EEVblog #242 - Hakko FX-888 Soldering Iron Hack - Page 1
Forum section: electronics / general

author: Kozmyk
author_rank: Regular Contributor
timestamp: February 03, 2012, 03:15:36 am
content: Really enjoyed #242.Simple and to the point plus a bit of investigation when the unexpected arose.A good bit of practical hakking ...Great!

author: TerminalJack505
author_rank: Super Contributor
timestamp: February 03, 2012, 03:54:27 am
content: Yep. I thought this was a really good episode that those just starting in electronics would find interesting. Dave went through the basics of working through an issue and touched on BJT and MOSFET transistors and LEDs.I thought my Hakko 936 shut itself down automatically after 2 hours. Apparently it doesn't. Not sure why I got the impression that it does but now I'm thinking about hacking it.I'll probably go the microcontroller route and have it sound a subtle little click via piezo buzzer every 10 minutes and have it sound a more annoying tone once an hour. This should work better for me than hacking the LED like Dave did since I actually can't easily see the LED as it is now. The station is somewhat obscured by the boom on my microscope.

author: IanB
author_rank: Super Contributor
timestamp: February 03, 2012, 04:00:28 am
content: Where my FX-888 sits on my bench I can hear it very clearly as it switches on and off--"brrrmm...silence....brrrrm...silence...."--and also the red LED switches on and off quite frequently when the iron is in the stand so it is hard to miss that it is switched on. I do in any case unplug everything when I leave, so leaving things switched on is not much of a worry. Although I don't have one in my work area, a big master switch for all the power rails on the bench would probably be a neat idea.

author: EEVblog
author_rank: Unknown
timestamp: February 03, 2012, 04:05:06 am
content: Quote from: Kozmyk on February 03, 2012, 03:15:36 amMy videos are never to the pointDave.

author: EEVblog
author_rank: Unknown
timestamp: February 03, 2012, 04:07:17 am
content: Quote from: IanB on February 03, 2012, 04:00:28 amI wonder what the variability between units is on the hysteresis for the heater and subsequently LED on/off ratio?Dave.

author: Rufus
author_rank: Super Contributor
timestamp: February 03, 2012, 04:15:09 am
content: Think I would have just stuck a 10k across the open collector and settled for bright and dim, works when you are color blind too.Or maybe something lower and settled for bright and not so bright, the flashing light isn't much use anyway.

author: Kozmyk
author_rank: Regular Contributor
timestamp: February 03, 2012, 05:19:05 am
content: Quote from: EEVblog on February 03, 2012, 04:05:06 amI stand corrected.You digress ...

author: vk6zgo
author_rank: Super Contributor
timestamp: February 03, 2012, 06:08:09 am
content: Weller WTCPs have gone cheap to the extent that they don't have the red neon "on" lamp in the switch anymore.You're supposed to know by the switch position.Luckily,I've got one of the old ones!The problem with the WTCP is that the magnetic switch fails & the iron overheats.If you listen closely,you can hear it click when it's working,but a light would be nice.Problem is,the rotten things run the element on AC & the switch is in the handset,so none of the easy answers work.Even if I bought a Hakko,I'd still want to keep the Weller,so I might have to work out a way of incorporating a "heating" light.VK6ZGO

author: timelessbeing
author_rank: Frequent Contributor
timestamp: February 03, 2012, 10:14:24 am
content: I agree with Dave about the design of my "triple-8". Just because the work is boring, your tools don't have to look that wayBy the way, what is temperature knob used for? Isn't soldering usually done @ 350deg, with the iron adjusting output to maintain that temperature? I decided to calibrate the iron myself using my multimeter temp probe, but then I was told doing it that way is pants, so maybe it's buggered nowI would really like to see the teardown Dave did. Does anybody know which episode that was?

author: EEVblog
author_rank: Unknown
timestamp: February 03, 2012, 10:25:09 am
content: Quote from: timelessbeing on February 03, 2012, 10:14:24 amIt was a live show, and was pretty lame if I recallDave.

