Solving the issues present in the new FC660C



Despite being made in Japan, new black-on-black FC660C is a host to a wide variety of quality control issues not present on the earlier grey-on-black or white-on-white FC660C. The most notable issues are

  • Scratchiness in the keys - present in the old FC660C but at least an order of magnitude worse here

  • Clicky springs - whenever you type, you can hear the springs clicking against themselves - it’s very loud and you can feel it too (it feels disgusting and clearly broken)

I’m not the first one to report these issues. A few earlier posts note similar issues:

“I just got this thing today and it makes some serious noise. The spring ping (which is present on some keys on the older models) is significantly louder than it used to be (just as loud as the upstroke) and typing on the keyboard sounds absolutely awful… I’m thinking they might have changed the springs, unless they are just horrible misaligned […] I have never touched such a terrible sounding topre board in my life.” by /u/the_fascist

Anyone that has owned a first-gen FC660C knows that they are a dream to type on. They are great out-of-the-box, but they become legendary (become perfectly smooth, any remaining clicks become thocks, etc) once you do the following two mods:

  • Apply lube to the slider rails / where any pieces of plastic slide against one another
  • Apply silencing rings (KBDfans Silence-X)
  • Optionally, get Hasu’s controller to run QMK

Warning: It should be noted that lube can reduce the tactility of Topre domes due to the increased force required in pushing the domes up or down. Apply an extremely thin layer of light lube if this concerns you. If you’d like to increase tactility, get BKE domes. I am personally not a fan of these - lubed Topre boards feel more “refined” to me despite the slightly lower tactility.

Anyways, applying these mods on the new FC660C did nothing. The keyboard was so bad that the mods that had an incredible effect on the old one were completely overwhelmed by the issues with the springs. For me, this confirmed that the issues were, in fact, in the springs.

But rather than lube the springs, I realized that Topre boards are capacitive. You can just lube the board itself and you won’t prevent actuation because no two pieces of metal actually need to touch.

And so I lubed the PCB itself. A really dumb idea, but it did the trick. The new Topre feels and sounds like a dream to type on - even better than my Gen 1 board! This probably also implicitly lubes the springs themselves. Lube all the things.

Warning: Using petroleum-based lubes can and probably will disintegrate your domes over time. Try a silicon based lube. Also, IDK if lube is flammable or whatever. Hopefully no lube is in between any two points of electrical contact with a high enough voltage to ignite :slight_smile: if this worries you just be careful and make sure the lube stays in and around the white circles. I was out of warranty and out of time, so this was a last shot at trying to improve the board before I just gave up on it. I’m glad it worked.

TL;DR: Fix the new Topre boards by

  • Lubing the PCB itself
  • Lubing the slider rails
  • Applying the KBDFans silencing rings


Did you use a Dielectric grease on the Pcb, and how thick of an application of grease did you apply on the pcb to resolve the issue. I just order my FC660C from Korea, and if I too have this problem then I’d like to do it right.


I just used normal lube. A very very light application.


Really interesting. I was expecting a QC upgrade when they switched from China to Japan. Guess they screwed up some tolerancing in the process. Glad there’s a fix for it though.


Thanks for providing this, it was really informative. I’ve been having issues with my 55g domes where it sounds like it’s sticking to the PCB. I’m going to try to lube my RF PCB and see how that goes.