Anyone know what type of RGB LED is used on Keyboard light strips

Rectro33
Rectro33 Member Posts: 23 Member

Hi


One of my LEDs is gone on the first key for my S88 MK2 anyone know what type of led it is?


Thanks, Dan


Comments

  • mickeyl
    mickeyl Member Posts: 58 Helper

    Pretty blurry, but it might be a WS2812.

  • Rectro33
    Rectro33 Member Posts: 23 Member

    Thank you, also found something similar to what you mention so looks like I maybe on the right path. WS2812B-4 There seems to be so many variations. When I take it apart again to put the Aftertouch strips in Il take some better images.


    Thanks, Dan

  • D-One
    D-One Moderator Posts: 2,879 mod
    edited February 22

    That looks a lot smaller than a typical WS2812B, you might want to take some digital calipers and measure it to make sure you buy the right or compatible led, also I don't see any resistors next to the led, check if the PCB has them somewhere else, some led's have build-in resistors.

  • Rectro33
    Rectro33 Member Posts: 23 Member

    I found this picture on my phone, does this help any more?


  • D-One
    D-One Moderator Posts: 2,879 mod
    edited February 22

    Do you have experience soldering surface mount components this tiny? I really don't advise it, I'd just take the PCB to an electronics repair shop

    Hard to be sure if it's 5v LEDs with resistors or 3.3v, using a multi-meter to test would be the right move.

    For size based on shape and pic, I'd say it's between 0804 and 0810 but there's so many sizes it's near impossible to know without calipers.

    Maybe this little bugger: https://www.made-in-china.com/showroom/bosmfc-lj/product-detailkXYxtKadgupo/China-0807-Flashing-SMD-RGB-LED-Light-Top-Mount-Small-Size-RGB-SMD-LED-Diode.html

    Try asking HW support, although I doubt they will answer. Again, I'd just let someone with experience handle it. If I remember correctly the KKSmk2 works fine without the LED PCD (in case it stays for fixing for a week or two)

  • Rectro33
    Rectro33 Member Posts: 23 Member
    edited February 23

    Thanks for your advice and help. I have soldered crazy small things, but am not as versed in electronics as you are. When I take it apart I will take some proper clear pics, and measure it. Luckly the one that is not working is right at the beginning so there is less chance of me effecting more next to it. I dont know of any services that do such repairs, never needed it before. This strip of leds is split into 3 boards that clip together (pic bellow). If I could source the left board id just replace that. As for multi meter, I have one but wouldnt know what pins to put it on to test it.


    Thanks, Dan

  • D-One
    D-One Moderator Posts: 2,879 mod
    edited February 23

    I have some hi-res pics of the internals in some external HD, can't find it atm.

    I'm not some sort of expert, I've used LEDS in DIY electronic projects before but take anything I say with a big shovel of salt, I only know the very basics. Any repair shop that does electronics should do this for you, sometimes it takes some convincing in such small jobs, you gotta Google shops in your area... Lead-free solder that size looks like a nightmare to deal with.

    I'll tag @reffahcs he knows way more on electronics stuff than I do, maybe he can help.


    As for multi-meter, I have one but wouldn't know what pins to put it on to test it.

    I think you just put one probe in one of the 4 random corner connections, then the other probe in the other 3 until you get a voltage reading meaning you found a cathode and anode. here: https://www.etechnophiles.com/test-an-led-with-a-multimeter/ but go confirm it with an expert, I don't want you to burn your whole PCB over something stupid I might say.

  • reffahcs
    reffahcs Member Posts: 840 Guru

    Thank's @D-One for the tag.

    So in cases like this where you have unmarked components, surface mount capacitors, inductors, resistors, leds etc... you have two choices, option 1 is to try and find a schematic or service manual for the device so that you can find the actual part number. option 2 which is more often used because schematics are usually hard to find for newer equipment, is to use a donor board, ie a sacrificial device that is the same as the one you're attempting to repair.

