Author Topic: EEVblog #242 - Hakko FX-888 Soldering Iron Hack  (Read 23348 times)

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Offline Kozmyk

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EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« on: February 03, 2012, 02:15:36 pm »
Really enjoyed #242.
Simple and to the point plus a bit of investigation when the unexpected arose.
A good bit of practical hakking ...
Great!
 

Offline TerminalJack505

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #1 on: February 03, 2012, 02:54:27 pm »
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.
 

Offline IanB

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #2 on: February 03, 2012, 03:00:28 pm »
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.
I'm not an EE--what am I doing here?
 

Offline EEVblog

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #3 on: February 03, 2012, 03:05:06 pm »
Really enjoyed #242.
Simple and to the point

My videos are never to the point  :P

Dave.
 

Offline EEVblog

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #4 on: February 03, 2012, 03:07:17 pm »
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 wonder what the variability between units is on the hysteresis for the heater and subsequently LED on/off ratio?

Dave.
 

Offline Rufus

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #5 on: February 03, 2012, 03:15:09 pm »
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.
 

Offline Kozmyk

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #6 on: February 03, 2012, 04:19:05 pm »
Really enjoyed #242.
Simple and to the point

My videos are never to the point  :P

Dave.
I stand corrected.
You digress ...  ::)
 

Offline vk6zgo

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #7 on: February 03, 2012, 05:08:09 pm »
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! :D

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
 

Offline timelessbeing

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #8 on: February 03, 2012, 09:14:24 pm »
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 way :)
By 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 now :(

I would really like to see the teardown Dave did. Does anybody know which episode that was?
 

Offline EEVblog

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #9 on: February 03, 2012, 09:25:09 pm »
I would really like to see the teardown Dave did. Does anybody know which episode that was?

It was a live show, and was pretty lame if I recall  ;D

Dave.
 

Offline harnon

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #10 on: February 03, 2012, 09:42:51 pm »
I also enjoyed this episode.  For a beginner its good to have these kinds of design examples, it gets me thinking! Thanks!
 

Offline fmaimon

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #11 on: February 04, 2012, 12:50:17 am »
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.
 

Offline siliconmix

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #12 on: February 04, 2012, 07:50:40 am »
nice effective hack.first time i've heard "hot snot" before  :)
 

Offline ivan747

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #13 on: February 04, 2012, 11:41:41 am »
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.

A 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.
Nothing like the smell of rosin core solder in the morning.
"Could you not use some of that crowdfunded $1.5 million to hire a graphic designer who understands perspective?" -Delta
"A soldering station I bought once had a sticker on it that said, I shit you not, 'QENUINE'." -c4757p
 

Offline ivan747

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #14 on: February 04, 2012, 11:50:49 am »
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.
Nothing like the smell of rosin core solder in the morning.
"Could you not use some of that crowdfunded $1.5 million to hire a graphic designer who understands perspective?" -Delta
"A soldering station I bought once had a sticker on it that said, I shit you not, 'QENUINE'." -c4757p
 

Offline gregariz

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #15 on: February 04, 2012, 12:03:55 pm »
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.

I 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.
 

Offline PeteInTexas

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #16 on: February 04, 2012, 01:52:05 pm »
Great episode.  I liked it.  Glad I tuned in.  And new one for my lexicon: "pwm-ing".  :D
 

Offline Clayton

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #17 on: February 05, 2012, 01:21:18 pm »
I'm honored; Dave has done pretty much what I came up with a while aback @ Post #6
http://www.eevblog.com/forum/projects-designs-and-technical-stuff/add-a-power-indicator-to-the-fx888-soldering-station-help-needed/?topicseen

What do they say about great minds thinking alike?  ;D
Anyways good job Dave!
 

Offline TerminalJack505

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #18 on: February 05, 2012, 02:34:44 pm »
I'm honored; Dave has done pretty much what I came up with a while aback @ Post #6
http://www.eevblog.com/forum/projects-designs-and-technical-stuff/add-a-power-indicator-to-the-fx888-soldering-station-help-needed/?topicseen

What do they say about great minds thinking alike?  ;D
Anyways good job Dave!

The 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.
 

Offline TerminalJack505

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #19 on: February 06, 2012, 12:07:22 am »
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!   ;D

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.
 

Offline amspire

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #20 on: February 06, 2012, 12:22:21 pm »
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.

 

Offline SgtRock

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #21 on: February 07, 2012, 06:22:30 am »
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 1616

Best Regards
Clear Ether
« Last Edit: February 08, 2012, 03:23:27 am by SgtRock »
 

Offline TerminalJack505

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #22 on: February 07, 2012, 12:57:58 pm »
Greetings EEVBees:

--So Dave has a solution to for the lack of and "on light" for the Hakkos, that does not 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 1616

Best Regards
Clear Ether

LOL.

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.
 

Offline amspire

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #23 on: February 07, 2012, 01:17:16 pm »
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. 

Tom'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.
 

Offline TerminalJack505

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Re: EEVblog #242 - Hakko FX-888 Soldering Iron Hack
« Reply #24 on: February 07, 2012, 01:31:47 pm »
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. 

Tom'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.

Great!  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.)
 


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