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Old 04-14-2018, 04:28 AM   #1
alindumitru46
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Default Corsair K70 RGB dead

In new times, new problems . It is understandable here, being a forum dedicated to repairs.
So my problem is with one Corsair K70 that I received from my brother-in-law.
Initially it started normally but after installing the Corsair software it started to trouble: keyboard lock, computer lock, restarts and finally dead...
I opened it and I found that there were a lot of coffee grounds
I thoroughly cleaned with a brush and isopropyl alcohol and re-assembled.
After 3 attempts to start, it was not recognized by any computer.
I tried to research but I did not have a chance, so I appeal to your guidance and advice.
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Old 04-14-2018, 01:02 PM   #2
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Default Re: Corsair K70 RGB dead

Tried checking the PCB(s) where the USB comes from? Coffee might've shorted something.
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Old 04-14-2018, 01:43 PM   #3
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Default Re: Corsair K70 RGB dead

Quote:
Originally Posted by alindumitru46 View Post
In new times, new problems . It is understandable here, being a forum dedicated to repairs.
So my problem is with one Corsair K70 that I received from my brother-in-law.
Initially it started normally but after installing the Corsair software it started to trouble: keyboard lock, computer lock, restarts and finally dead...
I opened it and I found that there were a lot of coffee grounds
I thoroughly cleaned with a brush and isopropyl alcohol and re-assembled.
After 3 attempts to start, it was not recognized by any computer.
I tried to research but I did not have a chance, so I appeal to your guidance and advice.
Are you sure it was coffee grounds? Cockroach feces look like coffee grounds too.
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Old 04-14-2018, 01:56 PM   #4
alindumitru46
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Default Re: Corsair K70 RGB dead

Mehhhh...Nevermind....
I just said I cleaned with isopropyl alcohol. Right now I'll upload some pictures.

LE: little troubles with uploading...
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Old 04-16-2018, 02:27 AM   #5
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Default Re: Corsair K70 RGB dead

Maybe start by checking wires between USB connector and keyboard's PCB. Then, when plugged into a USB port, make sure the keyboard is getting a steady 5V supply.
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Old 04-16-2018, 05:51 AM   #6
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Default Re: Corsair K70 RGB dead

Yep, the voltage is 5V at the terminals on the keyboard pcb, unfortunately I studied too little the NXP LPC11U3X datasheet to check the voltages.
Besides, I do not have so thin terminals to risk measuring pins.
And there would be a VRM, or something like that ...
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Old 04-17-2018, 08:51 PM   #7
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Default Re: Corsair K70 RGB dead

If the power and data lines are okay, then next check the input and output voltages of that SOT-223 voltage regulator.

If good, I would take the entire PCB out and give it a good wash with soap (dish detergent) and water. The let it dry completely and try the keyboard again.
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Old 04-18-2018, 11:54 PM   #8
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Default Re: Corsair K70 RGB dead

I would have wanted to sink the keyboard into such a solution and let it take some time to act on it, but I thought there might be some lubricant inside the contacts and it would be dissolved.
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Old 04-19-2018, 12:05 AM   #9
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Default Re: Corsair K70 RGB dead

Last night late, tired and in a hurry, I checked the VRM. It's a typically L1117S33 .
The measurements was made with both USB cables (keyboard and RGB) connected to the computer and the sockets on the keyboard's PCB.
The voltage on the input pin is ~ 5.1V, but the output voltage on the output pin quick tends to zero.
Hardly unpleasant ...
Is it relevant to measure the voltages only with the keyboard cable, ie without the RGB cable connected? Could there be any additional clue?
What happened and how do you explain that such a solid VRM can creep so easily?!

Last edited by alindumitru46; 04-19-2018 at 12:07 AM..
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Old 04-23-2018, 09:52 PM   #10
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Default Re: Corsair K70 RGB dead

Quote:
Originally Posted by alindumitru46 View Post
Is it relevant to measure the voltages only with the keyboard cable, ie without the RGB cable connected?
Yes, should be fine, unless the RGB backlight cable has some type of feedback (which I seriously doubt).

Quote:
Originally Posted by alindumitru46 View Post
What happened and how do you explain that such a solid VRM can creep so easily?!
It could be that there is something shorted on the output of that voltage regulator or it could also be that the regulator went bad (rarely happens, but not impossible).

If there is anything shorted on the regulator's output (you should check resistance from the regulator's output to ground with your multimeter), I would most likely suspect a shorted ceramic capacitor somewhere. Reason being is because ceramic capacitors like to become short-circuited when flexed or vibrated too much - something that isn't too hard to do on a keyboard PCB (think about all that slapping and hitting the PCB takes as buttons are pressed).

So if you do identify that there is a short-circuit on the regulator's output (I would say any resistance of less than 50 Ohms is certainly suspect), you should check the resistance of ALL the ceramic capacitors on the board. The ones that appear shorted should be removed until the shorted one is found (tedious annoying process, I know :\ ).
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Old 04-24-2018, 01:44 AM   #11
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Default Re: Corsair K70 RGB dead

Thank you @momaka, I'll try to check today all this.
Yesterday I searched for a VRM L1117 and found a LD1117ST C413 but I'm not sure that it covers the minimum requirements for the replacement part.
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Old 04-27-2018, 08:02 AM   #12
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Default Re: Corsair K70 RGB dead

0.857 kOhms is the resistance value of the voltage regulator from output to ground.
Capacitor values are here, but nothing under 850 Ohms.
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Old 05-02-2018, 12:47 PM   #13
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Default Re: Corsair K70 RGB dead

Quote:
Originally Posted by alindumitru46 View Post
0.857 kOhms is the resistance value of the voltage regulator from output to ground.
Capacitor values are here, but nothing under 850 Ohms.
Sounds like there is nothing shorted then and possibly only the regulator is bad. If you have a small breadboard, you can pull the 1117 regulator out, solder some leads to it, and built a basic circuit on the breadboard to test it.