author: harnon
author_rank: Regular Contributor
timestamp: February 03, 2012, 10:42:51 am
content: I also enjoyed this episode. For a beginner its good to have these kinds of design examples, it gets me thinking! Thanks!

author: fmaimon
author_rank: Unknown
timestamp: February 03, 2012, 01:50:17 pm
content: Is the 2V across the green led high enough for the Vgson of any mosfet? In the other hand, it's creating a negative feedback in the mosfet, so it maintain 2V between the gate and the drain, so the Vds + Vdiode is enough to turn the mosfet on.

author: siliconmix
author_rank: Frequent Contributor
timestamp: February 03, 2012, 08:50:40 pm
content: nice effective hack.first time i've heard "hot snot" before

author: ivan747
author_rank: Super Contributor
timestamp: February 04, 2012, 12:41:41 am
content: Quote from: IanB on February 03, 2012, 04:00:28 amA big red master emergency kill switch is a neat idea. Personally, I just turn off the power strip. When dealing with mains, I have one on the floor so I can switch it off with one foot in case something goes wrong.

author: ivan747
author_rank: Super Contributor
timestamp: February 04, 2012, 12:50:49 am
content: After watching the video, I breadboarded a simpler solution based on MikesElectricStuff suggestion. I connected a 4k7 resistor between the cathode of the LED and ground. Tested it at 9V and it lights the LED enough to be seen. When I simulate the open collector being switched on, the LED lights up more as expected.There's not much difference in perceivable light output between 5mA and 20mA (4x more) but you can definitely see the difference between 5mA and 2.5mA (2x difference). It's a combination of the non-linearity of human senses and the non-linearity of the LED light output vs. forward current curve.Dave, based on what I saw on your video, I think there is a big difference in hysteresis between units. Mine lights up consistently every 3-5 seconds for 1 second. I don't know what might cause it though.

author: gregariz
author_rank: Frequent Contributor
timestamp: February 04, 2012, 01:03:55 am
content: Quote from: IanB on February 03, 2012, 04:00:28 amI cant reach the lights which are wired into the bench power so the only way to turn them off is to turn the main switch off.

author: PeteInTexas
author_rank: Frequent Contributor
timestamp: February 04, 2012, 02:52:05 am
content: Great episode. I liked it. Glad I tuned in. And new one for my lexicon: "pwm-ing".

author: Clayton
author_rank: Contributor
timestamp: February 05, 2012, 02:21:18 am
content: I'm honored; Dave has done pretty much what I came up with a while aback @ Post #6https://www.eevblog.com/forum/projects-designs-and-technical-stuff/add-a-power-indicator-to-the-fx888-soldering-station-help-needed/?topicseenWhat do they say about great minds thinking alike?Anyways good job Dave!

author: TerminalJack505
author_rank: Super Contributor
timestamp: February 05, 2012, 03:34:44 am
content: Quote from: Clayton on February 05, 2012, 02:21:18 amThe schematic for the Hakko 936 referenced in that thread has been a real boon for me the last couple of days since I'm thinking about hacking my 936. Props to the gentleman (Tom Hammond) that produced it.So far, from what I can tell, his schematic has been spot-on with just one exception. The schematic shows the 5.1V zener diode (ZD2) backward. It's fairly obvious that it's backward in the schematic but I can confirm from the actual board that it is.I started out just wanting to hack the 936 so that I could sound a tone every now and then to remind me that the station was on but after finding the schematic I think I can add an auto-shutdown feature pretty easily.I don't know if I want to mess with the LED or not but I might either add a power indicator LED or do something like Dave did with his 888 with a bi-color LED.I'll create a new thread and post a schematic of my hack here in the next couple of days in case anyone is interested.

