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Keybed: Strange rattling sound, D4 only
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Klosterbruder



Joined: 25 Feb 2020
Posts: 3

PostPosted: Wed Apr 22, 2020 7:33 am    Post subject: Keybed: Strange rattling sound, D4 only Reply with quote

Hello there from Germany! Wink

Kronos2-88, bought about two months ago.

Please have a look: https://www.youtube.com/watch?v=NCRmvLr6CD8

German comment tells that the rattling sound doesn't occur if hitting the key diagonally from right to left, but if pressed down vertically or diagonally from left to right. Erm - hope I could make myself clear; more or less. :/

It's just the D4 key affected, all other keys behave properly. Might feel like a tiny issue, but it's real disturbing - like a stuck pixel of an LC display always drawing your attention. And it's D4, not A0, thus there's permanent nuisance while playing.

I already spent hours with browsing YouTube and this forum, but didn't find any solution, don't even know if it's a known problem or a completely new one.

Of course I already contacted the seller, which is Thomann; they offered to exchange the Kronos with a new one.
But I still hope there's a simple fix as I am not that excited by the exchange idea: Could mean two or three weeks without a Kronos (a real tough situation), my display has no pixel defects (new one might have), KaPro EXs 19 already registered to my serial number; and I already regard my Kronos as a kind of personal instrument I just don't wish to wave goodbye to.
In addition, I sent an eMail to the German Korg subsidiary, but no reply, yet.

So; any ideas? Wink
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GregC
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Joined: 15 May 2002
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Location: Discovery Bay (San Francisco Bay Area)

PostPosted: Wed Apr 22, 2020 1:01 pm    Post subject: Reply with quote

the problem won't go away. I wouldn't want it - esp when Kronos is $3000 +

And if in 3 years, you decide to sell your K, you should disclose its flawed.

So your resale value is not good.

All new boards should be perfect.

exchange it. I wouldn't have any hesitation.
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Jogger



Joined: 23 Dec 2016
Posts: 26

PostPosted: Wed Apr 22, 2020 1:16 pm    Post subject: Reply with quote

I had a similar problem with mine. I suspect it was due to rough handling. Came across the country via UPS. Left on my driveway without getting notified which I requested. Returned it. Another was sent from a state next to mine. Delivered the same way, no notification in driveway. Anyone could of taken it or got rained on. Anyway, new board no problem with keys. I'd definitely return it.
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average_male



Joined: 07 Feb 2011
Posts: 46

PostPosted: Wed Apr 22, 2020 4:01 pm    Post subject: Reply with quote

Three options, as I see it:

1) Return is your best option. You sound a lot like me, the little things bug the heck out of me. You pay top dollar (Euro, in your case) and you should have top quality. This is factored into the cost of the new Kronos

2) Open it and adjust the spring plate by removing the key and placing it back. Not a great option given warranty considerations

3) Manual external adjustment of spring plate (this assumes the spring isn’t seated correctly): there is a process for “aligning” keys, you can try this approach as it may seat the spring plate back in its correct position. This process involves wedging a screw driver or similar between the keys and pushing the offending key to either left or right. This process may seat the spring correctly. Or before shipping it back, trying pressing/hitting the key with a bit more force than normal, this too could seat the spring in its correct resting position.
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Klosterbruder



Joined: 25 Feb 2020
Posts: 3

PostPosted: Thu Apr 23, 2020 5:49 am    Post subject: Reply with quote

Thank you for your anwers - and condolence. Smile

GregC wrote:
the problem won't go away. I wouldn't want it - esp when Kronos is $3000 +
And if in 3 years, you decide to sell your K, you should disclose its flawed.
So your resale value is not good.

Oh, I don't care about the resale value of musical instruments; I keep them all or give them away for free. No, I am no rich man, not at all. But musical instruments are a bit like books - keepers and lifetime companions. Wink

Jogger wrote:
I had a similar problem with mine. I suspect it was due to rough handling.

MIGHT be a similar case here; the impressively large box looked like it came directly from a war zone, albeit fine on the inside. But I didn't notice any D4 flaws for two months, so I guess rough transport handling might have promoted but not really caused the problem.
Maybe the Kronos just feels offended by the presence of my old (t)rusty Triton Extreme residing ABOVE it. (In Germany, the term "workstation" is of female gender.) Very Happy

average_male wrote:
Return is your best option. You sound a lot like me, the little things bug the heck out of me. You pay top dollar (Euro, in your case) and you should have top quality. This is factored into the cost of the new Kronos

My father is a stereo enthusiast, running audio equipment worth a family home; no exaggeration. Many regard him as crazy, even more regard him as totally nuts, I regard him as being right as he says: "Wenn mir etwas Tag für Tag immer wieder Freude macht, ist der Preis gerechtfertigt." - If something makes me happy day after day, it's absolutely worth it's price.
That's how I think myself; on a minor scale. Wink So I slowly save up money untill I can buy the best of it's kind, making me smile every day - instead of buying a cheaper one, making me think 'Sh... I should have bought the better rig.' every day.
That rattling won't make the world stop rotating, but it's like spotting a stuck pixel of an LC display: As soon as you get aware of it, it's a permanent nuisance, practically focusing your attention. Similar with this D4 issue.
So you also suspect the flat spring being the culprit? That'd also been my first idea. Thus I'll try the external approach you suggested - and if that doesn't help, I'll turn my dining/music room into an operating room.

