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[Solved] CTK-3000. One key deactivates touch sensitivity in some others


bepo12

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Hello,

 

I have a CTK-3000 keyboard which has an issue with the touch sensitivity.

When I keep pressed the 3rd G#, it makes the following 7 keys, until D# sound super loud. If G# is not pressed, all those keys sound normally.

If a do it in the reverse way, I press first any of these keys and then I press the G#, it also works normally. But if then I add a 3rd key, this one sounds loud again. So G# is the one that produces the other give loud sound.

 

It happens both with touch sensitiviy level 1 & 2. If I remove the sensitivity, everything works.

 

It really seems to be a defect on the PCB (electronic board). If disassembled almost the hole keyboard, but it is difficult to discover the possible failure if I don't know exactly what am I looking for.

 

I've seen this issue in another keyboard, but the suggested solutions (replace the keyboard) is not available for me.

Although my keybord is brand new, it has been stored in a warehouse for years, so it is out of warranty.

 

Is there any way to fix it by myself?

 

Thanks,

 

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While  your problem could be a bad circuit chip or a defective ribbon cable connector, problems like this are often caused by dirty or corroded key switch contacts.  You will find a set of dimpled rubber contact strips under the keys.  Try lifting these off and cleaning the pc board contacts and the insides of the dimples with rubbing alcohol and cotton swabs.  Do not use any other solvent, or anything that contains water, and be very gentle with your cleaning action.

 

Good luck !

 

Regards,

 

Ted

 

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Hello Ted. Thanks for your advice. I've disassembled the hole keyboard and I've removed some dust, but unfortunatelly, the problem persists. I've discarted a rubber strips issue, as I've switched its position and the problem keeps at the same key.

 

After that, I've been checking the board around the affected zone and I've discovered a welding mistake (attached picture), which can be the origin of the problem.

 

Tomorrow I'll repair this welding. I'll let you know if it has worked or not.

 

Thanks!

20170304_110609.jpg

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Glad you got it sorted and that you now have a working keyboard, but that means that the problem had to exist since you bought the keyboard.  There is no way that solder would have flowed from one connection to the other at room temperature, and if that circuit chip had ever got hot enough to melt the solder, it would have been fried.  I'm surprised you did not notice the problem back then, but all's well that ends well.

 

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Yes, of course it was a manufacturing defect. But I bought this keybord last week. It had been stored for years in a shop and I got it at good price (I think!), as it was brand new.

I noticed the problem in the first day I had it.

But as you said, all's well that ends well.

:)

 

Thanks!

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Wow, glad I saw this-I've done alot of repairs including many soldering projects. Word to the wise-sloppy soldering isn't your friend, and apparently can come out of the factory like this! One tiny solder bridge created all this havoc, and fortunately didn't short this hard to replace SMT chip. Never assume everything has been put together properly! I have repaired several keyboards simply by opening them, and refitting a loose cable or connector. It happens.

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Yeah, Johnathon, I was studying those pics yesterday.  I think we are looking at the bottom (non-component) side of the board.  From the looks of those 6 or 7 or 8 leads coming through from the top side, it appears that the top side components were floatation soldered, but those 3 or 4 diodes here on the bottom side could not have been done that way.  I am betting that they were manually (human) mounted and soldered (oops !) after the floatation process.  So much for quality control testing !

 

 

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  • 3 years later...

An ancient thread and the OP undoubtedly long gone but I had to reply and say thanks as this has helped me to repair a keyboard I’ve had knocking around for years. It’s haunted me because I was just too idle to send it back when it was under warranty. It’s the first time I’ve done something like opening up a piece of kit and fixing a soldering error so feeling mightily pleased all round.

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  • 1 year later...

I have the same issue, CTK 3400SK out of warranty, but mine is the F#3 key. Whenever I press F#3 without releasing it, all neighboring keys from C3 to G3 doesn't seem to sound right. It sounded loud, no matter how soft I pressed these keys. But whenever I release F#3, everything goes back to normal. It sounds annoying playing your keyboard with this issue. I have tried dismantling the entire keyboard, checking, finding what caused it, cleaned and removed the dirt as per advised by the previous forums and youtube videos. I just cant find what caused it. What could probably caused this issue? I just love to have the touch response feature because it helps us express better the music we are playing. Thanks.

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Revisit the last post-about the defective solder "bridge" that was causing the problem after all. since the CTK 3400 is a slightly older Casio-I am wondering out loud-if this defective solder bridge could be causing the same problem. Look for other components like this-where there might have been a sloppy solder joint that is across two terminals that should not be soldered together-which would be almost all of them. And make sure every screw attaching the IC boards and keyboard assembly are tight-if even one screw is loose-could be ending the IC board slightly when pushed down, and causing a short or broken IC trace to open up-even a hairline crack could do this. I know this is true-I just repaired an RC transmitter that was malfunctioning and traced it to a tiny crack in a circuit trace-bridging this trace back together fixed the problem.

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  • 1 year later...

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