Youyue 858D+ some reverse engineering + custom firmware

[knotlogic]

On a slightly different note, I wonder if anyone has considered replacing the handpiece cable on their 858D.  The cable on mine was only about 30" long, making it impossible for me to swap hands or use a stand.  The PVC jacketing was stiff and always retained the kinks and folds from packaging despite my attempts to straighten it with a heat gun.  The part that unsettled me is that the conductors appear to be 24AWG, even the heater and ground conductors.  I don't know if the other clones are similar (short cable, small wire), but I wouldn't be surprised if it were yet another 'feature' of my particularly crappy clone. 

I've thought about it, but had no idea where to get a suitable multicore replacement.  I'll probably try replicating what you did at some point.  Thanks!

What did you think of the quality of the eBay silicone wire?  I'm looking at getting some, but my concern is finding a quality source that sells in small (eg by the foot/meter) quantities.

[DGM]

I'm kind of thinking twice about my choice of using a silicone jacket.  It's flexible and heat-resistant and all, but it has such a high coefficient of friction against everything.  It tends to drag other things off the bench.  It would probably be a lot easier to use/assemble if you used some braided wire loom instead, but you'd give up the heat resistance. 

The ebay silicone wire is like any wire on ebay.  You have to gamble.  You might get PVC insulated wire; you might get steel wire.  The last few times I've used this source, but nothing is sure to last forever:
https://www.ebay.com/itm/Flexible-Stranded-Silicone-Rubber-Cable-28-26-24-22-20-18-16-14-12-10-8AWG-BS1/263048836899?ssPageName=STRK%3AMEBIDX%3AIT&var=562051445968&_trksid=p2057872.m2749.l2649
The wire there seems to be okay.  As far as only ordering what you need, I've found that this stuff is great for making jumpers and test leads anyway, so the excess is always welcome as far as I'm concerned.

This was the tubing:
https://www.ebay.com/itm/2M-Clear-Translucent-Food-Grade-Silicone-Tubing-Milk-Hose-Pipe-6x8mm-Q7M4/122613669781?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
But there's also this stuff I was thinking about:
https://www.ebay.com/itm/ALL-SIZES-1-FT-100-FT-Black-Expandable-Wire-Cable-Sleeving-Braided-Tubing-LOT/222303786890?hash=item33c256978a:m:m15OUGA3MPjLlj3OHeEVxkQ:sc:USPSFirstClass!62272!US!-1

[DGM]

I'm sure there's some information about fuse settings somewhere in the past 600+ posts in this thread.  I'm only going to do so much to play encyclopedia here.
Off the top of my head, I remember this post:
https://www.eevblog.com/forum/reviews/youyue-858d-some-reverse-engineering-custom-firmware/msg1320798/?topicseen#msg1320798

[knotlogic]

I'm kind of thinking twice about my choice of using a silicone jacket.  It's flexible and heat-resistant and all, but it has such a high coefficient of friction against everything.  It tends to drag other things off the bench.  It would probably be a lot easier to use/assemble if you used some braided wire loom instead, but you'd give up the heat resistance. 

Guess it's a trade off?  I have a Metcal, and I think the lead on the handpiece is silicone.  It is rather grippy, but not so much that it's awkward to use.

If you're considering braided sleeving, you could look at Techflex.  They have a lot of types, and I got some stuff that's very soft and supple. (Can't remember if it's monofilament or multifilament or something else.)  In contrast I picked up some other stuff from a audio parts seller, and it was very stiff.

This is the eBay store I got my Techflex from (no relation ):

http://stores.ebay.com/FURRYLETTERS?_rdc=1

[bitwelder]

All in all, why there are so many h/w variations of this desoldering tool?
I tried to follow the design of the various versions, but I did not notice a clear 'evolution' path, neither in features nor in BOM count reduction.
If there is no advantage why not just copy the project as-is?

[DGM]

Guess it's a trade off?  I have a Metcal, and I think the lead on the handpiece is silicone.  It is rather grippy, but not so much that it's awkward to use.

I think you're right in that regard; a lot of the other silicone jacketed tool leads I've used aren't this bad.  Some are even quite slippery.  The tubing I got (and really all the silicone tubing I've ever used) is a lot grippier, especially against itself and even the other silicone leads which aren't as grippy themselves.  I don't know if there are special formulation or finishing differences between the materials, but I haven't had high expectations of being able to find another tubing product that had significantly different surface characteristics.  It's not exactly a figure of merit for the application as a tubing.  Of course, I didn't consider buying anything that was significantly more expensive, so I maybe I'm just missing something.  I suppose one could just order some shorter bits of different tubing as samples.

I suppose an intermediate solution would be to use the silicone jacket for flexibility and density, and just put some sleeving over it in the area where it tends to rub on the other things.

