Fixing a common fault with the 936D style solder stations.

The very common Hakko-themed digital soldering stations seem to have a common fault that causes a sensor error (S-E), erroneous temperature readings and failure to reliably heat the iron.
These are all down to a very simple design fault, where the front panel and PCB are connected by the solder pads on the soldering iron connector. It appears that the solder connections and PCB pads at that stress point can crack.
Here's how to fix the issue permanently and get your iron working properly.

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[grendelum]

Back in the day when I fixed TVs for a living, a certain manufacturer did something similar by connecting the button panel circuit board *with one screw on the **_opposite end_** of the power button !!!* I did this exact same fix dozens of times, good to see that old mistakes never go out of style...

[retrocomputeruser]

Hi Clive my fist comment here (and rather late). I bought one of the plain black 936D's with red buttons and trim pot calibration. Mine was so far out of calibration that the trimmer wouldn't adjust it. I think it was still about 20 deg too high on full adjustment. I ended up swapping a resistor on the pcb. Now it calibrates about half way on the trim pot. I also used a Hakko 191 knock off sensor like you have. The 936 type units look stackable to me.

I also have a 898D+ (similar to your other station with a heat gun) but the irons are not compatible as the 898D+ uses the thermistor and the 936D uses the thermocouple type elements. Also I had to change the polarity of the thermocouple wires on a spare iron for that to work for some reason. Love your uploads and I've still loads to watch. Subbed.

[KeanM]

Soldering stations that haven't been soldered together properly. How ironic!

[MGBGT]

Thanks a million Clive. I purchased 936D a few months ago and it never worked from Day One (Temp reading just remained at 30 and Iron never heated up). In fairness the Seller did supply a new unit (which works fine) but he allowed me to keep the faulty one. After following your instructions it now works perfectly.

[hairypaulmmwab]

I have a WLX-936D that worked fine for a few months then one day just failed to power up. On investigation I found the soldering on the board was good, all connections and components checked out fine. I was amazed to discover the mains power cable was not passing power into the unit! On looking closer at the mains cable it was marked up as '3CX0.75mm but only had a few very thin strands of copper. Even attempting to strip the insulation snapped the conductors. Fitted proper mains cable and the unit has worked perfectly ever since. The naff cable had 6 strands in Earth conductor, and only 4 in the Neutral and 3 in the Live.. Lesson learned, check and replace power cable on ALL cheapo products, not just the dodgy 'sleeved pin' plugs..

[eLuke]

Great fix, but I'd make one change to further improve it. I'd use solder wick instead of solid core wire. The solder wick conducts with low resistance (like the wire) but remains flexible (providing you don't fill the entire length of it with solder). It's easier to use than multi-strand wire as you don't need to deal with insulation or the strands unraveling.

I've done this on heaps of handheld radios where the RF connector center pin was soldered direct or with solid copper wire onto the PCB and there was enough flex after a few years for the connector center pin to eventually break the solder joint. That extra flex in the solder wick solved that problem.

Cheers
Luke

[ianide]

Been using a Weller EC1002 for somewhere near 10+ years. Oddly enough it has never needed a fix. Thanks for the cool videos Clive

[NotRealNamesAgain]

Soldering station's down. Thanks to Big Clive, I know how to fix it. I'll just get my solde- oh.

[experiencingtechnicaldiffi]

