CORSAIR K70  VENGEANCE KEYBOARD LED FAILURES (BLUE) ?     p/n ch-9000045na   Circa,  2014  

First some facts:  (I do love this board, I can type real fast on Cherry KBD of any kind)
I just love all Cherry based MX1 keyboards,  
the LEDs from China are CRAP,  die fast , not in 20 years, but days. 20 days.
The keyboards all fail for bad blue LED's (not other colors) LED's   , in my case 1 LED fails every month..  Ive now done 20 or more, all mine last. proving CHINA parts stink.
Not one main PCB failure, not one bad solder joint etc, only the LED's, discrete failed ! < FACT .
These facts tell  you, the Blue vendor (unknown) of LED made junk LED'S, And the fact that Corsair dropped this version of board. (vary telling that) and fact 2, my Liteon LED's just work. (from top seller/distributor of descrete parts.

I removed the bad LED's (most were dead open, the diode inside LED  not connected or blown open ,some were only very dim and not one was shorted out.)
I bought 50 new, spare  LED's at " LITEON 859-LTL17KTBS3KS--------Blue/ Water Clear "  (slightly brighter than origional) Fact 2, after running my new LEDs for 8 month , not one failed.
They are polarized DIODES, so put them in  correctly, Anode to Anode hole, or they will be dim or be dead.
From the bottom side, most long lead LED go to the left side,  long (Anode). the Skinny traces is Plus anode long lead.
The LEDs are modulated , not run on pure DC power. (this allows easy dimmer controls)
My X key is still bad, this is not the LED failing, but the driver, ? or somthing (ESD?) I didn't try to find out. (lazy)

Myth one debunked, "all key switches need to be de-soldered to get, one key out." False ,see photos below for proof  , 1st de-solder LED, and 2 switch pins, and trip 2 locks on switch top, and it's out. (next to the word Cherry and 180 deg from there.)
I have Cherry MX1a-E1NN spare switches, on hand, but don't need them ,yet. They have 2 million stroke life spec.. so... hard to wear out.
You only need to remove the  36  keys caps shown,  to remove the 22 TOP screws total, ( leave 4 until last, see photo 2 below)  Big time saver that. Why do excess work?,or damage ribbons.

The CORSAIR logo needs to be removed, (peeled off) to get 1 screw and 1 more hidden screw, at  small cover top right corner, right of speaker volume.
See the 4 leave screws in Photo 2:, then pull the bottom cover off keyboard.
Leave the cord attached and its holder/carriers.
Then remove the 4 screws (left before) if an only if needing to access those rear function keys.
It's a nice keyboard, too bad, we can't buy new key caps from this maker, but after market does sell MX cap keys (like maker Rosewill) but none have transperent letters, to make the LED work.  (I hope that changes, in the future)
With my page, you can fix 1 bad key in 1 hour. or 1 LED. (not 20 hours, as others say)  I'd wait for 10 to fail and do it.
End report. (It is hard work repairing,  but I will never pay  $150 up for new keyboard, once bitten ,twice shy...)  All work done using ESD protective straps. (and tools)

Photo 1 , shows, keys to remove and 2 hidden screws.  (20 TOTAL) 4 more if carrier must be pulled. (but do so last ;work the upper bank of LED last)
The right screw top is under this tiny volume control cover that pops off, . To right of volume control  (pry only from right side of volume to left of cover and it pops off not too easy, it must come off and this screws.

Photo 2:  Leave these 4 screws alone until below.only if necessary to remove and very  last of all.
The bottom comes off , with these, 4 screws funcion keys row, left in place. This method also protects the ribbon cable underneath from damage.

If all top screws but in red are remove the bottom pan full straight off. If resistance is felt doing that, a screw above in YELLOW was skipped.  I think 20 Yellow marked  screws.
I leave the RED screws in place so no damage happens to the inside CARRIER board as the bottom is dropped of.

Photo 3: Leave all cables connected, unless necessary.
If the carrier board, bottom of below photo,  hides bad keys or LEDs, then take off the USB carrier board LAST. do that row last.)
 Below I'm getting ready to remove cables and go under the black plastic CARRIER.

Photo 4,  The LED JOB,  or switch, but switches never fail, not one in 4 years.
Do not heat a pad over 3 seconds. (pretinning the pad helps with real 60/40 solder (resin core)) then it sucks out 10x more easy.
Only takes 2 pins to get the LED out, all 4 pins must be sucked dry, and LED out to get the switch out.
Example 1 is below, Switch out.
 I solder sucked out 4 pins on ESCAPE key, LED first, then 2 switch pins, then trip the 2 switch locks and bam, out drops the switch.. Macro Photos, nice and clear.
Below see the  2 LED pads.  I sucked only those 2 pins with a solder sucker iron, and replaced over 25 LED now. (42 LED now, done in 3 long  years.)
 Long LED leg, goes to left in most cases , to the daisy chained trace. (see that)?  A= Plus + = Anode.

Photo 5:
The switch locks to the  alum. panel.
(]LED out and 4 pins de-soldered) trip the top switch  locks, then at  bottom tap on the switch with tiny screw driver  and out it comes. Any switch comes out, no magic, or other tricks, but you do need to know how to de-soldered and not damage it.

Photo 6,  I moved the ESC LED to the bad , Tilde key ~ below as a fast test.. Bingo it glows,  In every case, keyboard was good, but LED blown open inside or weak. I don't think it's ESD related.
Dead letters are:
F5 , ~, 2,8,},D, J, K, X ,N ? Pause, back space and E.  (1 month old and these LED died)
One year later 9 more LED fail, but  only the origional LEDS fail NEVER MINE,  (damning facts)
I also ran the LED low brightess for one year, and still they fail. (so its not about LED current is it ! no, it's about quality from China stinks.) As you see , only techs know these facts after repairing it...

All comments herea are In my personal opinion and all photos here, are my work, and all tests are my own.
I don't really need LED's, but was very curious at to why it failed? With lots of free time on hands, and vast tools.

OEM photo is here:  A Stock photo.... with the red gamming key upgraded, I don't do 1 to 6, ever. just W,S,A,D.

After 3years  of use , I wore  off the paint on some keys and repainted then with black enamal   (model paints)  I'm rebuilding this board every  year now... then to the grave !
One trick is to get white letter stickers,  put them on the key then paint it. (and when dry remove them) 1/4 is is made by    Headline Sign 31742 Stick-On Vinyl Letters and Numbers White 1/4-Inch  (below 1/4" is hard to find)
Then I used and exacto knife to cut new letters in my painted sections. (crude but I do not care) Only clean and 100% functional matters to me.

rev 3   ++++1-12-2015  (retired electronics tech)   Total number of LED that failed to date, 42.. (not one new LED I replaced  failed ! in 3 long years.)