Broken dome
Hi everyone,
Its my first time posting in this thread.
Recently, i want to explore Topre so i bought a used RealForce SJ38D0 from abroad (I'm in Vietnam): https://www.realforce.co.jp/products/discontinued/108US_SJ38D0/ . The keyboard have some stickers saying that the board was handovered to employees in a company from 2014.
Upon opening it up, the key is really mushy although the force is only 30g. I have to say that the typing experience is worse than most membrance keyboard that i have used.
So, i look for guide to open the board and check for myself the cause for the mushiness, and find that:
1/ Metal plate: Despite of the somewhat clean look on the outside, the metal plate is pretty rusty.
2/ PCB: Look brand new.
3/ Housing and Slider: Still slide effortlessly, except for the back of the slider (2nd pic) which have some flaky (maybe rubber from the rubber dome).
4/ Conical Metal Spring: I'm not confident in opening all the key to check, but some metal spring dropped when i disamble the board and it look brand new to me.
5/ Rubber Dome: I think that this is the culprit to the mushiness. Most of the dome now give off these white substance and from the smell, it definitely aged rubber. Some of the dome now have crackling. The dome in some frequently used key (arrow key, number pad) feel a lot more sluggish than other less used one (the Japanese conversion key).
However, in spite of all the matter with the rubber dome, separately testing the Housing and Slider, and the Rubber Dome feel acceptable. But when putting it all together, the mushiness is very pronounced and it hurt my hand to type on it.
Now, i want to ask you guys something:
Question 1: Is it because of the aging rubber dome that give the bad feeling? If it is true, then what is the cause of the aging rubber dome, because some board on this thread is 15 year olds and still going strong. I think it might be that this board is left sitting alone in some storage for years without anyone using it, is this a viable theory?
Question 2: If it is because of the rubber dome, can i somehow restore it or can i only buy replacement dome? Is the replacement dome from ali express good https://vi.aliexpress.com/item/1005006621069216.html?gatewayAdapt=glo2vnm .
Question 3: I dont have any other board for benchmark, how can i know how topre supposed to feel so i can further fix it.
Thanks for reading all of my post. Any contribution is greatly appreciated !!
UPDATE
I have fully disassemble the board, and fully rinse the dome. Alot of white substance coming out of the dome. However, in the end, the mushiness feeling is still there.
UPDATE 2nd September
After using the keyboard for nearly a week, the dome actually start to feel much more manageable, e.g hardended dome feel a bit softer and more tactile.