FX-888D: Bad calibration, or melt-proof solder? - Page 1
Forum section: electronics / beginners

author: BassClef
author_rank: Contributor
timestamp: August 26, 2023, 11:59:00 pm
content: Is “the industry” using lead-free solder that will not melt even at 899 F (482 C)? Or is my Hakko FC-888D soldering station grossly miscalibrated?I was attempting to replace the rotary encoder in my FeelTech/KKMoon FY-6800 function generator. I was unable to unsolder the rotary encoder from the board. The encoder has 3 tiny electrical connections, plus two larger tabs to hold it in place. The solder blobs on the latter would not melt no matter what I did. I increased the heat on my Hakko FX-888D up to maximum (899 F) in 50 degree increments. I used a flattened tip 1.2mm wide, which came with the station. I also melted a bit of 60-40 solder on top of the connection to add thermal mass. No joy. When I later wicked away the 60/40 solder, the OEM solder remained, seemingly unchanged.I’ve never encountered this before, but I’ve mostly worked on equipment from the pre-lead-free era. The Hakko seems to work fine at 650-700F settings with my 60/40 solder. Yes, I know the difference between setting the temperature and calibrating the unit.I have a K-type thermocouple for my Tek DMM 850, but it is only rated to 400F. I took a chance and ran it from 400 to 600 F with the junction fastened to the iron tip with twisted brass wire. The meter read 30 to 60 degrees lower than the setting on the Hakko. I’m not sure how accurate this is. I’m not going to recalibrate the Hakko until I have more data. I’ve ordered one of those cheap Chinese clones of the Hakko FG-100 thermometer to check further. I have a few days to return the FX-888D to Amazon if it turns out to be bad at high temperatures.Any further thoughts or suggestions?

author: coppercone2
author_rank: Super Contributor
timestamp: August 27, 2023, 12:02:25 am
content: 50f error sounds about right without the little special solder measuring thermocouple thingy.See if you can melt it with a small torch. or a automotive/gun style soldering iron, they get real hot.its probobly a thermal mass issue. do you have a big chisel tip? like a 4mm?

author: JustMeHere
author_rank: Frequent Contributor
timestamp: August 27, 2023, 12:58:06 am
content: What tip are you using?

author: Electro Fan
author_rank: Super Contributor
timestamp: August 27, 2023, 01:06:35 am
content: There is a chance the 888 is not properly calibrated. The user interface can be confusing. If you look in the manual you will see that the temp change button presses for normal operation and calibration changes is only a button sequence or two different. If you happen to get out of the intended normal op function and into the cal function the temp UI can get scrambled up.If that happens you need to get it unscrambled and that can be slightly confusing and frustrating using a DMM temp probe. The FG-100 clone can help guide you back to some pretty good extent and at some point as you get it better dialed in the DMM probe can help triangulate further toward an accurate temp. At the end of the day your solder should melt at some sane to plausible temp if you use a reasonable size/shape tip.Once you get it recalibrated back to a temp that makes sense then you don’t have to worry too much about the exact temp - you will have suitably fast melting for a baseline tip/PCB/component combination and you can then adjust with other tips or temps as needed based on what you are soldering. The 888 is not high end but it should be very consistent and reliable after you give it about 30-60 seconds to heat up to your default target temp after turn on.Once you get it closely calibrated you can spend some more time observing how fast the melting goes for your default tip/component/PCB and then decide what temp gets you in and out fast but doesn’t overcook the component or trace. At this point you aren’t trying to cal the readout you are just picking your preferred temp. Once you have it highly dialed in to a temp that makes sense for your typical need it should be a joy to use.edit: this might cause some debate but after you convince yourself that it is reasonably calibrated - try a mid to small chisel tip (like a T18-D16) with lead free solder and a small to mid size component and see what happens around 660 F and experiment from there with higher and lower temps. With one good chisel, at somewhere around 660 F you should be able to solder a modest through hole component, maybe an 0805 SMD, and some IC legs. From there you can further select tips and temps as needed.

author: BassClef
author_rank: Contributor
timestamp: August 27, 2023, 02:49:29 am
content: My English-unit micrometer and a bit of math says the tip I've been using is 1.6 mm wide. I have several wider tips: 2.4, 3.2 and 5.5 mm. I'll try the 2.4 next time. I've got to replace a failing crystal oven with a TCXO on a Ten Tec Omni VI (mid-1990s ham radio transceiver). I suspect that they still used leaded solder for that. I just want to be sure the Hakko is in reasonable calibration before I mess with that.I also checked to be sure that the unit isn't a clone. Everything that I can see without opening the unit checks out. I bought it through Amazon Prime, the distributor is Kimco Distribution, which Hakko lists as an authorized distributor.I know that you hold the Enter button to change the temperature, and you hold the Up button to enter the ADJustment (calibrate) mode.The good news is that after failing to unsolder the function generator's rotary encoder, I flushed it out with contact cleaner several times. Now it works perfectly. So as long as I can check the Hakko's calibration out by Wednesday (deadline for sending it back), I'm OK.

