Hakko FX-888 - Hum Noise normal?

hi there,
recently got my new hakko FX-888. As soon in turn it on, i get this nasty 50 hZ hum noise, while heating up which actually changes the hum noise in rhythm when the LED is flashes. Nice for sampling and making music, but a bit annoying when soldering. Worked for a couple of days with the same station of a friend of mine and it was dead silent. Or at least i haven´t noticed it. I did some research and found out, that some strong magnets can cause this hum, which here is not the case. No Magnets around. Some more facts:

  • the hum doesnt´t depend on the temperatur.
  • putting the palm of my hand on the left side of the case, the hum is getting way much quieter. near silent.
  • i opened it, removed the case and without case the station is dead silent.
  • tried to loosen and tighten up again all screws, but no difference.
  • tried to detached the transformer from the bottom by loosing the screws which connects the transformer and the bottom and putting some foam in between in order to absorb the vibration which obviously is produced my the transformer. just slightly quieter.
  • i thought it might by the table as a resonance body. therefore i put the station on a thick foam, but not difference. seems like the case is the resonance body.
  • holding the station in my hand, i can feel a slightly vibration at the bottom of the station.

Are there any hakko fx888 users out there having the same experience?
Any suggestion to get rid of this nasty hum noise?

Any comments and thoughts highly appreciated!

First, the LED flashes and the power is intermittent because of the thermostat: the iron heats up to reach the target temperature, then stop heating, then heats again when the temperature has dropped too much from the target.

The part that is humming is the transformer, and the hum is probably due to a mismatch in mains frequency. Is that a 50 Hz Hakko you have or a 60 Hz Hakko? What’s the mains current frequency in the country you live in?

My FX-888 makes a very quiet hum when the LED is on, IMHO nothing to worry about. Sounds just like yours. That’s the joy of transformers :slight_smile:

Interesting to know! I run my FX-888 through a 110V-220V converter because I mistakenly bought the US version, and thought the hum I got was from the 50Hz <-> 60Hz mismatch.

Now we need an objective way of measuring the hum.

My Zhongdi ZD-981 also hums when heating - i tend to think of it like a soldering station ancient work song - just like the slaves on the cotton fields used to sing.

its a 50hZ 230V Version bought in Italy. I´m loacted in Germany, but this souldn´t matter at all, right? I´m not sure, which frequency we have here in germany. another thing, as a newby, this could be a very dumb, but in a video tutorial for the hakko fx888 i heard, a guy took it apart and explained, that you actually can resolder the joints and therefore use it as a 110V AND a 230V Version.
edit: found this link. so obviously germany uses same voltage and frequency like italy 230V, 50hZ

Then I guess the hum you get is normal, is the one I get is not due to the 50Hz - 60Hz mismatch.