I have purchased a 898D+ reflow station which is basically that iron, a hot air gun and some accessories. After an exciting episode of unboxing and admiring my purchase I figured I should test and adjust it. The air gun worked really well and could be adjusted to burn or not burn my fingers with ease. The iron also works quite well and so I adjusted it for temp by starting at 200°C and raising it by 10° increments until it would melt tin solder easily and then adding another 10°C. That way I am assured it will have the temp and thermal capacity to solder all but the biggest power connections without the tendency to lift tracks or let out the smoke from even the smallest diodes.
 Then I thought "you (meaning me) should check and see if the tip is grounded, just to be thorough". Imagine my surprise when it weren't! OH NO! I had already waited long enough to get this thing what with one seller absconding with my money and having to file a claim with ebay, wait for a refund and then order it from someone else. US sellers, but still it took longer than if I had bought it from "the peoples republic". I was not about to wait for a replacement. Besides, I had grown attached to it, what with the burns on my fingers and oodles of admiration already bestowed (see above). So it was determined I was to investigate.
 I disconnected the iron and using a meter I measured the connections to find out what was what. Everything checked out fine so I moved on. Measuring the connector on the case I found no ground for the iron but the hot air gun was grounded. Upon opening the case I discovered I still can't see shit without a loupe so back into the house I go. Besides, I needed more coffee and to scratch my... well, you know.
 A quick study of the internals revealed that the well attached ground wire wasn't attached to the ground plane of the board, just screwed through to the front case and the hot air gun. The iron ground connection was jumpered to the board, however the resistor that was supposed to connect to the ground plane was not there as marked on the board. It may have been left out due to some issue with noise or stability. But still, no ground on the sheath of a heating coil that can act as an inductor. For use on sensitive components? It doesn't say much for the fine art of Chingineering. Since it appeared to function just fine all afternoon I just soldered a wire in where the resistor would have gone and connected it to the ground lug for the hot air gun. Thanks be to Weller, eh. A quick check showed continuity from cord to iron and when I plugged it in and turned it on the only smoke was from the iron where I had left it laying on the table. Oh well, all is good. It works and now I can finish some projects without all that cursing, maybe.
 Now don't get me wrong, I really like this 2in1 Soldering Iron Rework Station. And I certainly don't blame the importer for this little snafu. After all they didn't make it they just got it to me. Except the first one, who should take a.... I am glad actually that I now know how well this thing is built. It should easily last the rest of my life. Unless the zombie apocalypse happens because I will be too busy making brain pokers and zip guns to work on very much chintronics. If I need more flashlights or garden lights or even toilet paper I can always raid the stores that were staffed by zombie food.
If you think this little diatribe is too long then how come you're still reading it? But seriously, since ebay is bugging me to write a review of this device I figured it should be a doozy and serve multiple purposes. And besides Clive has made me smile more than once. So fair is fair.
Mike (o\!/o)

[PuchMaxi]

Good fix Clive! Sometimes you see the same problem on laptop power jacks (soldered directly on the motherboard).

[dashrendar]

Good to see that these units aren't completely junk. Straightfoward fix - thanks Clive.

[rud]

Clive, i purchased three off of a skytronic 703.123 base station 5 years ago these are used every day and have had no problems ever.... at the same time i bought 5 spare irons at £3.50 each i have used 2 spare irons at this point and would certainly recommend these to any serious electrical/ electronics practitioner . you have a great channel by the way!

[stevesm]

Always have a spare soldering iron.... Great vid Clive!

[MyBigThing]

WOW, THANK YOU FOR making this video. I was literally days away from saying "screw it" n ordering one of these cuz I'm sick of the $3 mains knew that takes forever to heat and the usb one doesn't get hot enough for certain stuff. you just saved me from wasting money on gear I don't want problems with once I pay good money for it! thanks again Clive!

[peterarnt]

Viewing this in 2020. Interesting fix. There are Amateur Radio manufacturers that use very similar connectors for their microphone jacks. Same issue with mechanical stress causing cracked solder connections on the front panel pcb. Great video...Well done, Clive.

[SamDeeksRelovedGuitars]

Excellent - thank you. That's what I'll be doing today - pulling this base unit out of my rubbish bin and taking it apart to make some fun new solder tracks. On my guitar set up / upgrade videos I regularly talk about how movement is the enemy of circuits in guitars and its true of all appliances.

[Thermalions]

21.7 C - Having a heat wave there Clive? Quite a bit above your preferred low teens isn't it.

[nealwright]

7 years later... I just fixed my trusty Katsu-chicken soldering iron using this method. Thanks!

[Inertia]

I recently got a second soldering station from China. From what I have gathered in personal experience and online research, these inexpensive Chinese products come with the basic skeleton and the concept is usually decent but will not hurt at all to at least go through and tighten up any loose strings and if you're feeling ambitious, a complete rebuild.

[FarWesternGarrison]

hi Clive, I very much enjoyed this vidjayo.
mostly because of your ramblings, but especially when you gave a small explanation of how op-amps work.
thanks for reading my comment