Quote:
Originally Posted by alindumitru46 View Post
Thank you @momaka, I'll try to check today all this.
Yesterday I searched for a VRM L1117 and found a LD1117ST C413 but I'm not sure that it covers the minimum requirements for the replacement part.
Well, if your regulator really is a L1117S33 as you stated in post #9 above, then you need a 3.3V *fixed* voltage regulator. Technically, you could adjust an adjustable one to output 3.3V or "tweak" the circuit for a 1.8V fixed 1117 regulator... but for a direct replacement, find a 1117 with a fixed 3.3V output (usually you will see it labeled as 1117....33). As for the current rating - as long as it's in the same package (looks like SOT-223), it should be okay. Most 1117 regulators have a standard rating of 800 mA of current. You can also use a TO-252 part if that's all you can find and don't mind a small "bodge job" on the PCB. (Been there, done that... got a 19" LCD monitor working fine again ).

Last edited by momaka; 05-02-2018 at 12:50 PM..
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Old 05-02-2018, 01:36 PM   #14
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Default Re: Corsair K70 RGB dead

So why I was afraid, I did not escape ... To desolder that regulator from there is too much for me, that's why I did not insist too much. I'm trying to use the hot air station, but I have not worked for a while with it, and I'm afraid of destroying the pcb.
And the candy on the alms: one of my old monitors died; I'm going to post the problem with him too.
Thank you, again.
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Old 05-02-2018, 06:11 PM   #15
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Default Re: Corsair K70 RGB dead

Quote:
Originally Posted by alindumitru46 View Post
To desolder that regulator from there is too much for me, that's why I did not insist too much. I'm trying to use the hot air station, but I have not worked for a while with it, and I'm afraid of destroying the pcb.
No need for hot air then.
Just use two irons. One should preferably be rated for 50 Watts or more. The other 30-50W is fine. Flood the pins of the regulator with leaded solder with the more powerful iron. Then, heat the tab of the regulator with the bigger iron and use the smaller iron to alternate between heating the 3 leads of the regulator. Once all the solder melts, just slide the regulator away from its spot elsewhere on the PCB (looks like towards one of the white connectors is the best way to go). This is usually the tricky part, as there are other small SMD components around, and you have to be a bit more careful around those. But all in all, it's not too difficult. Maybe practice on another board for your first try. I thought of this method by myself way back when I still couldn't solder too well, and I was successful right from the first time without destroying anything. Of course, I practiced on a dead board first.
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Old 05-03-2018, 02:09 PM   #16
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Default Re: Corsair K70 RGB dead

I know, you told me this from the first posts, about 2 years ago
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Old 06-05-2018, 11:26 AM   #17
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Default Re: Corsair K70 RGB dead

Hi there,
After many, too many days, when I did not get to the place where I have my little workshop, I had a way up there today and I got my heart on my teeth and I replaced that vrm. Very easy, just with 1 iron and a lot of flux.
Because I kept some of the experience gained over time, I managed to desolder but also the soldering almost perfect. I cleaned with IPA at the end.
I put that one ST LD1117 C413 because I did not have another one ready.
The voltage measured after that on pin 2 is Vout=5.07V and on pin 3 Vin=1.343V
Still not working and no lights .

Last edited by alindumitru46; 06-05-2018 at 11:44 AM..
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Old 06-09-2018, 03:30 PM   #18
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Default Re: Corsair K70 RGB dead

Quote:
Originally Posted by alindumitru46 View Post
I put that one ST LD1117 C413 because I did not have another one ready.
The voltage measured after that on pin 2 is Vout=5.07V and on pin 3 Vin=1.343V
Still not working and no lights .
That's not right.
Your V_out pin cannot measure higher voltage than your V_in pin. Either you're measuring something incorrectly, or there is something very wrong with the circuit. Try re-taking those measurements again, and make sure you are measuring the correct pins.

Also, like I mentioned in post #13 above, you cannot use any 1117 regulator you like - it has to be one with a *fixed* 3.3V output. If you use a regular adjustable 1117, then you have to add a resistor network on the ADJ pin to set the output voltage at 3.3V. Otherwise, it's not going to work.
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Old 06-10-2018, 03:26 AM   #19
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Default Re: Corsair K70 RGB dead

I wrote the message from my cell phone and I tangled Vin with Vout. And I could not even correct it.
I actually realized that you are right about using another type of vrm, different from the specified one.
It's hard to find quickly that vrm with a fixed 3.3V Vout. I await the moment when someone to make an order to put that vrm, which nevertheless has an insignificant cost of $0.45.

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Old 06-17-2018, 11:20 AM   #20
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Default Re: Corsair K70 RGB dead

Well, if the replacement 1117 regulator you have now is an adjustable one or fixed for 1.8V, you can turn it into a 3.3V regulator with a few small resistors. A picture of it would help to see what it is.
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