EDIT: dammit.  I looked at that the sheen of that techflex, and I just realized that I actually have almost 500' of hollow-braided nylon support strand.  That's not exactly intended as sleeving, but it's just the right size and I bet it would've worked just fine. 

[DGM]

All in all, why there are so many h/w variations of this desoldering tool?
I tried to follow the design of the various versions, but I did not notice a clear 'evolution' path, neither in features nor in BOM count reduction.
If there is no advantage why not just copy the project as-is?

Idk really.  I  can see there are similarities within a given manufacturer's designs (like the Yihua/WEP boards), and it seems some of the other boards are also manufacturer/brand specific (the Hyiko), but I don't know the driving motive to redesign.  I kind of figure everyone would just copy what's existing, and you'd see varied evolution from one source with variation dependent on available parts, cost, etc.  Maybe certain outfits do take some interest in at least trying to do their own design work.  Still, a progression of copy/paste designs may well have been able to yield something better by now.

I can see why the YH858DVx  and the YOUDE boards use odd button sensing; for some reason they decided to use SDA/SCK lines as single-duty and ran out of I/O pins.  The Yihua is based on early 20-pin clone designs, so maybe nobody else had done it differently at the time.  I could see why someone might redesign the TC amp to something based on the LM358 instead of the original part, but then I can't see why someone would just randomly adjust the resistor values in the fan driver circuit.  I could see why someone would do a board redesign to make use of cheap smt chip parts, and I could see why they might omit the recurring cost of isolation routing, but why not spend an extra ten minutes to clean up the spacing in the layout itself?   I can even see why they used the handpiece connector that they did.  Those radio connectors are ubiquitous and absurdly cheap.  I don't consider the connector to be anything other than a means to conveniently replace the handpiece.  Consulting common sense over standards, it seems no more a hazard than a lamp socket.  They'll roll with that.

That said, I imagine there are a lot of the unfortunately typical conflicts of interest at play in the timeline of a given design that might drive apparently bad design choices just as much as mere inexperience or oversight.

[bitseeker]

All in all, why there are so many h/w variations of this desoldering tool?
I tried to follow the design of the various versions, but I did not notice a clear 'evolution' path, neither in features nor in BOM count reduction.
If there is no advantage why not just copy the project as-is?

Perhaps it's not so much an actual advantage than a perceived advantage (or differentiation). "No, this is not a copy. It's our own design and 'better.' So, you should buy ours instead of that copycat version."

[DGM]

Perhaps it's not so much an actual advantage than a perceived advantage (or differentiation). "No, this is not a copy. It's our own design and 'better.' So, you should buy ours instead of that copycat version."

I understand the pestilence of marketing and the importance of appearance over substance, but I still don't see that it explains the internals.  Sure, everyone has their own little badges on the outside, but considering the clones are pretty much identical externally, it seems a bit weak in terms of effort to differentiate appearances.  Nobody markets their particular clone based on differentiation of its internals, and yet there's more differences inside than outside.  It seems to me that everyone wants their product to look like some archetypal 858D.  In that sense, I'd say the internals differ since there's no need to make them maintain a common appearance if nobody sees them.

Then again, it's kind of curious that some do specify the microcontroller branding.  Still, that much might not even be an actual feature claim, but an attempt to avoid complaints from people that bought it expecting an AVR.  Who knows.

[DGM]

Over the development of these mods, there have been a handful of approaches to measuring the fan speed.  Though I don't know what the original Youyue firmware did with it, most of these seem aimed toward using the fan speed only as a safety interlock, but I'm pretty sure I recall at least a mention of actively adjusting PID parameters or otherwise adapting the control to the variable physical system (e.g. nozzle changes).  I'd like to know if there really is much desire to use the fan speed information in this way, or whether the standing assumption is that fan rpm is sufficient toward such a goal.

I ask because I'm fairly certain that the trivially measurable quantities (voltage, current, power, speed) aren't really appropriate as a proxy for mass flow information.  I'm also curious to know if nozzle changes and blocked inlet/outlet conditions are unambiguously detectable without more involved modification.

I suppose measuring anything more would require electrical access to the handpiece, but I've demonstrated that cable replacement isn't prohibitively difficult and may have practical benefits of its own.  I've been playing with the idea of a MAF sensor of sorts to directly detect the flow.  I would figure that flow data would better fill the role, whether for the purpose of a safety interlock or some part of heater control.  It all depends whether anyone would consider going to such lengths. I suppose it also depends whether my half-baked idea has any better practical accuracy than inferring mass flow from fan speed, but I shouldn't get ahead of myself.

So any thoughts?  Interlock only or active control adjustment?  Too much work for what it's worth?

[floobydust]

Fan speed is not monitored on the station.

