Weller WHS-M Teardown and discussion

[Benedict]

Hello everyone

My name is Benedict, Ben for short. I'm a medical student (5th of 6 years here in Croatia).
Just a bit about me, as this is my first post.
As i said, I do study medicine, and hope I'll become a neurosurgeon one day. I have no interest in hearding money and buying expensive cars and yahts like some surgeons out there do, i just like the brain, the great pcb of humans.
And.. built a 1000 000 volts tesla coil when i was 14, or so.. I like flashy stuff
I absolutely love physics and electronics, and do not approach it as a hobbyist, I'm quite serious about it, to the point that i tried to study it in parallel with medicine. That... didn't end up quite well.
but I'll try to get at least some degree in it as well, because i REALLY LOVE IT
My next project is a CNC machine, and I heartly recommend everyone to get/make one, for it's many many advantages.

So. The weller. Got in a nice box. Lots of colours. Nice.







Here you can see how they aim for that mobility aspect





Let's see what's in the box





Couple of manuals (safety information and usage), chinese made switching power supply 12 V @ 5A, sodering iron holder with sponge, 1 RT tip (there's 2 here, i ordered one extra)

 This is how the station looks like assembled. It's truly beautiful






The back panel is interesting, there is a DC 12 volt in, and soldering iron out, but notice 3 other holes. I think I'll mod the thing later, perhaps try to add tweezers. That'd be nice.





Made in Germany






The iron itself. It's kind of a 3.5 mm jack, in which 3.5 mm RT tips plug in, it's hot swappable






The ridiculously flexible cable, never seen anything like it








The iron looks like a pencil. This is the main reason i bought that station. It was quite expensive, 170 euros without tax, but it's the cheapest one out there you can get (some really expensive ones have them too) that has such micro RT tips and pencil like iron
For the money you can get same quality 2-3 stations and then some things, but i regret nothing, this iron is and feels fantastic. It has a movement sensor so when it's not used 5 mins it will cool down, and in 10 mins shut down. Tips have heating element in them, and are really well made. The smallest one is a 0.2 mm needle like tip. I know it's not as good as a chisel, but i like that kind of precision. Have to test it to see how it behaves yet, but those small and precise chisels should be perfect.






The thing IS a pencil


So yeah... i took Dave's advice and didn't turn it on, I opened it





Make your own judgement, but to me it looks .. empty. O.o
170 euros.. for... a practically empty pcb board? And one LCD display?
Also the board is held in place only by those 4 red plastic pins, not stable at all! And it's supposed to be mobile O.o
When you close it, when it's assembled it seems kind of stable though. But you can make a rattling noise if you shake it too strong, though i can't see why someone would do that.. still..








The soldering is perfect, but the board really seems empty to me.

ALSO. WHAT





LOOK AT THAT!

I can't believe it! A perfect board, and then that cap! Just bent down like that, and across the pcb edge?!! It's probably not a big deal at all but it hurts my eyes O.o
They really could have made that cap it a bit more sturdy, and have the board fixed with some screwes at least.. this way the only thing holding it in place is the pressure from the cover. And it's crap like that




Stress reliefs for that insanely flexible cable. Nice. It's double sided



A closeup on the holder and tips.
Tips are really nice, but unfortunatelly quite expensive so.. Better take care of those things.





Another nice thing is that  it takes next to no space.

The iron heats up in a mere 3 seconds from 0 to 400 degrees celsius. Amazing. Digital control works flawlessly, and the in built temperature probe is awesome and precise.

There is another version of this (a lot more expensive - i bet you can mod this thing into it without much effort) which has a BATTERY.

So you can, as advertised, when all normal people go to beach to enjoy the sun, sea, half naked girls .. or out there somewhere.. to breathe the fresh air..
NOPE SOLDER FUMES

yeah, you can solder on a robot pcb on a beach for example.



I guess this mobility has it's advantages but.. it's not at all sturdy, so I'd give it a second thought.

The iron itself and the station though, are perfect.

If you want i can film it. I was disappointed when I couldn't find any reviews on english on this thing, and only one video on wsm-1, a simmilar but not the same thing.

And I wanted to say, I've started watching all your vids from #1 to the end, currently on #68. Thanks for all, Dave

[nukie]

Thank you for the review!

12V is a good voltage to start with. I am guessing there are more chips under the LCD. Three LiPo in serial should make it portable, I haven seen a butane iron with SMD tips.

[Benedict]

My pleasure

Yeah i figured there probably are more chips under the display as if there aren't it simply can't work. It's controlled with a micro processor which can't be seen here so..
However look at the sheer amout of empty smd soldering places. It's amazing. It's as if the board was designed for many more products and they deliberately cut some conrers to make the price range. Which means if we get to see some other ones it could be modded into something else, maybe. I really don't know. Adding other irons should be a piece of cake though.

I think there is quite enough space for batteries inside, you'd only need to make a little switch for 12V in / battery, and figure out recharging, so it might be better to just make your own 12 volt battery as an external unit.

Also, I have no real knoweledge about them, but isn't the Li-ion a much better choice, in every asbect but price?