author: TerminalJack505
author_rank: Super Contributor
timestamp: February 05, 2012, 01:07:22 pm
content: Ah, the irony!I've been working on my own hack for my Hakko 936. Doing an LED hack like Dave's on a 936 requires the handset socket to be de-soldered just to get the faceplate and the PCB separated so that the LED can be accessed. Because of this and since I can't easily see the LED anyway (my bench top is seriously cluttered), I wasn't going to bother with an LED hack.Call it feature creep or whatever but I changed my mind. Heck, I had one whole pin not doing anything on my microcontroller!One of the restrictions that I've put on myself for this particular project is that I'm going to only use parts that I have on-hand. So when I went looking for an LED to use, guess what I found? Yep, you guessed it: a red/green bi-color common anode 5mm LED--12 of them actually. Yep, the exact LED Dave was looking for. I bought them from one of those clearance sites so there's no telling what the story is with them.To add to the irony, like I said, I need to drive the LEDs using the last remaining pin on my MCU. Which basically means I need a circuit nearly identical to the one Dave showed in his video. LOL.So thank you very much Mr. Dave Jones.By the way, the LED in my hack isn't going to replace the normal heater indicator LED. I'm going to drill a hole in the panel and the LED is going to be a power indicator. I'll use green for normal operation and probably make the LED blink red when my circuit shuts the station down. (Or maybe I'll use yellow so that the LED isn't confused with the heater LED.)If you still need some of those LEDs, Dave, let me know. I'll drop them in an envelope and send them your way.

author: amspire
author_rank: Super Contributor
timestamp: February 06, 2012, 01:22:21 am
content: Dave inspired me to fix up my Hakko 936 last night as well. I decided to add the second green LED as I had a bag of them handy, and it is easy to do on a 936.

author: SgtRock
author_rank: Unknown
timestamp: February 06, 2012, 07:22:30 pm
content: Greetings EEVBees:--So Dave has a solution to for the lack of and "on light" for the Hakkos, that does not require a hole to be drilled. Very elegant, but.--Nowwww he tells me!!! Feh!"If it were done when 'tis done, then t'were well. It were done quickly."William Shakespeare 1564 1616Best RegardsClear Ether

author: TerminalJack505
author_rank: Super Contributor
timestamp: February 07, 2012, 01:57:58 am
content: Quote from: SgtRock on February 06, 2012, 07:22:30 pmLOL.Did you (or anyone else out there that happens to be reading this) use Tom Hammond's Hakko 936 power indicator hack?Tom is the gentleman that produced a schematic for the 936. You can find his power indicator hack in the same document as the schematic. His web page is the first hit if you Google "hakko 936 schematic."I'm curious if this is what you based your hack on because, from what I can tell, his document is wrong. He shows the power indicator LED and current-limiting resistor running parallel to the rectifier diode (D3.) Obviously, this shouldn't work but since his document is so detailed and well-put together I have to wonder if I'm just missing something.I'm pretty sure he meant to use the PCB trace just north of the one shown in his document for the positive voltage side of his hack. This trace is VCC, per his document. This would put the LED and resistor parallel to the 220 uF cap (C1) and provide 33V rectified DC (and this would explain the beefy 1W limiting resistor he uses.)I'm going to do a similar hack and looked to see what he had done with regard to the LED and would do something similar since, in theory, his hack would be 'proven.' At one point I was going to power the LED from the ~9.5V between VCC and "CKT GND" but decided not to since that current would then be returning through the zener providing the VEE voltage as well as R1, which has already got 50 mA going through it and dropping 18V. It's a 2W resistor but I figured I wouldn't mess with that part of the circuit if I didn't have to.

author: amspire
author_rank: Super Contributor
timestamp: February 07, 2012, 02:17:16 am
content: Quote from: TerminalJack505 on February 07, 2012, 01:57:58 amTom's hack works but I don't like it. It is like turning a diode into a leaky diode.I did the mod, but instead of following Tom's circuit, I put the green LED and a 8K2 resistor across the 220uF capacitor, which will probably add about 1V ripple to the capacitor. If you don't want to risk the extra ripple, just put a diode and a 3K9 in series with the LED and put it across the transformer windings. If you orient it in the reverse direction to the circuit rectifier diode, it will help reduce the DC current from the transformer, so it will be very slightly happier.Richard.

