Chinese USB soldering iron longevity? - Page 1
Forum section: electronics / general

author: kalel
author_rank: Frequent Contributor
timestamp: June 02, 2017, 10:33:16 pm
content: Hi there,I have ordered and used the USB soldering iron from China (I only see one type so far, the one controlled by the 555 timer).Anyway, after some uses (I think about 10 or 20, but definitely not too many) it stopped working properly.The symptoms were that the LED would light up, but the iron would not heat up. Or it would heat up slightly or irregularly (perhaps it was just a few last attempts of the iron to work). The LED would continuously light up while moving the cable around which leads me to believe it's probably not a bad connection. Anyway, upon trying to open it, I wasn't able to open the screws properly at all (wrong screwdriver type or just bad screws, I don't really know), so I wasn't able to even try and guess what the problem is from the inside (measure if any voltage is reaching the heating element or such).Without knowing what the problem was, and even if I knew, that doesn't change the question. I assume a lot of people bought these just to experiment.Can you share your experience regarding the longevity of this item?If you used it more than a few times, does is still work properly, and if not, what are the symptoms?I'm trying to figure out if I should order another one, but if they really last this little - meaning it wasn't a defect, I should probably avoid it.Thanks a lot!

author: kalel
author_rank: Frequent Contributor
timestamp: June 02, 2017, 10:55:06 pm
content: Quote from: blueskull on June 02, 2017, 10:37:27 pmNo problem with Chinese irons at all. Just wondering about the specific USB iron model as it's interesting.

author: kalel
author_rank: Frequent Contributor
timestamp: June 02, 2017, 11:20:31 pm
content: Quote from: blueskull on June 02, 2017, 10:56:28 pmIn the case of the soldering iron, being USB just means that it works on low voltage, so you can either power it by battery (power bank) or a high current USB power supply (or any 5v power supply if you cut the wires - there is no USB data com in the iron of course). This makes it portable, and handy in some cases. With a power bank, you also don't have to worry about grounding or being connected to the mains in any way. Not overly important, but it's a slight advantage.That doesn't mean that I think that a USB soldering iron can replace a decent temperature controlled one with various tips available or work well in longer soldering sessions. I'm just trying to inquire a bit more about experiences of longevity of this specific item, as my first experience was short.

author: sleemanj
author_rank: Super Contributor
timestamp: June 03, 2017, 04:41:33 am
content: I keep one of those cheap "USB" irons in a drawer but only for unusual uses, like fixing the normal soldering iron or when I need to solder something on a car.Don't know about longevity, but I wouldn't expect it to last for normal everyday use. Very useful to have around though as a spare.

author: P90
author_rank: Frequent Contributor
timestamp: June 03, 2017, 06:37:43 am
content: best to use those from a usb battery powerbank. Be careful if using a usb mains power adapter, since voltage leakage to the tip could potentially damage sensitive electronics...

author: kalel
author_rank: Frequent Contributor
timestamp: June 03, 2017, 08:09:53 am
content: Thanks and those are some good points. I think it's most safe to use it from a power bank, and also quite portable (almost as much as a battery soldering iron).But regardless of that, my unit broke after just a few uses (10 to 20 is an estimate, from what I remember I soldered one small - few parts only - electronics kit from eba and used it a couple of times for other quick things). I might order another one and see if it can last a bit more this time.Some videos mentioned that the only temperature regulation it has depends on the 555 timer - an "on" period where it reaches very high temperatures, over 400 degrees C, and an "off" period to cool down, so perhaps I just activated it too much by usage and it reached a too high temperature, causing something to fail more quickly than it might have otherwise - but on the other hand you have to use it while working and waiting a long time between joints would be strange). Perhaps it would be interesting if you had a potentiometer to affect the timing, but probably it wouldn't be very useful in the end, especially as I'm still not sure exactly how the temperature is controlled.One really impressive thing about it was the initial heat up time. It's faster than any soldering iron I've used before as it really works after just a few seconds.

author: P90
author_rank: Frequent Contributor
timestamp: June 03, 2017, 08:42:38 am
content: Quote from: kalel on June 03, 2017, 08:09:53 amYes, those cheap USB irons don't have any temperature control, the 555 merely is acting as a timer to turn off the iron, and it turns back on via a vibration switch or finger touch. The element is supplied with full voltage through a mosfet. These irons aren't designed for high duty cycle use...

