What too look for to repair keyboard?

[Traijan]

Hi,
I have a broken Hyper X Alloy Elite 2 that I got from a local thrift store for $2 and it showed no signs of wear, was very clean and worked perfectly for about 3 months.  Then the number pad 0 key worked sporadically then the I key stopped working intermittently, then some  other key started acting up.
then another key stopped working intermittently.  I've since bought a Redragon keyboard that is functional to me (75% with a limited number pad) but I really miss my Hyper X board with the full 104 keys. 

One person told me that if it's multiple keys acting up that it is likely the PCB so I took photos all over the PCB so they were large enough for me to see small details and I checked for things like cracked or burnt solder joints,
or burnt capacitors (or what ever those little tube looking things are) but not being an expert, I didn't spot anything in any area of the board that looks different than any other area of the board.

Can't really afford a new one even if I could find one now that I'm on disability so would like to see if I can fix this one.  But if it's not repairable I'd like to find another board for under $100, I think the best way to express what I would want to buy is to say what I liked about the Hyper X BOARD.

• Really bright LED's so much that it almost felt like I was going to get a sun burn.  I need the RGB because I use my computer in dark rooms at night
• The sound of the red switches, It's why I'd been looking for mechanical keyboards at thrift shops and garage sales as I have neuropathy in my legs and hands and rely on the audibl0e noise to tell me that I've pressed a key as I've been reduced to one or two finger "typing" (I used to type 96 WPM with a .06% error ratio
• I rely on the ten key pad so need one of those
• Love the real Hyper X pudding key caps, really helps with my impaired eye sight using a solid color on the board, although I can pull of the key caps from my Hyper X to replace key caps that come on a non Hyper X board
• I'd like to have soft key presses as it's quite painful for me to type with my ReDragon as the keys bottom out fast & there is no dampening or flex in the RD keyboard
• i Really enjoy a heavy keyboard to stay in place on my desk and metal as it just feels good to me
• I now prefer having a detachable usb chord for the KB preferably with a pass through USB but I'm not married to having to have a USB port on the keyboard

Thanks for any info

[zegonix]

do you have access to a multimeter and potentially an oscilloscope? also for the repairs you probably need a soldering iron and usually for smd parts a magnifying glass or microscope is helpful.

first measure the resistance over the switch when activated. measure the resistance from mcu to switch (don't measure over the diode > on the diode side measure on the diodes pin connected to the mcu). if these all seem reasonable (<3 to 4 Ohms) i would probably try to measure the bouncing behaviour of the switch with an oscilloscope, to see, how long it takes for the signal to stabilise.

[Traijan]

Thanks, I do have a multimeter and soldering iron and nice large table mounted 10" magnifying glass surrounded by led lights.  but what is an mcu?  I am tempted to unsolder the I switch and solder in a new one then test it for a few days to see if the I switch continues or if it fixes it, I guess I was just hoping there might be something visually to aleret me on the PCB like when my laptop refused to charge and I found a solder joint discolored on the power port so replaced that and all was good again.
But yeah, what is a mcu?

Thank you

[zegonix]

mcu = microcontroller unit
its the intelligence on your keyboard.

[zegonix]

also, i implied it in my first answer but just to be sure i will say it explicitly: measure the resistance, don't use the beeping function.

[Traijan]

also, i implied it in my first answer but just to be sure i will say it explicitly: measure the resistance, don't use the beeping function.

Thank you for the info, much appreciated.