author: TerminalJack505
author_rank: Super Contributor
timestamp: February 07, 2012, 02:31:47 am
content: Quote from: amspire on February 07, 2012, 02:17:16 amGreat! Thanks for the information. I hadn't thought about the added ripple. I'll have to keep that in mind since some of that ripple is going to be seen on VCC, which is used for the op amps and the triac driver. (VCC happens to be the triac driver's GND since it operates at -9V.)

author: ModemHead
author_rank: Frequent Contributor
timestamp: February 07, 2012, 04:13:02 am
content: I added an LED to mine as well, but I put it between ground and VEE, which is the -5V supply for the op-amps. The F1 location was unused, so I put the 330R ballast resistor there.

author: TerminalJack505
author_rank: Super Contributor
timestamp: February 07, 2012, 04:40:58 am
content: Quote from: ModemHead on February 07, 2012, 04:13:02 amNice! I like how you put the F1 spot to use there.

author: LEECH666
author_rank: Frequent Contributor
timestamp: February 09, 2012, 07:08:07 am
content: Hehe, nice video Dave.OT:"Sadly" all the four irons I own at the moment don't suffer from this issue. So no need to hack them, although I have to add that three out of the four irons play, or used to play, in a different league regarding the pricetag.My irons are:Weller WECP-20:Has a neon lamp switch and also a LED that lights up steadily when heating and keeps blinking once the target temperature is reached.Weller WSD-81:Digital temperature readout.Atten 858D+:Digital temperature readout.Pace MBT-250:Digital temperature readout.I think I am excessively well equipped regarding soldering irons.Now that I got the MBT-250 (which also came with a hot air handpiece) I might as well sell the 858D+ and WECP-20 to free up some space on my workbench.Cheers from Germany,Florian

author: timorousme
author_rank: Contributor
timestamp: February 09, 2012, 05:39:33 pm
content: Definitely a cool video. It's not something that I'm going to do with my FX-888, but pretty useful nonetheless for projects in which that could be implemented.

author: EEVblog
author_rank: Unknown
timestamp: February 13, 2012, 08:21:55 am
content: Quote from: timorousme on February 09, 2012, 05:39:33 pmYeah, that was the idea. Can be used in many other apps too.Dave.

author: dcel
author_rank: Regular Contributor
timestamp: February 17, 2012, 12:18:24 pm
content: I ordered one from fry's sunday night and showed up today ( I work nights ) and used it for about two hours and ordered another one at 1 AM. These things are great.I like the mod and plan to "fix" the problem on both, just I though why not keep with the color scheme and use a blue and yellow "chip" LEDs in one of those light pipes. Blue power on and Yellow heating, should look cool.Thanks guys for the tip about them on sale at Fry's, now I'll have two in less than a week, and for cheap!Chris

author: The_Penguin
author_rank: Regular Contributor
timestamp: February 23, 2012, 02:58:09 am
content: Quote from: amspire on February 07, 2012, 02:17:16 amOk, I just *have* to ask!Is this a "UK" thing? I'm Canadian and have been doing hobbyist electronics for a long time. Not since hanging out here have I seen this "8K2 2K2" stuff. I'm assuming this means 8.2 kilohms? We just say 8.2K here.Not criticizing, just curious.I won't get into Aluminum vs. Aluminium...

