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Korg B1 - specific notes don't work, problem with circuitry

Aloha all, I just purchased a Korg B1 digital piano with known issues. The keyboard sounds great but has specific notes that don’t work. Starting from the E after middle C, all Es, Cs and G#s don’t work.

Luckily, I found another ifixit post, the only place on the internet it seems, where someone understood why specific notes wouldn’t be working. Here is the link: ++"E" key and 3rd black key is not working.

I understand very little about circuit boards, but I was able to identify the problem immediately. C, E and G# receive and give inputs along the same path. There is an issue with the soldering on one of the *things* at the first E key, where the problem starts. See the images for this issue.

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So, one of my problems is that I don’t know anything about circuits or circuitry terminology, so I can’t even describe this issue, much less start to fix it.

Can anyone help me at least put a name to this, so I can start to go about fixing it? It seems like a basic circuitry issue that wouldn’t be hard to fix, but I don’t know where to start. Any help is appreciated.

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Not sure if @hakimj had resolved this fault?

da

@willcee

I don't know but @nathan_dixon_1993 had the same if not a similar problem and he solved it using the Chosen Solution.

See the post below the Chosen Solution

Click on the image to see how he bypassed the faulty track multiple with wiring between the keys.

da

Hi, I can't seem to find a way to open the piano.

How do you disassemble the piano?

da

@hakimj I just bought a Korg B2N (used) and I have the exact same problem! All of the C’s, E’s and G#’s not working.

Were you able to fix the problem?? If so did you do it yourself ? I am useless at this type of stuff.

Please and thank you!

da

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Soluzione Prescelta

Hi @hakimj

I’ve highlighted what I think may be the problem in the image below (or it certainly looks like it to me anyway). This is a zoomed in image taken from the 3rd image that you posted.

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(click on image to enlarge for better viewing)

It appears that there is an insulated jumper wire that connects between the diode that is connected to the key and the note multiple track where it comes from and goes to the next note. I assume that is all that it is as it has to span across other tracks without electrically touching them to connect the diode which is connected to the key and the track multiple connection to the other notes that share the same wiring path

I’m assuming that the notes you mentioned that don’t work are this key and the notes to the right of the key, is this correct?.

Looking at the other keys you can see the copper pad where the jumper is soldered to ( I assume that it is soldered) and also where the multiple track comes into the pad and then goes onto the next note in the particular wiring multiple, whereas on this particular connection it is not visible at all.

First you would need to use a DMM’s (digital multimeter) Ohms function, to check for continuity between the two blue arrows as shown in the image (I think that I traced the track OK - double check) and if no good, unsolder the jumper (in the red box) and check the pad and then measure between the two green arrows. It may just be a faulty track/pad/jumper connection.

If the pad has ”disappeared” or is too damaged to be fixed by connecting jumpers to it, then you can run an insulated wire from the diode connection (blue arrow on key - not too much heat as it may become loose ) to the diode connected to the key to the left (blue and green arrows are on diode) and then trace the track from the “missing pad” to the right to find which key (and diode) it connects to first and then run another insulated wire to it from the same place as the first wire i.e. you are effectively bypassing the damaged section of the track multiple so that the keys are all connected again. Hopefully this makes some sense

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@jayeff First of all, I am stunned that you responded withing 24 hours, especially as you are the very person I was referring to in my previous post!!!

That green arrow in the middle of the image is exactly the spot I was referring to - that's sitting right above the first key that doesn't work, and yes, certain keys to the right of that one don't work.

Thanks so much for giving me the terminology to describe this problem. I can take this info to a hardware/electronics store and get the tools I need to fix this. Your advice does make sense, and I'm super thankful!!!

You are amazing!

da

Hi guys.

I have a Korg b1 and the first 19 keys and the accompanying black keys don't make a sound. The rest of the keyboard works Just fine.

Does anyone have a clue what could be the problem here?

da

@stanislavt84493

Hi, I can't seem to find a way to open the piano.

How do you disassemble the piano?

da

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@jayeff You saved my ass! I had students all day yesterday, I went to teach in the morning. No sound on C,E and G#. Managed to take it apart and repair in between students! I didn't have my proper gear so it's a botch job but got me through and we are back baby. Thanks man!!

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@nathan_dixon_1993 hi please i have Korg piano with no sound in C E and G# could you help me pleaaase.

da

Very useful. I can't even figure out which screws to take off to get into mine. Taken all edge ones which others release the cover please thank you

da

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Hi @Stanislav Trandoski ,

I don't know the keyboard but with most there is usually a wiring connection between the boards to which the keys are connected and then a single cable back to the control board.

Normally there are 2 or 3 boards under/behind the actual keys and they are multipled together to reduce the number of wires that are necessary that go back to the control board.

Since the first 19 keys aren't working check the connection from the board that the keys are connected to and see if it is securely connected to the board next to it.

Here's an image taken from the image in the answer above this one, that shows what may be a connection point between two adjacent boards. The image does not show the connection on the top but I'm thinking that perhaps it is underneath the boards. I have highlighted the point of interest.

I may be totally wrong but that's where I'd look first and then look for any connections from the first board to the second board or to somewhere else.

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(Click on image to enlarge)

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Thank you for your prompt answer.

I checked with the multimeter and it seems that the connection is sound on that "bridge" between the boards.

That would be a nice elegant fix but now i'm stupified for what could be the problem.

Also, a couple of keys that aren't working are after that "bridge".

Here are the images of the device

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In the images, which direction from the "bridge" are the 19 keys that don't work and also the "couple of keys" that don't work?

Are they on either side or on the same side?

In the first image I can see a connector type soldering pattern on the left edge as well. Is there a cable attached to it?

da

@jayeff

Hi, I can't seem to find a way to open the piano.

How do you disassemble the piano?

da

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Tengo tambien problemas con un korg B1 no suena el Eb - G - y B algo conosco este teclado despues de los diodos de cada tecla se unen dea tres notas y envian la señal(pulsos) a los buffer triestados sn74lv125 y de ahi al cpu y tambien hay resistencias como en el teclado yamaha psr303_sm.

Revisare las resistencias despues del buffer triestado y cualquier cosa comento nuevamente.

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hakimj sarà eternamente grato.
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