Aoyue Int 906C mini teardown, mod/repair and calibration (picture heavy)

[frozenfrogz]

Dear forum,

since I did not find lots of info on the Int 906C I thought it might be worth sharing with you.
I picked this dual soldering station with hot air and conventional soldering iron up some time ago for a decent price. Overall performance for my taste is OK, though the provided tip on the iron is not my favorite. The shape is good (small chisel type), but compared to the Ersadur tip on my trusty old Ersa MS250 the wetting is really shitty. It seems to be compatible with Hakko tips, so I will definitely try that out in the future.

Please excuse the picture quality, I was doing this at night and did not plan for really documenting the process and jumped into taking pictures half way through.

The problem

When soldering, the iron always feels a little cold compared to what I am used to. To double check, I hooked up the tip to a K-type thermo couple with a little help of solder for better heat transfer and – surprise – it read about 30°C low (320°C instead of 350°C). The station has got a calibration pot exposed through a small hole in the front. However, the pot was already maxed out. I got the iron to reach 325°C with what little reserve there was, but no more.
It was the same with all settings. I could hardly reach 400°C when set to 480°C, 200°C set gave me around 180°C.



Take it apart

One of the most usable tools when fixing, or modding stuff is a small wedge cut from a PTFE (Teflon®) rod I had stashed in my workshop from some experiment on isolators for my Ultimaker. This is an Ekonol filled PTFE, hence the brownish color. However, if you plan on making your own »warranty wedge«, any PTFE will do.



Just slide the wedge under the sticker and you will be able to keep your warranty Preheating the sticker a little with some hot air, might also help. However, the sticker on this soldering station was easy to peal back without preheating.


This is after surgery, seal intact, no warranty void.
Just like you would want in a perfect heist. In and out without a visual trace.


Here is what the inside looks like. Two cheap-arse PCBs, a small transformer, some wire and a vibrational pump.

The good, the bad and the ugly

The first thing I noticed when looking inside, was the awkward job at fitting the tubing on the pump. In parts the tubing is to short, or routed badly. This leads to kinks / sharp angles restricting airflow.




So much for quality control. But what do you expect from things that are built down to a budget?

The first thing I fixed was rerouting the tubing. I had to cut a piece from the inlet tube to have something to make up for the short connector.



Now that’s looking more like it



This is the PCB for the hot air part of the station. I just took pictures for reference – no modifications done.




Back of the iron temperature control board. Someone did a quality soldering job here!



Front of the iron temperature control board. Because of engineering level 1000, the board is held in place by the potentiometer screw nut (and the LED is used for indexing). There are two trim pots, labeled W2 and W4. W2 is accessible through the front. W4 is for coarse trimming.

Another design issue I ran into was, that the PCB was a pain to remove from the front plate. Although it is only fixed with a single screw nut, the wiring on the terminal for the soldering iron is so short, that the PCB needs to be wiggled and wiggled to get it far enough back to free the pot shaft from the front plate.
After setting W2 to the middle position, I had to really fiddle with W4. It was a pain to adjust, because it is really coarse. Measure temp, readjust, let it settle, measure, readjust, let it settle,... but eventually I was getting close to what could be called good on 250°C, 350°C and 450°C.

Edit: I forgot to mention, that my first modification to the station was putting some wraps of aluminum foil around the ceramic heater cartridge of the soldering iron. The tip had quite some airgap to the heater and warm up times, as well as thermal recovery were not very mentionable. Tightening the fit did improve things significantly.
As a short résumé I would conclude: The Int906C does a decent job in a tinker lab / maker space. The hot air part is quite powerful and the soldering iron is very ergonomic. However, you get what you pay for and should be prepared to patch it up before putting it to good use. If you were to need a soldering station for professional use, don’t bother with something like this and get some quality gear.

[bitseeker]

Thanks for the teardown and mod diary. The quality is pretty much as expected. Nice fixups.

[Avacee]

Edit: I forgot to mention, that my first modification to the station was putting some wraps of aluminum foil around the ceramic heater cartridge of the soldering iron. The tip had quite some airgap to the heater and warm up times, as well as thermal recovery were not very mentionable. Tightening the fit did improve things significantly.

Thanks for the tip tip and the trimmer info. I have a new Aoyue 937+ and its about to be sent back irrespective of whether I get a refund or not - It's a paperweight that just hits 240C when set to 480C and takes time to recover  from tinning the tip - proved utterly incapable at soldering two 14AWG wires together.

[frozenfrogz]

I forgot to mention that this sells for 89€ at my local electronics store. Overall I would say there is a lot of value for the money, given you are willing to DIY on what was missed by whoever slapped it together.

The metal case is very sturdy, provides a lot of space to stack stuff on top and I like the iron and spool holder that comes with it.
I figured, Hakko 900m and T18 tips should fit the iron. Oh and it is advertised as being ESD safe – the soldering tip is tied to ground, I measured about 1 ohm between the inlet connector ground pin and the tip of the iron.

[bitseeker]

Oh and it is advertised as being ESD safe – the soldering tip is tied to ground, I measured about 1 ohm between the inlet connector ground pin and the tip of the iron.

Good to know, especially when you don't want to short something to ground (e.g., changing a calibration memory backup battery).