author: IanB
author_rank: Super Contributor
timestamp: February 23, 2012, 03:04:02 am
content: Quote from: The_Penguin on February 23, 2012, 02:58:09 amNo, no, no, no, no!!8.2 K is 8.2 kelvin (very cold). You may not like the inconsistency with M and G and T and whatever, but "kilo" is "k" (lower case). 8.2 kilohms is 8.2 k.As for the 8k2 thing, this is a notation to avoid errors on markings and diagrams. If someone wrote "8.2k" and the "." got lost or erased due to poor ink or abrasion, it might get confused with 82k. Thus to avoid Mars probes going off course a convention has been adopted to write 8k2 and make it very clear where the decimal point goes. Similarly you could write 8R2 for 8.2 ohms or 8M2 for 8.2 megohms. Or even 4u7 for 4.7 microfarads.

author: The_Penguin
author_rank: Regular Contributor
timestamp: February 23, 2012, 03:19:01 am
content: Quote from: IanB on February 23, 2012, 03:04:02 amI DID say I was Canadian...Thanks for the enlightenment.

author: timorousme
author_rank: Contributor
timestamp: February 24, 2012, 03:41:32 pm
content: Quote from: IanB on February 23, 2012, 03:04:02 amI've actually done this MYSELF on MY OWN DESIGNS. I spent forever trying to figure out what was wrong, checking every little thing over and over again, and then eventually noticed the decimal. I now stick to the 8k2 notation.

author: markman
author_rank: Contributor
timestamp: April 28, 2012, 05:48:21 am
content: I've thought about modifying my Hakko 936-9 about a thousand times because I've left it powered on for more than a day before. I went looking for a schematic and layout and stumbled back on here. The schematic and layout from Tom Hammond, N0SS, helped a lot. I also found Radio Shack in the US carries a 3 color LED with a common anode that makes a red/green (or red/blue, etc.) a piece of cake. It's a bit brighter than the original as well. One FET and one 1.8K resistor and it was done. Glad I finally did it.There was also a 100K resistor (R13) going from the same point that drives the original resistor & LED that appears to generate the hysteresis for the temperature control. I probably threw the temperature calibration off slightly, but I changed it to a 1Meg and the iron cycles much faster now. I really doubt it improves the thermal regulation much, but when the iron is sitting unloaded, it blinks about once per second instead of once every several seconds and obviously the "on" time is much shorter as well. I also notice that when the iron is warming up and reaches temperature, there must be a little overshoot of the actual iron tip because there is a few second pause before it starts the normal blinking that didn't seem so obvious before.

author: saturation
author_rank: Super Contributor
timestamp: May 07, 2012, 02:15:56 pm
content: You could also simply replace the ON/OFF switch a with a neon lit switch, its the easiest mod to do.

author: John203
author_rank: Newbie
timestamp: August 03, 2012, 03:03:08 pm
content: I have a question about the transformer of the Hakko FX-888.Can anybody tell me if the transformer also have leads for 220V?I am living in The Netherlands and a 220V version of the FX-888 is impossible to buy.So I was thinking maybe it is just a matter to use the 220V leads if present.

author: IanB
author_rank: Super Contributor
timestamp: August 03, 2012, 03:09:21 pm
content: Quote from: John203 on August 03, 2012, 03:03:08 pmNo, the 120 V version of the FX-888 cannot be converted to 220/230/240 V operation. However, it can be powered from an external 120 V transformer.

author: John203
author_rank: Newbie
timestamp: August 03, 2012, 03:33:11 pm
content: Quote from: IanB on August 03, 2012, 03:09:21 pmThanks IanB for this information.I will take your suggestion of an external 120V transformer in consideration.

author: GraphicArmy
author_rank: Newbie
timestamp: August 14, 2012, 03:54:28 am
content: Can someone please post a "Parts List" for this project?thanks

author: dcel
author_rank: Regular Contributor
timestamp: August 15, 2012, 11:34:35 am
content: Have you watched Daves video about the hack? All the info you need is in there.Chris

author: rodcastler
author_rank: Regular Contributor
timestamp: January 05, 2013, 02:44:44 pm
content: Has anyone done the LED mod on the 220v version (the one with op amps instead of a microcontroller)?I could find a 10v line from the big capacitor, but the LED terminal toggles between 34.5V and 12v so Dave's circuit won't work.thoughts?

