an early serial – 000427! The manufacturing date of 22^nd January 2021 makes this now three years old. It is interesting to see the rating underneath says 30W nominal, 120W max. It would seem that many times, the numbers on stations can be a bit inflated.

The power supply is a quality Meanwell GSM120A48-R7B which is rated at 48V 120W. Because of the way Meanwell wires up its supplies, Pin 1 and 4 are +ve, while Pin 2 and 3 are -ve. The ground is connected to the shield.

This is different from many other pre-made KPPX-4C supplies which are 1-2 +ve and 3-4 -ve, so don’t go swapping these around!

The handpiece has a nice thick silicone grip and stainless threads to which the locking collar attaches to retain the cartridge and tip or cartridge-tip.

The attachment of the strain relief is a bit questionable.

The handpiece attaches to the base with a DIN-type connector with a latching feature.

Stand

The stand allows for the handpiece to rest safely. While this kit contains two handpieces (which was more than I expected), it only has one stand. The stand has some positions where tips can be stored.

The body of the stand seems metallic and the design accommodates both sponge and brass wool users.

A special cross-shaped gasket is provided to help keep the solder from flicking when using the wool.

Curiously, while there are rubber feet to stop the stand from sliding around on the desk, the base is made of plastic.

Handpiece, Cartridges and Tips

Inside the box for the GT-HP-T4UF handpiece, I found the handpiece still in bag with the disconnected strain relief that I was warned about, a quick-start guide, the heater cartridge and locking collars.

In the box for the other handpiece, I found the GT6 series heater cartridge and four cartridge-tips.

But the biggest surprise to me was what I found in the main unit box …

… a whole assortment of GT4 and GT6 tips – more than I could possibly ever use. Some of them had been opened for demonstration, and a couple had been barely used, but this is like hitting a goldmine in terms of accessories. Tips can be a big investment (often ~AU$15+ each) and having the right tip could make your soldering jobs a lot easier and more reliable.

As a result, I was totally floored by what I had received. Not only was it a Metcal – a highly reputable and respected brand in the soldering market, but it was complete with two handpieces, a stand, an array of tips and assorted tip-cartridges. It was more than just a system (which usually comes with one handpiece, one heater cartridge, no tip and one stand), which is what I was expecting. This was totally unexpected.

First Impressions

At first glance, while the station itself seems compact, the power brick is certainly not. Because of the stiff cable between the station and the power supply which appears sheathed in ordinary PVC, the user needs to be a little careful about positioning and routing of the cable.

The orange colour of the station is offset by black trim and this seems rather unique. Nevertheless, having the power switch and USB firmware upgrade connection on the rear is a little less obvious than it could be – especially if one needs to power off the iron in an emergency.

User interface is by four rubber “calculator-style” push buttons underneath a backlit white/blue monochrome matrix LCD.

The design of the menus is relatively simple, having just two levels of depth. It seems a lot less complex than I would have imagined.

There is some level of privilege separation allowing locking of temperature settings for quality management reasons. However, I didn’t take much in the way of time to explore this as yet.

The handpieces connect using a DIN-connector of some sort, similar to those used for MIDI, but with a latching feature. It appears that there are a broad range of compatible handpieces, tips and heater cartridges available. The array of options can be a little confusing at first, which is why reference to their Tips and Cartridges Guide is recommended. Some tips are intended for use with a heater cartridge (GT-HC) while other tips have heater cartridges integrated (GTC) and are designed to plug right into the handpiece as “tip cartridges”. Both T6 and T4 handpieces are usable with the GT120.

Holding the handpieces in the hand, I do love the silicone grip that feels nice and “squishy” without being sticky. The silicone cable, on the other hand, does feel a little tacky after the years and the strain relief either has come off (as per the letter) or seems glued rather poorly. The balance in the hand feels good and the diameter of the handpiece is quite normal. This is in contrast to the Weller WXsmart which seems to have reduced tip-to-grip distance and kept diameters a bit smaller for finer control. I’ll have to do some actual soldering to see which I like best, but I feel that this is probably not a major disadvantage. There is a supplied silicone pad for removal of tips/cartridges and a limited amount of tip storage on the stand.

The stand is something I do like, with the option of sponge or brass wool, the silicone gasket around the brass wool stops it from escaping and ensures that solder doesn’t “flick” across the room because of a careless tip cleaning operation. I think that’s a nice touch.

During soldering, it seems the user interface displays the tip temperature and the power being delivered to the tip as a percentage and as a bar graph. Below that is the cartridge information (where available). I find the display a little visually busy as the bar and percentages update frequently, as the power level really doesn’t need to be so prominent in my opinion. Alas it does seem fashionable to do this … so I guess that’s not a downside as such.

The unit is firmware upgradable and I have a feeling that the firmware on it is out-of-date. But unfortunately, I’m out of time … so that will have to wait until my return from my hiatus.

Conclusion

While I haven’t been able to give the GT120 the full RoadTest treatment just yet, as I’m preparing soon to embark on my holiday and am already on a semi-hiatus, I will probably do so just as soon as I get back. This would mean upgrading the firmware, doing some soldering as well as a few tests of the temperature regulation and power consumption.

But until then, I am utterly and truly grateful for this wonderful, unexpected and generous third prize. In fact, it was much more than I had expected, to the point I felt that other prize winners might start getting a bit jealous. After all, how many people can say they have a soldering iron with a range of tips? How about a hand-signed letter from the one and only
baldengineer ? Aside from being a useful tool, it will also be a chance to get some practical experience with a product I had wanted to review back in 2021.

That being said, not having soldered with it just yet, I’ll have to reserve my complete judgement on the system until later.