[saturation]

Thanks for the tear down, its a useful repair iron; as I was checking  prices in the EU these Weller's are fairly costly compared to more powerful but bulky units from competitors.

[M. András]

isnt this series have  a portable version with integrated lithium cells? i think that is blue colored

[madworm]

That looks amazingly like the WSM-1.

Have a look at that jumper... I wonder if that is used to tell the firmware what device it is ;-)

[saturation]

Yes, the PCB are identical pretty pricey too in the USA, near $400 

[Benedict]

Wow. That actually looks exactly the same, i see only one difference (+the jumper), the 6 pin chip in the right lower corner of the display (edit, on the left as well). Of course there could be more diferences under the display itself... it could be the same chip in different package however. Also there is another wire in wsm-1 leading into something. is that a switch?

I haven't really seen any substantial difference between this and wsm-1 in terms of.. anything (in specs) but i haven't looked hard enough i guess.. will go check it out

wsm-1 is a LOT more expensive

if that jumper is the only thing differentiating these things, that could be interesting

Thanks for the tear down, its a useful repair iron; as I was checking  prices in the EU these Weller's are fairly costly compared to more powerful but bulky units from competitors.

My pleasure. WSM-1 is even more expensive

EDIT

http://www.farnell.com/datasheets/409645.pdf WSM-1

http://www.farnell.com/datasheets/409647.pdf WHS-M

there are some useless things, like how wsm 1 comes with a metal wool instead of a sponge, and some temperature presets, locking, nothing so useful

there are three interesting things though, ESD safe, special functions for individual settings, and equipotential bonding socket that are present in wsm-1.

I have no idea what that is supposed to be 

equipotential? i know what that is, but what's the context? what bonding socket..
ESD? is that some industrial standard?
what special functions 

also the price difference is about 50 Pounds. A LOT.

[madworm]

The white wire goes to the grounding-socket. Not sure if that alone is worth the extra $. I guess the difference is all in the firmware.

What bugs me quite a lot is that they didn't find it necessary to use a socket for the solder-pencil at the back of the unit. I really don't like having a fixed wire going in/out of it. For that kind of money I paid for it 3 years ago, they could've spent the extra 10$ (parts + work) to add a DIN socket.

[saturation]

As its made in Germany, I can expect Weller to live up to everything its written in its spec sheet/instruction manual, including safety.  The manual says is reads actual temperature and if it heats up to 400^oC in 3 seconds, its as good as top commercial stations.  If this is so, the last item of concern are the durability, cost and availability of tips.  As for not having a socket, yes, its really built spartan to a price point but it can be forgiven if the specs are truly what the manual says it is. 

It would be good to confirm the heating speed and accuracy with a thermometer or thermocouple.

Touch the tip to a thermometer and ramp up set-points from 100-400^oC and confirm the temp readings match.  Then do the reverse, drop the set points from hot to cold and confirm both tip reading and thermocouple, allowing the tip to cool.  The station and thermometer readouts should be ~ same and match themselves as the tip heats and cools and then holds at the set-point. 

There will be some deviation between reading a thermocouple against the tip temp due to technique and the accuracy of the thermocouple.  But if the procedure is consistent, the reading will be precise but not entirely accurate, but that will be good enough. 

[madworm]

Well I haven't actually measured heat-up speed of the tip, but I can confirm this:

After you turn it on, the time it takes you to physically move the iron to where you need it, is enough for it to heat up to whatever temperature you set. At least for the WSM-1 it is quasi-instant. Heating up from stand-by temperature is even quicker ;-)

Heater-life is at least as long as tip-life. Differentiating between the two doesn't make much sense, as they're - unfortunately - inseparably joined. I had to replace the cartridge (36€-ish) that came with it after about 3 years of moderate use. The tip was badly eroded and thermal contact was miserable (had to crank it up to 400°C to get by). A new tip works just fine at 270°C. As I don't use the lead-free stuff, I suspect using the metal shavings as tip-cleaner may have worn the plating down.

Having to throw the heater away with the tip is quite wasteful, but I guess that is the price for having the heater / temp-sensor right inside the tip.

[Benedict]

ESD is electrostatic discharge then
special functions are probably nothing great, still unsure about that equipotential .. bonding socket, whatever they mean by it
I don't have a thermometer unfortunately, plan on buying a fluke 87 or so, so it'll have to wait. But it really is in mere seconds, it definatelly can melt solder in 3 seconds, that I guarantee.
So basically there are no significant differences to wlc-1. It's always possible to make a mod connection to ground then, and yes I agree dangling wire from the case itself sucks :/

Tips are retardadly expensive but you can get them online without a problem. If they last for 3 years, i think you get a lifetime supply of them for the price of some top of the line high end stations :/

[saturation]

Sorry to hear, but melt solder just means anything above the melting point of typical solder; 183^oC  at the joint which is the melting point of Sn63Pb37 eutectic lead solder or 227^oC for Sn99.3Cu0.7.  You can melt solder with a nail heated on a candle, what justifies a costly station are all needed electronics to regulate precise heat.