For more precise temperature control it is of limited use, as your nozzle size and proximity to the PCB affect flow rate and these are unknowns to the firmware.
People wanting sub-degree accuracy I think it's unnecessary IMHO because the wand position is all over the place.

You could model the fan curve, looking at its datasheet and knowing RPM, to model mass flow but the nozzle size would be tough to infer. You could do a self-learn, and compare fan voltage and resulting RPM to estimate torque.

I reliably sensed fan speed via commutation-current (no need to access wand) in this post: https://www.eevblog.com/forum/reviews/youyue-858d-some-reverse-engineering-custom-firmware/msg1204635/#msg1204635
But I found you need another MCU timer channel to get RPM, so I abandonded it as the AVR Mega328 would have to change to the newer '328PB which has more timers.

Fan speed for safety, the original firmware does look at rate of temperature rise (slope), to infer if the fan is not working. If temp climbs too fast, you know the fan is pooched or blocked. This seems to work well enough.

[DGM]

Well, as far as accuracy goes, so long as there's an I term in the control, flow information shouldn't have any impact on steady state accuracy.  If you meant that the board temp is immeasurable, yeah I wasn't trying to extrapolate surface temps based on flow or anything like that.   I was thinking mostly for adjusting dynamic response.   I'll accept that it's probably unnecessary, but that's kind of a theme here. 

I didn't notice that bit about temp slope sensing.  That would detect blocked inlet/outlet conditions, which is something that voltage/current/speed methods can't sense.  That actually seems entirely sufficient.  If the firmware can already safety-check using temp slope, and nobody is using the fan speed for dynamics, what's the point of sensing it at all?  Is this redundancy or just an artifact of prior methods that were abandoned?

I still hold that direct flow sensing could be done for the purpose of the aforementioned control parameter adjustment -- for whatever marginal benefit that might be.  I was kind of under the impression that tan speed was actually being used for something.

[stj]

maybe an external "calibration" sensor would be good,
you point the wand at it after changing nozzles or fan speed and the software uses it to create an offset for the original internal sensor???

[DGM]

I hadn't really thought of that approach.  It seems simple to implement, but it'd require explicit interaction to recal after speed/nozzle changes though.  I don't see an easy in-process method to extrapolate temperature beyond the nozzle.  Some hot air stations allow the thermocouple to be repositioned to minimize offset.  I've had the heater apart, but I don't think anyone here would be too willing to modify the heater to get an adjustable probe.

Myself, I'm not terribly interested in anything beyond the nozzle.  It's an arbitrary thermal system.  What matters are the temperature of immeasurable components that will heat at different rates.  I expect the station to just be a consistent and stable heat source; managing heat external to the tool is a matter of user experience and judgement -- or better equipment when required. 

I was thinking of using a compensated thermal anemometer as a mass flow sensor in the handpiece.  I was after optimizing control dynamics, but I don't know if mass flow information would be of any use in projecting temperature.  I don't really think so. 

[mjguisado]

Hi all, maybe the best approach is to have an external thermocouple measuring the temperature in the area that is being heated. This would provided to the PID algorithm the required feedback. And maybe it's could be directly connected to the input where the current thermocouple is connected in the different boards.

[stj]

the *real* answer is to move the thermocouple into the nozzle, but i cant see any easy way to mechanically do that!

[DGM]

Hi all, maybe the best approach is to have an external thermocouple measuring the temperature in the area that is being heated. This would provided to the PID algorithm the required feedback. And maybe it's could be directly connected to the input where the current thermocouple is connected in the different boards.

While using a secondary temp input to allow some sort of component/region temperature limiting might be nice, it might not be worth the setup unless you're doing something like a single large component. 
One thing for sure, you wouldn't want to replace the original TC input with a board mounted TC. If you did that, the thing would burn the heater out the moment you moved it away from the board.  I suppose maybe you could switch to an external TC if you had everything in a fixture or something, but you'd have to be mindful to not let it lose feedback.

As far as adjusting the TC position further into the nozzle, It might be possible if you were to machine a clamp bushing to hold a sleeved TC into the end of the heater shell.  Of course, you'd have to probably grind out the cement that holds the original TC into the heater support. Seems like a lot of work for a minor gain.  Using a sleeved thermocouple means you'll probably have slower response time too.  I know I said mass flow probably wouldn't be very good for projecting temperature estimates beyond the position of the stock TC, but it'd probably require less work to attempt ... at least less of the kind of work most people are going to be reluctant to try.

[LeonR]

This topic is quite big and I still couldn't figure one thing out: Does the "maker" (or labeller) of those 858 stations make any difference quality-wise? I'm looking for a hot air station with basic features but I'd love to have it in a good working condition outta the box without messing with it (be it inverted cables, no grounding, inadequate internal wiring, etc). From the myriad of options, does any of them stand above?

