Powering a Hakko FX-888 - Possibilities!

[xibalban]

Hi guys (and girls too  ),

After much research, I've decided to buy a Hakko FX-888 Analog Station as my first ever Soldering Station. I'm hoping to grab a good deal somewhere from Amazon or Ebay, etc. The equipment would be rated at 110V, 60 Hz and I won't be able to directly plug this into my household 220 V, 50 Hz supply. I looked around and using a 220/110 step-down transformer was the popular solution.
I, however, wish to do something different, and seek your assistance.

One of these days, I'll be building my variable power supply (yes, my first project  ). I wish to incorporate, among other output levels, a 26 V regulated DC output.
I was hoping that I could remove the transformer from the Hakko FX-888 and connect the station directly to this 26 V DC output from my power supply unit.
I'm sure someone has tried this already. Comments please!!

Cheers!!

[amyk]

The heater runs on 24VAC and I believe the controller uses a triac, so it won't work with DC.

[xibalban]

Well, 220 V versions are difficult to find and are very expensive. Also, the odds of the equipment being a clone is very high.

Coming back to the original problem, how about I feed the station with 24 V AC then? Or replace the transformer inside the unit with a 220/24 V version instead of using a 220/110 separate transformer?

[xibalban]

Well of course if you make a modification such that the rest of the unit is operating identically as it would if it was being powered by 120VAC then everything ought to work.  I have no idea if anything they do checks or works with the 60Hz or 50Hz based line frequency, so I suppose it is theoretically possible that timing and not just voltage could be affected.
Interestingly if you download the FX888D user manual (I assume the same generalities may be the case for the FX888) it shows a parts list diagram of the internal parts and it shose a part number for the 120VAC transformer and another part number for the 220-240VAC transformer.  On the next page it shows one part number for the 110-120VAC PWB, a different PN for 220V PWB, a different PN for 230V PWBm a different PN for 240V PWB. 
Who knows maybe you could even order the appropriate transformer and PWB as "spare/replacement" service parts if you wish.  Of course there are numerous different part numbers for different plug+power cord assemblies.  The heater is listed as just one PN, 26V, 65W, so that apparently does not change for the different variants.  I have no idea if the FX888 analog is the same, you should look if you wish to see the options.

If you can find anyone that has published the schematics of the 2xxV PWB and handle interconnect as well as the 120VAC one you would have a better idea what else you might have to change besides the transformer.
But if you have no idea what other changes to make on the PWB and you do not order a genuine 2xxV transformer + PWB it seems almost like you should just use a 3rd party handle controller PCB design so at least you know what the correct hook up is.

I guess if you could use a high quality 2xxV 50Hz to 120VAC 60Hz conversion power supply you could measure the various voltages going from the transformer to your PWB and find out what must be the alterations to suit changing the original transformer for some other one and still be compatible with the rest of the circuit.  Maybe it has several different low voltage windings, I don't know.

Phew . Now, that appears to be quite a challenging assignment for someone who doesn't even possess a soldering station to begin with . I ought to have studied the schematic of the equipment under question, instead of just assuming that like most electronic circuits - the input would be rectified to DC anyhow before feeding to the main circuit. It seems more reasonable to use a 220/110 V step-down transformer for the station, after all. Thanks for the eye-opener .

[xibalban]

You could probably feed it 24V AC, but that's what the transformer is for anyway...

That's been my very point from the onset. This guy seemed to have experimented and scribbled his success as well.

[xibalban]

I've recently discovered (read somewhere) that the mains transformer on Hakko soldering station comes with a tap for switching between 110V and 220V input voltages. If that's true, I've just lost a treasure trying to pay about $35 more for the 220V version that I bought.

Please say that it isn't true  !!

[Shock]

They aren't or at least weren't multi tap 240v transformers so no. The 110v Hakko FX888 was going for under $70 US at Frys at the beginning of the year.

[Richard Crowley]

If the device uses phase-angle switching for the SCR, even if you replace the transformer to provide the proper voltage, will the mains frequency be an issue here? Is the circuit sensitive to the AC frequency?

[loneoceans]

Hey everyone's thinking too much into this. The mod is easy and straightforward.

The easiest way to go about doing this is to either power the Hakko from a 240 to 120V step down transformer, or simply buy a separate 60 to 75VA transformer to replace the one inside. I'm very sure anything from 24, 25.2, 26, 28VAC will work just fine, and no need to worry about the frequency either. The feedback is from the temperature of the heating element and the triac controller will work just fine with 50 or 60Hz. The only thing you need to worry about is to make sure the transformer physically fits. Digikey and Mouser are your friends for this.

Example transformer: http://www.digikey.com/product-detail/en/TCT50-02E07K/237-1595-ND/3995763 (if it physically fits).

The reason why voltage / freq isn't a bit deal - many places even within the same country experience significant voltage fluctuations, ranging from say 210V to 250VAC. Even within Japan, their two main circuits are 100V 50Hz or 60Hz, and it's not going to affect the operation of your iron since the feedback takes care of all of this to make sure the iron tip is at the right temperature - the soldering iron is just a temperature regulated heater.

The only other part you might want to change is the fuse for half the value in the 120V one, including any protection things like MOVs on the input side if any (I don't seem to see any of them in teardowns).

Here's another example - https://www.eevblog.com/forum/reviews/hakko-fx-888-teardown-review/

No need to think too hard about this and it's a straightforward mod. If there are no transformer taps, just pop out the transformer and put a new one in.