If the scale blanks out or won't read intermediate temps until a setpoint is reached it won't be possible to test 'real time' tip temp readouts.  Otherwise consider:

A simpler but less precise test.  Since you describe it heats very quickly, you may not have time to read temperature by just letting it ramp up and read the temp on the station when melting occurs.

Get the above 2 or just one eutectic solder to sample the Weller's scale.  Setpoint the Weller at exactly the melting point of each solder.  If it melts at that temp, the tip temp reading is correct, if not adjust it up or down 1C to the exact point, this is your correction factor.   You now have a ball of liquid solder at the tip.

Now, raise the temp to 400^oC to give you some time to observe the tip when solidus occurs.  Reduce the setpoint to 150^oC.  As the tip cools down from 400^oC the readout should show the tip temp in real time and will cool at a slower rate than when it heated up,  brush the liquid solder with a paper clip or such observing the station readout.  When the temp you see drops ~1^oC below the melting point you noted earlier, the solder should solidify. 

I don't have a thermometer unfortunately, plan on buying a fluke 87 or so, so it'll have to wait. But it really is in mere seconds, it definatelly can melt solder in 3 seconds, that I guarantee.

[Benedict]

A great idea

will test it and post results, thanx.

(next week though have a maxillofacial surgery exam on monday)

[Benedict]

Well got my multimeter with temperature (extech ex430) and I tried to measure the thing.

And yep the temperature does rise rapidly. However i don't really know why, the multimeter always shows at least 30 degrees C less then the station. And temp. rises more slowly on the multimeter. around 6-7 seconds or so.

eidt: my technique was wrong. the thing reads perfectly the same temperature and heats up instantly. can do a proof video if necesarry.

[M. András]

it have a different heat transfer, try to dip the probe into a solder blob on the iron you will see faster response not much faster but you will notice, and you can check if the station is low on temp or the meter reads low, set it to 180celsius and try a leaded or eutetic solder if it melts then the meter reads low

[Benedict]

Already did all of that, took me few minutes to see what I did wrong, never done it before.

Yep, in the solderblob it reads exactly the same temperature, with the delay of a part of second, maybe only 1 second max so yes it's working that fast indeed.

[saturation]

Great, I believe you;  you could still make a video to show how the eutectic solder melts at the exact temperature and youtube it.

Well got my multimeter with temperature (extech ex430) and I tried to measure the thing.

And yep the temperature does rise rapidly. However i don't really know why, the multimeter always shows at least 30 degrees C less then the station. And temp. rises more slowly on the multimeter. around 6-7 seconds or so.

eidt: my technique was wrong. the thing reads perfectly the same temperature and heats up instantly. can do a proof video if necesarry.

[Benedict]

Will try it, i don't have the proper setup to film anything :/
Will report back with video

[zagnut]

yes, yes, i know...my very fist post here and in an old dead thread...

anyways, i got the WSM-1C a couple of months ago and really enjoy it.  didn't really want or need the battery powered version but that's what came up NIB and cheap on EBAY.  $300 inc shipping is pretty good when you consider digikey wants $400 for the non batt version.  despite what i thought the battery power comes in really handy around the shop once in a while.

that long 1.2m cable coming out the back finally pissed me off enough to do something about it so i opened it up to shorten it and have a look around.  here's what i found:

removing the jumper (power removed of course) indeed changes the display to the WHS-M version without the two preset temps.   

all the empty pads you see in the standard version get populated for the battery handling.  the heater circuit also gets duplicated for some reason and my guess is that is the reason for the big diodes.  and if you thought that cap was a bodge then how about a big TO-220 regulator with heat sink hanging off the bottom edge of the board?

the battery is a 3S 18650 lithium-ion but with a nominal 9.9v and 1100mA capacity so i think that's what's called a LiFe battery?  no voltage boost anywhere to be found so apparently it doesn't need a well regulated power supply.  anyone that wants to do a battery mod to the standard model could just put a regular 3 cell Li-Ion inside and run a short lead with a barrel connector out one of the holes in the back of the case.  if 1,100mA is good for an hour then a 3,400mA pack would last all day.

under the display are just a few caps, resistors and a single 40 pin QFP,  obviously something designed to handle driving the LCD.

someone skimped on the loctite when they put my handle together,  the back part was easy to unscrew from the front...inside is a slim PCB with a bunch of small ICs and what looks to be the accelerometer.  pretty sure that some of the stuff is part of the temp sensing circuit.

and i don't understand the whole ESD setup.  from the handle to the plug on the side of the case is a separate conductor with nothing but a small choke near the plug.  inside the handle this ties in directly to the ground pin of the tip connector.....why the whole extra conductor?  couldn't they have just connected the plug directly to the ground inside the box?

so that's it, maybe i'll get some photos up later,

dave

[Henrik9979]

I modified mine to have 186500 batteries I salvaged from a laptop. Also I shorted the jumper so I would get the preset function.
When the voltage is too low the "bat" icon will start flashing and drop the temperature to 100c.

You can do it without the charge controller, I just did it for the sake of the batteries.