[SOLVED] Two possibly fried backlit keyboards on newer PC build ?

[Ru1984]

Hey everyone, this is my first post on the forum and hopefully someone can chime in on what is going on with my newer pc build. A couple of days ago I setup a newer motherboard and other hardware which should be 10x better than my primitive ASUS p5k-e setup. The issue I'm having is that at the POST screen I get a "no keyboard detected" message as well as no backlights on the kb, it does however detect the mouse, drive and other hardware that is installed.

The keyboard was working just fine on my older setup so to make sure it was still working, I tried plugging it into my laptop which worked as well previously but now my laptop won't detect it. I'll admit that the keyboard wasn't 100% as it had a faulty cable, but I managed to rig it to work temporarily until I found a parts keyboard. Eventually I did find a parts keyboard and swapped over the cable via soldering but before I did, I tested the parts keyboard on my newer setup to see if it worked and low and behold it did which allowed me to continue installation of windows 10, that is until the 2nd time I powered it on it wasn't detecting even the parts kb.

I'm thinking the voltage on the usb ports is too much which is what fried my keyboards. Luckily the circuit board in the keyboard isn't complicated with only a few capacitors, resistors and fuses so I'm going to attempt to troubleshoot the components with a digital multimeter and replace any if necessary. Below is my newer setup. Thanks in advance.

Motherboard: Asus Prime X370 Pro

CPU: Ryzen 3400G with integrated graphics, Enermax CPU cooler

RAM: Samsung 8gb DDR4 x 4

PSU: Enermax Revolution Xt II 650w semi-modular

Storage: Samsung QVO 1tb SSD

 

[Ralston18]

One scenario being that the soldered cable fix only held for the test and then failed and/or caused some subsequent failure in another part.

= = = =

Make and model keyboard(s)?

Very much in favor of DIY repairs being cable and component swaps, etc..

However, many products are now made not to be repairable.

And even if one faulty component is properly replaced the next now older component in line may then fail....

I doubt that that the issue is USB port voltage being "too much".

Even if you find the applicable keyboard replacement capacitors, resistors, fuses, etc., test them, and solder them in correctly there is still quite a bit to go astray.

My recommendation is to get a new keyboard.

Better choice than risking the new setup on a glitchy keyboard, while frying itself, could likewise fry the host motherboard.

 

[Karadjgne]

Usb is 5v. That's it. Has been for years. Your motherboard isn't going to output any more than that or your mouse will blow too.

Faulty cable. That works both ways. As you say, there's not really much inside a keyboard but what there is is susceptible to voltage and amperage fluctuations just like any electronic component. A faulty power input can create resistance, which can raise the amperage draw and overload the smaller resistors, they are only 1/4w-1w at most, if carbon are 5% and metal film are generally 1% tolerance. There's also diodes, basically one direction resistors like a gate, and if power overloads those you'll get either nothing either way or a backfeed where you don't want power depends on if they are burned open or burned closed.

And that's assuming your soldering skills are adequate, only takes a touch between traces to ruin everything.

 

[Ru1984]

One scenario being that the soldered cable fix only held for the test and then failed and/or caused some subsequent failure in another part.

= = = =

Make and model keyboard(s)?

Very much in favor of DIY repairs being cable and component swaps, etc..

However, many products are now made not to be repairable.

And even if one faulty component is properly replaced the next now older component in line may then fail....

I doubt that that the issue is USB port voltage being "too much".

Even if you find the applicable keyboard replacement capacitors, resistors, fuses, etc., test them, and solder them in correctly there is still quite a bit to go astray.

My recommendation is to get a new keyboard.

Better choice than risking the new setup on a glitchy keyboard, while frying itself, could likewise fry the host motherboard.

The keyboard is an Asus G01 (see pic below) which came with the Asus G20AJ gaming pc. I purchased it used mainly for the backlit keys and volume knob. I don't know if this matters but the motherboard is also a previously owned unit purchased on eBay from a reputable seller. Could it be possible that the previous owner might have the BIOS configured in a way that is not compatible with this keyboard? I'm going to purchase a new keyboard and will update you on the situation. I appreciate the input Ralston, thanks!

 

[Ru1984]

Usb is 5v. That's it. Has been for years. Your motherboard isn't going to output any more than that or your mouse will blow too.

Faulty cable. That works both ways. As you say, there's not really much inside a keyboard but what there is is susceptible to voltage and amperage fluctuations just like any electronic component. A faulty power input can create resistance, which can raise the amperage draw and overload the smaller resistors, they are only 1/4w-1w at most, if carbon are 5% and metal film are generally 1% tolerance. There's also diodes, basically one direction resistors like a gate, and if power overloads those you'll get either nothing either way or a backfeed where you don't want power depends on if they are burned open or burned closed.

And that's assuming your soldering skills are adequate, only takes a touch between traces to ruin everything.

I see what you mean, my soldering skills are decent to be honest and successfully swapped the parts keyboard cable to my previously working kb and still nothing. Strangely enough though, the parts keyboard that stopped working, managed to work again when I inserted the faulty cable connector into the corresponding holes in the circuit board (not soldered) as the l.e.d's lit up again only to stop working once soldered in . I suspect the cable is 100% the culprit but what I don't understand is why the parts keyboard was working on my newer pc and then just stopped before I even attempted the cable swap. I think it's just bad luck plain and simple, one kb was bad due to the cable and the other has its own fault which I'm not sure what it is. Thanks for the input Karadjgne.

 

[Ru1984]

What's up guys, I have an update on the situation with my keyboard not working on my newer build. It never occurred to me to check the cables for continuity with my dmm but once it hit me, I immediately pulled out the multimeter and got to testing. It turns out that the d+ & d- wires on the connector had no continuity whatsoever, the rest of the wires are good so that brought my issue out to the light even more: bad cable! I already have a brand new one on the way, so I didn't mind it going under the knife. I cut off the section of the cable where the strain relief is, rewired it and checked for continuity again and it is now present. The parts kb cable checked out ok on all wires so I'm thinking the circuit board is bad on that one. I'll post the outcome when I plug in my new keyboard. Peace guys.

 

[Karadjgne]

👍

 

[Ru1984]

Update: I have my new keyboard plugged in and working flawlessly so all systems go. I was able to update my pc and install all the necessary drivers to have it running smoothly. I really appreciate the input and guidance, you guys rock, Thanks!

 

[Karadjgne]

Happy gaming 👍