Technics KN5000 problem


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Hi, I' m new to the forum and hoping that someone will be able to point me in the right direction. I just bought a cheap KN5000, knowing that it had a problem but thought I might be able to repair it. I'll try to explain it as best as I can and hope it doesn't sound too confusing.

Everything works as normal from the Ab(3) above middle C to the top end of the keyboard. Here's what happens below that, starting from C(1). The first 4 keys, including the black ones, don't produce any sound whatsoever. When the next 4 are played in turn, they sound their own note plus the one 4 below. For example, when I play E(1), it also sounds C(1), F(1) also sounds C#(1) etc.. The next 4 keys don't produce any sound when pressed but the following four again sound, along with the four notes which didn't produce any sound by themselves.

So, there is a pattern where the first 4 notes don't produce sound by themselves but are played by the next four as a discordant chord. It keeps repeating until G3 is reached after which everything is normal.

The first thing I tried was to reset everything to factory settings. Then I upgraded the software from version 5 to 10. (I had some problems initially with the Floppy Disk Drive but it seemed to resolve itself). I've checked all the connections inside and found nothing obvious.

Can anyone suggest a possible solution ?

Thanks,

Al.
 
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Welcome to the forum! :) What is your background in keyboard playing?

Gosh I bet that makes some interesting sounds when you try and play it! Where in the world are you? Did the upgrade change anything or was it all exactly as it had been previously?
 

happyrat1

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Try unplugging and CAREFULLY replugging all the internal connectors.

Just because they all look OK doesn't necessarily mean that they are not oxidized and causing an open circuit.

Unplugging and replugging a couple of times will allow the self wiping feature of the contacts to clean themselves.

A quick squirt of contact cleaning spray while performing this operation won't hurt either.

Gary
 
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Welcome to the forum! :) What is your background in keyboard playing?

Gosh I bet that makes some interesting sounds when you try and play it! Where in the world are you? Did the upgrade change anything or was it all exactly as it had been previously?

Hi Becky, thanks for the welcome. I've been playing (maybe I should say playing around with) keyboards for many years, varying from electronic organs to synths to digital pianos. I currently play a Lowrey organ at church, here in Florida but can't claim to be a very competent musician. Although I can read music somewhat, I tend to play by ear mostly and use the transpose function often, as I don't play in every key.

Yes, it sounds rather weird when I try to play this Technics keyboard but as it only cost me $25, I'm not too upset about it not working properly. The upgrade didn't make any difference that I've found so far. Probably if I had been upgrading a normal working instrument, there would have been some noticeable improvements but in its present condition, I'm not in a position to tell.

I've been emailing back and forth with Matti Sairanen in Finland and he has been very helpful with information and suggestions but I'm still no further forward. I would certainly love to get it back to normal as I believe it was a popular model back in its day. Maybe someone will come up with a solution eventually so for now, I'll hang on to it.

Regards,

Al
 
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Try unplugging and CAREFULLY replugging all the internal connectors.

Just because they all look OK doesn't necessarily mean that they are not oxidized and causing an open circuit.

Unplugging and replugging a couple of times will allow the self wiping feature of the contacts to clean themselves.

A quick squirt of contact cleaning spray while performing this operation won't hurt either.

Gary

Hi Gary, thanks for your reply to my post. Actually, although I did not state it earlier, I had in fact checked all the connectors by unplugging and replugging them. Having been in the phone industry for over 40 years, I'm fairly familiar with dirty contacts and oxidisation, etc. and they definitely did not appear to be suffering from that. I certainly appreciate your suggestion though.

One thing I did notice after I had posted initially is that the the left hand circuit board under the keys appears to have some corrosion. It seems to be under the coated surface of some of the thin circuit tracks, possibly caused by liquid being spilled on the keys. I've examined it carefully with a high powered lens and also checked for continuity and as far as I can see, the tracks have not lost their integrity.

However, if I use the KN5000 as a master keyboard and hook it up to another MIDI keyboard, the slave behaves in the same way as the master. This leads me to think that either the keybed or the associated circuitry may be the problem.

However, not being an electronics expert, I'm maybe going off on the wrong path. I'm hoping to possibly substitute a keybed from another of my keyboards at some point but this will probably mean having to cobble together some sort of patch cable. At least, that would let me know if my theory is correct.

Regards,

Al
 
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Okay, found the problem. It was a broken track on the underside of the keybed PCB which was going to a pin on one of the chips. Once that was bypassed, all the keys sounded just as they should - well sort of.

There seems to be an issue when playing some of the built in styles where some of the parts are at the wrong pitch. I can usually correct this by alternating between the Sound Group and Part Select buttons. This is fine when I'm just amusing myself at home but would be useless in any kind of performance situation. I'm going to try and do further research on this but if anyone is aware of why this is happening and can suggest a fix, please let me know.

Thanks,


Al
 
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Hi Al,

Welcome to the forum. I have no wisdom when it comes to keyboard repair but I must say your $25 Saturday Night Special sounds rather interesting and "avant garde".

It has clearly already been exceptional value for money in providing you with hours of amusement :)

Good luck and I hope you can sort out your 'board. Otherwise my only suggestion would be to send it the way of my old Yamaha SY22, which sits in the shed facing the corner and considering its actions...

Cheers,

Paul
 

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