[bitseeker]

Generally speaking, it's hard to say because they tend to change over time. Perhaps someone who had bought one recently and had a good experience can post which one they got and from which vendor. That'd at least increase your odds of getting the same outcome.

[DGM]

This topic is quite big and I still couldn't figure one thing out: Does the "maker" (or labeller) of those 858 stations make any difference quality-wise? I'm looking for a hot air station with basic features but I'd love to have it in a good working condition outta the box without messing with it (be it inverted cables, no grounding, inadequate internal wiring, etc). From the myriad of options, does any of them stand above?

I don't know about one that stands above, but I can think of one that stands below...

As far as I recall, the chassis wiring flaws are basically universal among brands; expect to at least safety check anything you buy if you're the critical type.  As far as firmware and quality of the PCB assembly, any model based on the 858D06 board (e.g. newer YOUYUE 858D+, UVISTAR 858D) are probably among the better & more common sorts.  I still stand by my declaration that the Zeny branded units are essentially defective.  I don't know how much variation there really is in handpiece assembly quality.  I'm willing to bet those are basically all the same. 

bitseeker is pretty much right.  All this information comes with no assurances that the manufacturers won't change something.  For my own research, I didn't consider branding to be really meaningful.  Ultimately it's the internals that are the deciding factor.  It's the relationship between observable attributes and useful attributes that is impermanent, so be careful. 

As far as trying to navigate this giant mess of a thread, the spreadsheet in this post has an index of all the posts used as examples of each board type.  This way, you can find photos of internals of all the different kinds and make your own choice.   The index is as comprehensive as I could manage, and includes all board photos I could find on the web.  Some of the references do mention where they bought their unit, so that might help too.

[brainwash]

Just to be clear on newbies (myself being one), absolute temperature control means nothing. People with experience on one tool can easily do BGA or SDRAM without breaking a sweat. They are ALL a few degrees off, with overshoot, undershoot and other problems. But you can see all the professionals on YouTube doing an iPhone chip exchange/upgrade without any issues.
The key is practice and knowing your tool, while avoiding insurmountable challenges (for example a PS3 GPU).
Saying this as I've been able to work ok for a few years with an un-modded unit, recently got a slightly better one as a present. The learning curve is almost as day zero, regardless of feature.

My point is: practice from day 1, so you can be secure when you actually need to use it for something. +/- 15C will hardly make a difference compared to the way you handle your parts and wand.

[DGM]

Just to be clear on newbies (myself being one), absolute temperature control means nothing.
...
My point is: practice from day 1, so you can be secure when you actually need to use it for something. +/- 15C will hardly make a difference compared to the way you handle your parts and wand.

Yeah, pretty much.  Practice makes up for a lot.  Disassemble and reassemble an old motherboard a few times to get comfortable with it.  A few mm distance will change target temperature just as much as a minor calibration error would.  A few degrees offset or in overshoot isn't even really noticeable in most cases.  A few hundred degrees like my Zeny? That's something to avoid from the outset. 

[a.ekholm]

Hi! I'm interested in the Atten hot air station and stumbeld uppon this thread and tryed to get a Picture of this soldering station is worth the money or if there is better soldering station for the Money with working PID? If the atten or simular is the key, can someone Point to "the right one" in EU so i could buy the right stuff.. Thanks /Andreas

[DGM]

If you're asking about an Atten specifically, I'm going to assume you're doing so because you saw an old review of one.   As far as I recall, and someone can correct me if I'm wrong, the Atten units like you see reviewed on EEVBlog are not what you'll find currently.  Those units from 2010-2011 were based around an AVR microcontroller.  The last Attens I have record of internals are from 2016.  Those newer ones are based on the 858D04 board with a different microcontroller.  I don't know if they're still shipping with that board or whether they're shipping with the newer 858D06 board.  Then again, maybe these newer examples aren't legit Atten units.

If my assumptions are correct, a current Atten is likely going to be identical internally to the Youyue, Uvistar & others.  Among the 858D clones, it's probably going to be one of the better ones, but they all have the same problems you'll need to be aware of.  Refer to my comments a few posts back.  As far as picking "the right one", that's up to you.  I'm just commenting to make sure your expectations aren't being based entirely on old information. 

[DGM]

I went to try finding newer examples of Atten internals and I found something interesting.  There appears to be a new kid on the block -- at least new to me.  The most interesting part is that it's an AVR-based design and the firmware behavior appears similar to the older Atten units.  The board is entirely different than anything else in this thread.  Because the panel layout is different, it should be easy to identify, and there's less uncertainty of the board type within.  None of the other boards would even fit.




aliexpress turns up results for "mypovos 858d"

I had avoided looking for references on YT because it's basically impossible to do it effectively on a <1Mbit network connection.  It's incredibly slow to skim videos, and at 240p, you can't see board marks or anything relevant.  I may see if there are other bits to add to the index, but don't count on it.