Help w/ Hakko 888D and Tip Temp Sensor/Calibration? I screwed up :'( - Page 1
Forum section: electronics / beginners

author: MyHeadHz
author_rank: Regular Contributor
timestamp: October 02, 2017, 06:30:23 am
content: I have a Hakko 888D (new, digital version of the original 888 soldering iron), but I screwed up the temperature calibration. Can someone with a Hakko 888D and a soldering tip temperature tester repeat my mistakes/steps (below) and then test to help me get back into approximate calibration please? Unfortunately, I don't have access to a temperature testing/calibration unit.Explanation about how I screwed it up and my train of thought (shorter version is in the next paragraph): I needed a bit more heat (was set at 630F), so I set the temp to 730 (I thought) but the tip got colder. Apparently I hit the buttons in the wrong order and changedcalibrationsetting instead oftemperaturesetting (many of the same buttons are reused for both operations!) So apparently the new "630" temperature (it showed 730 when I "recalibrated" it, then cooled to the new "630") is about 100F cooler (guess) than the calibrated 630. In other words, 630F is probably more like ~530F. So after it got to temp on the new "630," I "calibrated" it again, setting it to "530. " My logic was that I would just put it about 100F in the opposite direction and it's back to calibration. After doing this, I realized that ( for a few reasons) it actually may or may not "undo" what I did as I had planned...Shorter version (commands to unit): 1. Iron set to (factory calibrated) 630F desired temperature and stabilized. 2. Set Calibration to "730" and waited for it to stabilize (cool down) to set temperature of "630". 3. Set calibration to "530" and waited for it to stabilize (heat up) to the set temp of "630".Can someone please repeat those steps and test it to see what it reads when set to 630F? If my logic is correct and someone follows those steps, I should be able to set the calibration to that measured temp and be close enough to my actual temperature for my purposes.I hate the "simplified" interface of the 888D. It is annoying and confusing to use. I wish I would have just taken the time to find a NOS or used analog 888 instead.

author: KL27x
author_rank: Super Contributor
timestamp: October 02, 2017, 07:59:42 am
content: If you have some lead solder, turn the temp down to 120C. The turn it up 5 degrees at a time until it can melt solder. Then go into calibration mode and set it to 185C. This is as close as you really need. You can buy temp probe if you want, but temp will change a little bit depending on tip shape and you will have to recalibrate if you ever change the heater/handpiece.

author: Ian.M
author_rank: Super Contributor
timestamp: October 02, 2017, 08:25:46 am
content: *ANY* Eutectic solder*can be used for calibration provided you know its melting point, it doesn't have to be Sn63/Pb37. If you need greater accuracy, once you've found the rough melting point as suggested by KL27x, clean off the tip, then with a generous blob of fresh solder on the tip work downwards a degree at a time, stirring it with a wooden toothpick to detect when it solidifies.* Common Sn60/Pb40 solder is near-eutectic with about a 5 deg C melting point range. 185 deg C is roughly in the middle. Pb-free: SAC305 (Sn/Ag3.0/Cu0.5) is also near eutectic with a narrower melting point range around 218 deg C, and SAC407 (Sn/Ag4.0/Cu0.7) is eutectic with a melting point of 217 deg C

author: KL27x
author_rank: Super Contributor
timestamp: October 02, 2017, 08:59:10 am
content: The 888D goes down to 50C. So you could use also calibrate it by boiling a little drop of water.Or course, the working area of the iron is going to be 300-375ish. Better to calibrate it closest to there, as possible.Factory reset, yeah. I think calibrating with solder will end up closer than a reset. I have owned 4 of these things, and the out-of-box accuracy has spread of maybe 20C between different station-heater pairs. And that's in my small sample size of 4 units. I'm pretty sure factory reset just puts it to a default that was never tuned to the specific heater it shipped with.

author: wraper
author_rank: Unknown
timestamp: October 02, 2017, 09:17:57 am
content: Quote from: KL27x on October 02, 2017, 08:59:10 amYou won't be able to calibrate with water, it's not like it starts to exaporate at exactly at 100oC. As well as you won't be able to reliably calibrate it with solder. Piece of solder will be colder than tip and it will be very difficult to catch exact melting moment. On the other hand you can stick thermocouple into a molten solder blob which will give decent thermal transfer. Thermocouple must have very low thermal mass, otherwise measurment won't be correct.

author: KL27x
author_rank: Super Contributor
timestamp: October 02, 2017, 10:49:46 am
content: QuoteEvaporate != boil. If water vapor forms inside the drop, you will see bubbles.QuoteAll you have to do is wait a whole ten seconds to see if it melts. Increase the temp a bit and repeat.Maybe I should also suggest you use the smallest piece of solderwire you have, and not a 1kg bar. It's the heatsinking that matters, not the initial temp of the solder. It could be -100C to begin with, you just have to wait. The iron is thermostatically controlled. It is designed to heat things that are cold.I dunno what you think is so magical about the factory default. It's not calibrated all that great from the factory. The micro probably has a greatly accurate data table in it. Carefully tuned to be accurate if the ADC, clock/resonator, Vdd/voltage reference, heater, thermistor, opamps and opamp resistors all happen to fall into the middle of the bell curve. But it don't really mean anything to an individual iron. I suppose it's possible that someone at Hakko calibrates each station with the handpiece it ships with. And that this value is stored in EEPROM. And that it isn't overwritten with a generic default on a reset. But I'd bet $10,000.00 that's not the case.That anyone should anyone feel like they can't calibrate an iron to work the way they want it to at LEAST as well as however it came out of the box makes me want to. I'm picturing the inventor of the sundial explaining it to another caveman. "But how do you know what time it REALLY is?"

author: MyHeadHz
author_rank: Regular Contributor
timestamp: October 02, 2017, 02:03:58 pm
content: I had assumed that there was a calibration process at the factory. The comments here gave me some doubt, so I read around. I couldn't find a direct statement on the matter, but theHakko 888D Instruction Manualstrongly implies that there is no such manual calibration step. So the suggestions to just reset the device will bring me back to exactly what I had from the factory (which should be within +/- 15F). That's good enough for me!Thanks for the help everyone.

author: Ian.M
author_rank: Super Contributor
timestamp: October 02, 2017, 02:55:45 pm
content: That's really not a very helpful link. Try:http://www.be-electronics.com/v/vspfiles/productTips/FX888DSettingsAndAdjustmentsSimplified.pdf

author: amyk
author_rank: Super Contributor
timestamp: October 03, 2017, 12:30:46 am
content: orhttps://www.eevblog.com/forum/testgear/fake-$10-hakko-fg100-iron-thermometer/Also,https://www.aliexpress.com/store/product/For-HAKKO-FX-888-Digital-Thermostat-soldering-iron-station-control-board/1756394_32531034107.htmlif you want to give your station an "analogue upgrade".