YOUYUE 858D+ hotair station — teardown

This device seems to be a clone of several other branded ones out there. The Atten / Aoyue 858 come to mind ;-) I bought it on ebay for 38€ delivered.



I think I’ve read some stories on the eevblog forum regarding bad mains wiring, so my first job will be to do a teardown and making sure that the safety-earth is wired correctly. See the images and my findings below.


At first glance, it looks pretty decent – considering the price! No loose wires or screws were encountered. The spade connectors used for the power input / safety-earth are self-locking. Nice. They’ve also added insulation sleeves. Nice.


Two of the mounting studs were cut off, so I wonder if the circuit board came from somewhere else.


There are plenty of HV isolation slots to be found. Nice.


Another indicator that the circuit board doesn’t quite match the front panel.


The circuit boards weren’t cleaned it seems. The opamp is an OP-70, used to handle the thermo-couple in the heater.


And now to the serious issues I’ve discovered so far:

Once the power switch is turned ON, one of the pins on the circular connector is potentially live! The CEE 7/7 mains connector is not necessarily used with a polarized outlet, so there is a 50/50 chance to have exposed mains voltage on the device. Not good. I’ve added a “! DANGER HV !” sticker right next to the connector. They should’ve used a different connector. Some of the other brands selling this device chose to have the wand permanently connected, avoiding the issue completely.


The inside of the wand looks acceptable, if it weren’t for the fact that some of those tiny wires carry 220V and about 3A (700W heater).


This my friends is a not-so-safe safety-earth wire. The connection is not something I’d bet my life on. I tried to solder the wire to the heater tube, which of course didn’t work. The tube doesn’t take the solder at all – and it gets too hot anyway, so it melts again, once the heater is turned on.


They should have used a spade connector for that wire!

In the end I had to redo this lousy way of hooking up a safety-earth wire. Not proud of it. I made sure there is some tension on the wire, so chances are higher the connection is not intermittent. But I guess I won’t be touching the metal parts while the thing is turned on (or hot). Maybe it is time for an insulation transformer. For some reason these things are prohibitively expensive for what they are: a box with a chunky transformer, some outlets and a resettable fuse.


Usability will be dealt with later. I have some victims to play with already.

All the images for your pleasure:

Here’s what Mr. EEVBLOG himself had to say about a very similar device some 2 years ago.

My next post will deal with using the device.

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12 Responses to YOUYUE 858D+ hotair station — teardown

  1. Jack says:

    Thanks for the review and teardown, also the Youtube video. Very informative!

  2. Andrej says:

    Great teardown. About the grounding connection in the wand, try to use a small screw that will holt the wire in place. The current solution seems very unreliable. :)

    • robert says:

      Yes, that grounding wire sucks. Unfortunately there is very little room in there. A screw + nut would probably not fit. Using a grinder to cut a tab into the metal and using a spade-connector might be feasible.

  3. Dirk says:

    Hi Robert,

    >I think I’ve read some stories on the eevblog forum regarding bad mains wiring, so my first job will be to do a teardown and making sure that the safety-earth is wired correctly.

    That was a wise idea (I unfortunately had overlooked…)

    After reading your blog i decided to order a YOUYUE 858D+ at amazon. Three days later it stands on my workbench ready for a first test. First all seems to be ok but when I put the wand back to its holder i got electric shock. A quick test with the multimeter shows that the housing was on 230V AC but this only if the statition was switched off (still plugged into the mains).

    Now I’m waiting for new one – hopefully without any defect.
    The first thing I will do if the replacement arrive is to follow your advice and check the mains wiring ;-)

    • robert says:

      Not good :-(

      If the case was live, the GFI should have triggered and turned everything off. Was the PE (yellow/green) wired correctly?

      Have you tested your GFI (see breaker-board) lately? These things should have a test-button and shut off when that is pressed.

      • Dirk says:

        >Was the PE (yellow/green) wired correctly?
        You made me curious – so I reopen the parcel (waiting to be shipped tomorrow) and took a look inside the case…

        At first glance the wiring seems to be correct. Then I measaured the connection between PE and the case – nothing! It seems that the painting of the case isolates the PE-Screw (at the bottom, near the transformer). But what I didn’t found at that quick investigation was the source of the current. Maybe reflux from the heating?! The strange thing was that the case was only hot if the switch was in OFF position…

        • robert says:

          Unfortunately that seems to be a typical issue with painted metal housings.

          Best to make sure that all metal parts show good continuity to PE (< 1 Ohm), especially the metal nozzle of the heater and the metal connector on the front panel. You may have to scrape away some of the black paint on the case and some of the white paint on the front panel.

  4. robert says:

    The front switch is just a single-pole switch! Depending on how you plug in the AC connector, it either switches L or N.

    I suspect that in your case it was switching the N and there was some leakage. With the PE not properly connected (due to paint), the voltage had nowhere to go and the case was live. With the device turned on, the leakage might have drained away to ground.

    It is possible to replace the power switch with a 2-pole one that fits the cutout in the front panel.

  5. Al says:

    Thanks for all your efforts…the info, vids & mods etc. I recently purchased the exact same model. I purchased this one as its easy plug in handle lead ( so no need to take apart unit to replace handle) (I dont mind the live pin :s as the handle lead is always plugged in & only needed to unplug if its handle replacement time) ( OK the male female plug in socket couldve been designed the other way around, that way it wouldve been insulated live pin)
    Anyways its a nice station :) but Im very concerned after reading on net about wiring. I noticed on the paper sticker label (label couldve been made better, the print, model, serial number etc is rubbing off) the label on the back of my unit states that theres meant to be a 5A fuse…but all I can see is a small empty hole, Ive seen on vids some 858D variants have a screw-in fuse located at that point. Is this correct? does YOUYUE 858D+ have fuse there ? or not? I cant take the unit or nozzle handle apart because theres tamperproof warranty stickers over the screws. So this means I cant check internal wiring of unit or handle :( I’ve found one 250V glass fuse in the part where AC lead goes this correct? Thanks for any further advice.

    • Al says:

      edit :) by socket shouldve been designed other way around (handle lead connector)
      Take a look at the Pro’sKit- SS-969 handle lead connection socket design ;)
      I took the plastic bit out from near the AC lead (where it states 250V fuse) I see the glass fuse is indeed 5A 250V so this must be the fuse :s I guess that hole near sticker is because this unit is some sort of generic design.

      BTW 7 segment blue LED mod would be kewl :)

  6. Marcelo says:

    hi there,
    can you please measure the display window?
    I would like to buy one and build a controller with a nokia 5110 lcd. Do you think its possible?


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