Hakko FX951 parts from AliEx/eBay - just sharing my experience - Page 1
Forum section: electronics / general

author: toli
author_rank: Frequent Contributor
timestamp: April 20, 2018, 09:52:39 am
content: Hi All,I have a Hakko FX951 that's been serving me for 10 years or so. About a year after purchasing it one of the clips on the handle broke, and since they it's been kind of annoying since I would occasionally get a "S-E" (sensor error) on the display when replacing tips. Its easy enough to solve by pushing the tip a bit stronger into the handle, so I wasn't in a hurry to replace it.Over the years I've purchased a few tips from chinese suppliers. While it is easy enough to notice the difference in quality (takes a bit longer to heat-up, doesn't last as long, etc), they work quite well. Well enough for me to be happy with them for the much lower price. I would probably settle on having a large (10-20 tip styles) of this quality + 2-3 original Hakko tips for the things I use most often.However, over the years I tried using two different types of FM-2028 handle knock-offs. Both failed miserably I must say. The first, about a year ago was having problematic contacts, and had a stiff cable. The second I've just received a little while ago, and while the cable feels soft enough, it has many other issues (this one was marketed as a KGSER brand, although the handle ha no logo at all):1 - Visually its different than the original part, and you can see the low quality2 - The heat-up time is X2 slower than with the original handle + cable.3 - There is a significant temperature error. I use an external temperature probe (FG100 knock-off I've purchased to re-cal the HAKKO 470 when I've replaced the heater) to verify it. With the original handle, when I set 355C on the unit I measure 356. With the replacement handle its about 60C higher! I've had a look inside, the knock-off unit has just 3 wires instead of 4, so my guess would be that they are sharing a wire between the sensor and the heater, which adds this huge error.I doubt there's a significant "lesson" to be learned here, since when you get a non-original part, you have no guarantee of quality. However, in some cases the much lower cost is worth the lower quality. I know many other hobbyists, just like me, are considering/using these replacement parts. Therefore I thought I'd share my experience, in case someone is considering these specific parts and would like to know how well they perform.For the asking price of an original FM-2028 I will most likely keep using my old handle with the broken contact, or only replace the plastic part with the broken clip for a chinese knock-off, this should have no affect on performance.

author: KL27x
author_rank: Super Contributor
timestamp: April 21, 2018, 12:07:35 am
content: Interesting. I wonder though if the 4th wire in the original is for the LED ring they removed between the 2027 and 2028? At any rate, the sensor and heater share a wire because they are in series, lol. There's no way to separate them. The third contact on the tip is just the grounding contact.The cold junction of the thermocouple is essentially at the TRS contact rings. I suspect the genuine may have some temp sensing circuitry there for cold junction compensation? (But then, if there's a temp sensor back there, why did they make the tip and handle soo long and dragonfly-like? I always figure they did this so people would not find it comfortable to hold the iron anywhere but the front, to avoid warming up the cold junction with their hand, lol.) Otherwise I find it odd that the clone handle would take 2x as long to heat up, using the same tips. It would be interesting to see what, if any, circuitry is in the handle. Maybe someone could make up a circuit for improving the clone handles. In general, the electronics are usually cheap to copy. It's the plastics and molds that home gamers can't reproduce. If the handle fits and works, physically, pretty close to the original, the electronics should be cheap to make.

author: toli
author_rank: Frequent Contributor
timestamp: April 22, 2018, 07:32:37 am
content: The 4th wire is used, as it is soldered. So I don't think its there from the times of the 2027. However, following your post I've had a second look, and I think you might be right. Seems like it is for another temp sensor, as it has 2 wires coming out of it. However, it is molded within the unit so it would be difficult to see what is there exactly.This wire (and sensor) isn't present in the chinese knock-off, which can explain the source of the error.

author: 2N3055
author_rank: Super Contributor
timestamp: April 22, 2018, 08:42:22 am
content: It is a NTC for cold junction compensation. It is shown clearly in their patent schematic...

author: toli
author_rank: Frequent Contributor
timestamp: April 22, 2018, 01:50:34 pm
content: Perhaps the chinese knock-off manufacturer should read this patent too

author: thm_w
author_rank: Super Contributor
timestamp: April 23, 2018, 10:41:02 pm
content: Some T12 handles have the glass NTC and some don't, and some bases have a connection for it while others do not. I mentioned in another thread how to modify the base to support the handle with additional wire.From these links I only see three wires going to the handle, so its possible all 951 station/2028 style clones don't have it either:https://leisto.blogspot.ca/2012/12/fx-951-soldering-station-disassemble.htmlhttp://forum.eepw.com.cn/thread/234024/1This would make modification time consuming/costly as you would need to replace the cable with one that has an extra wire as well.The non 2028 clone handles can have 4 or 5 wires to support the NTC and vibration sensor.