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R500: "Ghost" keypresses on the "g" key

R400/R500 series specific matters only
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glossywhite
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R500: "Ghost" keypresses on the "g" key

#1 Post by glossywhite » Mon Oct 24, 2016 7:06 pm

Hello :)

You may recall that I purchased a used R500 a couple of months ago? Ever since day 1, I get spurious "ghost" keypresses of the "g" key... it's happening now as I am typing. Shining a bright LED torch between the keycaps doesn't reveal anything much as regards excessive dirt or crud etc, so it's probably something causing a short at dome/contact level on the membrane. Does anyone know how to disassemble an R500 keypad so that it may be cleaned? Yes, I know a new keyboard isn't THAT expensive, but I am of the ilk that if I can effect a repair for free with my myriad hardware/software skills, I shall do so FIRST before rolling over and buying a replacement.

Thank you! :) God bless, Matthew.

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Re: R500: "Ghost" keypresses on the "g" key

#2 Post by rkawakami » Mon Oct 24, 2016 7:39 pm

It sounds like the conductive rubber dome may have become detached from the keyboard. However, before you do anything which may cause damage to the keyboard, I would remove the entire keyboard from the system and then re-attach it; in other words, do a re-seat of the keyboard connector. Also, while it's removed from the system, you might try blowing some compressed air across the keys. It may not solve your issue, but it would be a good time to get rid of some of the "stuff" under the keys.

One other thing to check is to see if the trackpoint cap is not pressing up against the key. Remove the red cap and see if the problem goes away. If it does, get a new one.

The conductive rubber domes are normally glued in place and therefore should prevent anything from getting inside to affect the switch contacts. My suggestion would be to carefully lift off the keycap and see if this is true. However, you stand some chance of breaking one of the tiny pins/tabs which keeps the keycap connected to plastic hinge assembly. Unfortunately I cannot tell you exactly in which direction you need to pry the cap off. In the past I have lifted the back right or left corner up but this could have been due to the specific design (i.e., manufacturer) of the keyboard.

Assuming you get the keycap off without damage and you do find a loose rubber dome, clean the inside with a dry cotton swab (don't use any alcohol-based fluid), clean the contacts on the keyboard, temporarily put the rubber dome back in place and verify it still registers each depress. If okay, put a tiny amount of superglue around the edge of the dome and glue it back on the keyboard. Give it time to dry and then push the keycap back onto the hinge assembly.

If you find that the dome is still glued to the keyboard, then you need to decide if it's worth pulling the dome off the keyboard.
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glossywhite
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Re: R500: "Ghost" keypresses on the "g" key

#3 Post by glossywhite » Mon Oct 24, 2016 7:59 pm

rkawakami wrote:It sounds like the conductive rubber dome may have become detached from the keyboard. However, before you do anything which may cause damage to the keyboard, I would remove the entire keyboard from the system and then re-attach it; in other words, do a re-seat of the keyboard connector. Also, while it's removed from the system, you might try blowing some compressed air across the keys. It may not solve your issue, but it would be a good time to get rid of some of the "stuff" under the keys.

One other thing to check is to see if the trackpoint cap is not pressing up against the key. Remove the red cap and see if the problem goes away. If it does, get a new one.

The conductive rubber domes are normally glued in place and therefore should prevent anything from getting inside to affect the switch contacts. My suggestion would be to carefully lift off the keycap and see if this is true. However, you stand some chance of breaking one of the tiny pins/tabs which keeps the keycap connected to plastic hinge assembly. Unfortunately I cannot tell you exactly in which direction you need to pry the cap off. In the past I have lifted the back right or left corner up but this could have been due to the specific design (i.e., manufacturer) of the keyboard.

Assuming you get the keycap off without damage and you do find a loose rubber dome, clean the inside with a dry cotton swab (don't use any alcohol-based fluid), clean the contacts on the keyboard, temporarily put the rubber dome back in place and verify it still registers each depress. If okay, put a tiny amount of superglue around the edge of the dome and glue it back on the keyboard. Give it time to dry and then push the keycap back onto the hinge assembly.

If you find that the dome is still glued to the keyboard, then you need to decide if it's worth pulling the dome off the keyboard.
Hello :)

Thank you. The first thing I did after buying this was to buy a new TrackPoint rubber - the one supplied was worn and split, and didn't fit the square black plastic post properly. I have a new one now - I just removed it and pressed VERY lightly on the square black post around which the TrackPoint rubber is seated... I got "ggggg..." on the keyboard, and literally now I am pressing fairly firmly, DIRECTLY downward on the re-fitted rubber and it's "ggggg"'ing again.


[update]

With "g", "h" and "b" (keys that surround TrackPoint) keycaps REMOVED, this triggering does not occur at all! There's some compressed dust surrounding the scissor mechanisms, so I'll clean that away to see if it helps (I can't see how that would cause it... odd.)
gggggggggrrrrrrrrrr

glossywhite
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Re: R500: "Ghost" keypresses on the "g" key

#4 Post by glossywhite » Mon Oct 24, 2016 8:42 pm

Whoops! That was a bit silly, now I've broken off one of the TINY nylon pegs on the "T" key scissor... ah well, it works even if it wobbles a tad, haha - I think I shall just invest in a new keyboard and quit trying to cut corners :p

Thanks for your help :)

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