    The issue you'll have with finding a single replacement LED from someplace like Mouser or Digikey, is that even beyond finding the right size, you'll need to find one with the same pin out and the same forward voltage and rated for the same current. That's going to be hard if not impossible to determine without knowing the actual part number. If you get it wrong, best case you'll have one LED that's a lot brighter/dimmer than the rest, worst case it will burn up in a few minutes and you'll be back where you started.

    Personally I would look for a used if not broken S49 or S61 MK2 off eBay or Reverb and use that as a source for the LED. Plus you'll have the added benefit of having it for additional parts to repair your MK2 for the foreseeable future. I checked eBay and price wise the S49 and S61 were similar, going for about $300 at the cheapest. Might as well go for the S61 as it has more parts? If the keybed is different for the S88 ie weighted/semi-weighted, then you may want to opt for a used/broken S88 MK2 so that you can make use of the keys as well?

    Hope this helps, I wish there was an easier way. If you want an idea of how repairs like this (without schematic, part information) get done. Check out this guy's channel on YouTube:


  • D-One
    D-One Moderator Posts: 2,879 mod
    edited February 23

    You can figure the fitment part by looking at mousers 3d models or in PCB design software (called footprint), google images too and, after removing the broken led you can look at the PCB itself, that part is not the hardest as it doesn't need to match 100% as the solder can flow a bit to make the connections but avoiding burning an led or having too bright/dim will be hard... There's also just 4 possible positions of pinout, so at worst it's 4 tries 😅

    I guess you could buy a handful of different ones and test it on a Arduino cheap microcontroller to compare brightness but, since surface mount stuff can't be used on a breadboard it will be quite challenging to solder the 4 wires to connect to the microcontroller, not impossible tho.

    Honestly, I can't wait till the EU forces every company to share this type of data publicly, service manuals and schematics... It's not like MIDI keyboards have some sort of secret tech that is gonna be stolen by other companies, it's basic stuff, no reason not to share.

  • reffahcs
    reffahcs Member Posts: 840 Guru

    Yeah the size isn't the most important aspect, it's mainly making sure the forward voltage and current rating is correct. And you're correct, it's not impossible to think you could find a match by browsing through the catalogs of Mouser or Digikey (personally I prefer Digikey, but I'm also east coast). I suppose it just depends on how much your personal time is worth, and how motivated you are to find a match 😅

    That being said, the reason I suggested main reason I suggested the donor board is because if you're gonna shell out $200 or so to have some one repair an LED, then I'd want to be absolutely sure that I'm giving them the correct part. Now if you're doing it yourself, then it's probably not that big of an issue if the LED goes poof as soon as you power on.

    For what it's worth, the Quick 861DW hot air station is less than $250 on Amazon currently if you wanted to try and give it a go yourself. Set to 350-380C, add a little flux to the LED, gently heat until solder flows. If you're in a country where you can get leaded solder, it helps to mix a little of that with the existing solder since it's most likely lead free which means it melts at a higher temp.

    Best of luck, feel free to DM me or reply here for more help.

    Cheers

  • reffahcs
    reffahcs Member Posts: 840 Guru

    Yeah it would be nice if we could get simple part numbers like this from NI, or any vendor for that matter.

  • Rectro33
    Rectro33 Member Posts: 23 Member

    Thank you I read all your answers, they are very helpful. I managed to get a better picture of LCD 1 and 2, seems they are different. The one Im replacing is LED 88 which is not as you would expect being the bottom first key. I have already had to buy a Fatar LT100LR keybed just to get the aftertouch strips from it. If the led are the same on a cheaper MK1 keyboard I may try that. I should have sent this keyboard back as its caused me one heck of a headache since I got it second hand and smoke ridden.


  • reffahcs
    reffahcs Member Posts: 840 Guru

    It's possible the MKI and MKII share the same LEDs, wouldn't be the first time. Hard to say though with the chip shortage situation still not fully resolved. Is LED1 the LED for the first piano key? Interesting that they look different.

  • Rectro33
    Rectro33 Member Posts: 23 Member

    LED 1 is the very last key on the 88 note keyboard AND LED -2 is next key down. The first key on the keyboard is LED-88.


    Dan

Back To Top