author: coppercone2
author_rank: Super Contributor
timestamp: August 27, 2023, 03:23:07 am
content: i mean I really wanna know if you came across some kind of crazy non melting solder, put the biggest tip on it and prove that it can melt pleasein the back of my head im thinking some nutjob is laser brazing potentiometers or something

author: IanB
author_rank: Super Contributor
timestamp: August 27, 2023, 03:28:28 am
content: If the iron rapidly melts different kinds of solder on the tip with sizzling flux and wisps of smoke, then the iron is fine.If the solder that won't melt is being used for a mechanical fixture rather than an electrical connection, then it's possible it might be a higher melting point silver solder rather than an ordinary electrical solder. You really should try to melt it using a different iron to see what happens.

author: coppercone2
author_rank: Super Contributor
timestamp: August 27, 2023, 03:30:20 am
content: don't you think someone is a few fries short of a happy meal if they silver soldered a encoder on a chinese function generator?Maybe the cost of aluminum brazing rods was at an all time low. that fits alot better then silver.maybe they were failing to meet the china post package beating standard so they had to up the construction strength

author: bdunham7
author_rank: Super Contributor
timestamp: August 27, 2023, 03:32:05 am
content: Quote from: BassClef on August 27, 2023, 02:49:29 amThey're 100% legit, it's not fake.

author: BassClef
author_rank: Contributor
timestamp: August 27, 2023, 04:21:13 am
content: Hmm, Aluminum (or some other material with a high melting point) for the mechanical connection to the board would explain a lot, wouldn't it? Since the function generator works well now, I don't want to open it up and remove the display board again. If it ain't broke, don't fix it... I don't believe the mechanical connection got even a little tacky at the highest possible iron setting. As I mentioned, when I covered it with molten 60/40 solder at 899 degrees, the solders didn't appear to mix. I wicked away the 60/40, and the same blob was left as before. I with I'd taken photos, but I didn't.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: August 27, 2023, 04:35:41 am
content: Quote from: BassClef on August 27, 2023, 02:49:29 amSmall tips don't work well. They cool off faster than the heating element can put heat back into it. I always go for the biggest bevel tip I can fit into the work area. I've seen others prefer the chisel tip. The conical tips are fairly worthless.See this for a list of tip types:https://www.techspray.com/ultimate-guide-to-electronic-soldering

author: amyk
author_rank: Super Contributor
timestamp: August 27, 2023, 05:09:56 am
content: A layer of oxidation can be surprisingly thermally insulative. Besides what others have mentioned about the heat capacity of the iron, another suggestion is to add flux and scrape the surface of the existing solder with something sharp to break that oxide layer.

author: Veteran68
author_rank: Frequent Contributor
timestamp: August 27, 2023, 03:31:30 pm
content: A large mechanical connection, especially to a large ground plane on the PCB, requires a lot of heat that small tips can't sustain. 1.6mm is a tiny tip for something like that. Use the largest chisel or knife tip you can fit into the area to transfer maximum heat to the joint.

author: Electro Fan
author_rank: Super Contributor
timestamp: August 27, 2023, 04:49:36 pm
content: Quote from: Veteran68 on August 27, 2023, 03:31:30 pm+1

author: coppercone2
author_rank: Super Contributor
timestamp: August 27, 2023, 07:47:04 pm
content: on a side note I feel like a automotive short circuit style iron would take care of everything besides welding.when you have to pull that thing out its like "shit just got real", holding the handle side ways, pointed down and cursing. sometimes two of them. thug life

author: BassClef
author_rank: Contributor
timestamp: August 30, 2023, 08:08:53 am
content: Big thanks to everyone who replied. My FX-888D is fine. I switched to a 2.4 mm chisel tip. It works much better for what I do than the default 1.6 mm tip.The Chinese clone thermometer arrived, and the iron temperatures are what they should be with no recalibration. The clone thermometer also is within 2 degrees C of my Tek DMM probe when tested on a bag of frozen peas and a screwdriver just removed of a boiling water bath.The composition of the solder that wouldn’t melt in my FY-6800 is still a mystery. But since I apparently was able to flush the dirt out of the rotary encoder, I’ll leave well enough alone for now. All advice filed for future use if it acts up again.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: August 30, 2023, 05:57:33 pm
content: It can help to melt some fresh solder to help with the heat transfer. The bevel (and well) tips are good for this. They can hold a bead of solder on them.