author: kalel
author_rank: Frequent Contributor
timestamp: June 03, 2017, 11:50:01 pm
content: It seems the price has slightly dropped, so they are available for around $4.5 with free shipping now. Interestingly, the tip for it costs about the same as the soldering iron + tiny stand + tiny amount of solder + usb cable standard pack.I think I will likely risk getting another one, try using it as little as possible, but also hope it doesn't die too fast.In case it does, any tips for opening the screws? Perhaps I just had the wrong screwdriver or they were a bit faulty, but I could not really open the unit without drilling, which ruined the PCB. I did try the heating element and it appeared to work on 5v, but took longer to heat up than with the circuit (so possibly damaged or the circuit does some stepping up or something else entirely).

author: Nusa
author_rank: Super Contributor
timestamp: June 04, 2017, 12:27:27 am
content: I have a butane soldering iron I acquired over 25 years ago for those times I wasn't near electricity. It lives in my portable toolkit and still gets used once or twice a year. They're still around and easy to buy, if portability is the prime consideration.

author: sleemanj
author_rank: Super Contributor
timestamp: June 04, 2017, 01:20:59 am
content: I recall that bigclivedotcom took one apart on his youtube channel I think, if you dig about you should find it, might guide you in disassembly.Edit: here it is

author: jonovid
author_rank: Super Contributor
timestamp: June 04, 2017, 04:48:05 am
content: usb short circuit protection

author: kalel
author_rank: Frequent Contributor
timestamp: June 04, 2017, 06:46:45 am
content: Quote from: jonovid on June 04, 2017, 04:48:05 amWhat do you mean?

author: jonovid
author_rank: Super Contributor
timestamp: June 04, 2017, 04:03:54 pm
content: Quote from: kalel on June 04, 2017, 06:46:45 amis this The War of Currents 2.0 ,just how many watts can a 5 volt USB take?do we expect to see USB power tools next?https://en.wikipedia.org/wiki/War_of_Currentshis motherboard went up in flames \/ image off the web. short circuit ?

author: P90
author_rank: Frequent Contributor
timestamp: June 04, 2017, 04:12:22 pm
content: Quote from: jonovid on June 04, 2017, 04:03:54 pmever heard of a USB powerbank?

author: kalel
author_rank: Frequent Contributor
timestamp: June 05, 2017, 01:26:47 am
content: It would be nice if motherboards indeed had some type of resetable fuses or other protection on USB ports considering that these days all kinds of USB devices do exist, some of which draw a bit more power than they should. Also, a device that doesn't work well might cause a short circuit and that should definitely be protected against - and maybe it is. Anyway, there's no clear disadvantage to having some protection (perhaps the cost).In some cases, there are computers with built in high current charge ports (for fast charging and such) that might support enough current for the soldering iron.Additionally, there are USB power plugs with 2A or perhaps even 3A support, but as seen in the video, this might be dangerous for some sensitive electronics. I'm sure the same goes for any ungrounded soldering irons, which I have used, fortunately without getting a shock yet.As for the best and safest way, that's definitely using a power bank.Some other higher performance USB devices usually have a li-ion or li-po battery and simply use USB to charge. In some way that's the same as using the soldering iron with a USB power bank.

author: brainwash
author_rank: Frequent Contributor
timestamp: June 10, 2017, 09:43:56 pm
content: Replying to this topic instead of the old one (https://www.eevblog.com/forum/reviews/usb-soldering-iron-for-real/).I've had problems with my USB soldering iron, which only gets used a couple of times per year, in that it was really hard to turn on while on a USB powerbank, esp. while in car. It doesn't have a vibration sensor. This is my go-to soldering iron for doing light things inside my car or on my motorcycle.Strange thing is, the iron turns on almost every time with a mains USB supply, but rarely with a power bank. That would be a great investigation why that happens.Anyway, since the touch sensor requires that a small current be sunk between it and the ground pin, the best solution was to solder a ground wire, poke a hole with a  soldering iron inside the case, bring a ground pad outside, next to the touch pad. This way I get 100% activation, instead of <5%. If the ground pad is mechanically floating, you can bend it to touch the ground pad, so that the iron is always on. But, in my case, I think the 'touch every 25s' compromise is better than safety.http://imgur.com/a/rPzP4