author: rodcastler
author_rank: Regular Contributor
timestamp: January 05, 2013, 04:39:02 pm
content: I ended up throwing an optocoupler at the LED interface and switch the base of the transistor through that. works like charm.http://rodelectronics.blogspot.com/2012/12/hakko-fx-888-220v-version-led-mod.html

author: torch
author_rank: Frequent Contributor
timestamp: January 08, 2013, 02:30:11 pm
content: Quote from: EEVblog on February 03, 2012, 04:07:17 amI got one today and mine is cycling 10x in 30 seconds @ 350°C. I'm not sure that alternating colours would actually be more eye-catching than the slow flash. Now, mounting a flashing LED ontopof the unit...

author: rodcastler
author_rank: Regular Contributor
timestamp: January 15, 2013, 04:24:57 pm
content: As Dave says, "Murphy will get you": I mean, this mod is a must-do! and it justified its existence within the first week when I left it on and there it was: the green LED instead of a turned off LED.The LED on top of the unit will also serve the purpose, but possibly ruin the design.

author: rodcastler
author_rank: Regular Contributor
timestamp: March 11, 2013, 07:24:53 pm
content: Does anybody know if the 220V version without a microcontroller was a fake in the end?Mine works pretty well, but I want to know the truth!!

author: basman
author_rank: Newbie
timestamp: May 28, 2013, 08:21:06 pm
content: I got a 220V version of the FX-888 from aliexpress recently. Inspired by Dave's video I ran to a local store and bought a dual colour LED. However, back home I realized it was a different type than that used by Dave.Darn, I am such a bloody beginner, I did not even realize there could be different types!My red/green LED has a common cathode. So I had to re-invent the whole boodle. Sorry, it's done with bipolars. But hey, I got it working. My first mod ever and it became a success once I fiddled a couple of stripes of rubber tape in between some of the legs of the messy flying composition.I was so happy, I really wish everyone interested in electronics can have such a blast once in a while.In contrary to the specimen hacked in the video, my FX-888 does not have a 9V PWM signal on the original LED, but 16V with a bit of a ripple on top. So I dropped the caps and threw in an extra transistor.Hope this helps you in doing your own hack. Keep it frizzling!

author: rodcastler
author_rank: Regular Contributor
timestamp: October 07, 2013, 09:41:09 pm
content: Your design shows an IC with an open collector present in the 220V version. I haven't seen any of those with a micro controller. Can you post a photo of your board? That would help others to differentiate among the real and fake ones. Also, where did you get it from? Cheers...

author: Greyersting
author_rank: Regular Contributor
timestamp: October 09, 2013, 11:31:58 pm
content: What soldering iron does Dave use personally?

author: beatgr
author_rank: Newbie
timestamp: August 04, 2014, 06:05:38 pm
content: Tom Hammond, N0SS passed away (cancer) on August 4, 2011.He first reverse engineered the PC board layout and produced a schematic diagramusing CorelDraw for his Hakko 936-9 soldering station in the late 1990s.He revised this Hakko 936 schematic and board layout, from positive feedback by anumber of builder sources. His last revision was 1.7 (March 26, 2011).http://www.mmccs.com/mmarc/n0ss/hakko_936_schem-pcb_%26_mod_v1r7.pdfI think he would be happy to know that his work has been useful to the Maker community.g. beatw9gb

author: basman
author_rank: Newbie
timestamp: January 08, 2017, 08:59:43 am
content: @rodcastler: I did not dare to open the case to make a photo due to the flying composition. Since the hack, it still works fine after 4 years.You can identify the heating regulator's output easily with Dave's video or by following the connections of the original LED. Then have a look at the signal using your oscilloscope.If you see PWM signal, it's a microcontroller. Otherwize, if the LED receives a constant voltage level while it is on, you got the opamp version, like I did.