Thank you!
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Klosterbruder



Joined: 25 Feb 2020
Posts: 3

PostPosted: Thu Apr 23, 2020 9:25 am    Post subject: Reply with quote

Okay, it's done. Smile

Laid the Kronos on it's front onto two folded blankets, joysticks protected with spools of isolating tape around them (still a bit scared about the knobs), removed roughly 10.000 screws from the bottom panel, opened it up, loosened the glue under the shields (metal and plastic) using a thin guitar pick, disconnected two connectors at the side of the keybed too fast, lifted out the keybed and failed with doing so. Just couldn't get that thing out.

Thus I removed the aluminum front bar after getting the headphones socket out of the way (two silver crews holding it), fixed with just two solid silver screws with spring washers. Now I was able to lift out the keybed, put it on the table.

Nothing unusual to see. So I took out the D4 key, using the trusty guitar pick for releasing the stop tab at the left side. Nothing damaged, damn!
Thus I also removed D1 for comparison. Just identical. But wait ... The flat spring looked different; absolutely straight with the D1 key, but slightly bent with the D4 key, at two places, like an "S". Plus, there was some white plastic debris at the place where the D4 key holds the spring.

So D1 and D4 components changed places. And the noise was gone at D4, shifted to D1. It's far better at D1, not that obvious - plus, D1 is - surprise - a key I rarely use.

Reassembled the thing, had severe problems inserting the keybed - it just seemed to be too long, now. Huh? "Secret": Needs to get "hinged" at the right side near the connectors first.

Large connector wasn't willing to fit. Got a loupe, inspected the pins. Two of them slightly bent by pulling out the connector too fast and at an angle. Corrected the pins, connector now slipped in fine.

Fixed the shields, glue was still sticky enough, put the bottom plate back on.

First tightened the two silver screws on the bottom slightly, put in one regular case screw and one (larger) screw for fixing the keybed, checked the holes in the bottom plate, rearranged the plate so all screw holes were in the center of the openings, then tightened the screws, continued with the remaining ones.
Checked the gap between keybed and front bar with a credit card, all fine and evenly.
Booted the Kronos, seems all well. Smile

I'll now ask the dealer to send me a new D key plus spring - and if I ever feel disturbed by the D1 noise, I'll just repeat the procedure.
Problem solved.

At least that's what I hope. Very Happy
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KK
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Joined: 13 Oct 2016
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PostPosted: Fri Apr 24, 2020 12:27 am    Post subject: Reply with quote

Congrats Klosterbruder to have successfully fixed a key on your RH3 action. I opened my Kronos quite a few times already and reading your last post you indeed figured out how to do it just fine, which is certainly not easy. Cool
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average_male



Joined: 07 Feb 2011
Posts: 46

PostPosted: Fri Apr 24, 2020 11:24 pm    Post subject: Reply with quote

Nice going Klosterbruder. There isn’t much to the keys, Mechanically; just a stationary contact strip, key spring and the actual key. When I serviced a Kronos, replacing of the spring can sometimes hang and not seat correctly.

I really like your dad’s philosophy regarding buying the best quality for the things that bring you the most happiness. The trick is knowing what will make you happy; I feel that my Kronos fits this criteria pretty well, sounds great and has tons of features to keep me tinkering for many days on end. Very happy with it.
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Bobcat22
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Joined: 12 Nov 2018
Posts: 72

PostPosted: Mon May 25, 2020 4:45 pm    Post subject: What you have described is a Korg design problem. Reply with quote

The plastic shards are caused by the return spring. A bad Korg design. One end of the return spring (V-shape, which is sharp as a blade) digs into the plastic key's spring receiver. More advanced stages, the key starts to drop as more of the plastic is cut away by the spring. The key drops because the spring receiver gets cut away, lengthening the distance of the spring mount.

The solution: Gain access to the keybed and retrofit the spring end with a cap bonded by a "Crazy Glue" like material. After owning other instruments, I have come to the conclusion that Roland and Yamaha have generally better builds. Not to mention some others companies.
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GregC
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Joined: 15 May 2002
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PostPosted: Mon May 25, 2020 7:59 pm    Post subject: Reply with quote

thats interesting

I thought that having an " upside down PC" mounted by support screws inside the chassis was a questionable design
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KK
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Joined: 13 Oct 2016
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PostPosted: Mon May 25, 2020 11:40 pm    Post subject: Re: What you have described is a Korg design problem. Reply with quote

Bobcat22 wrote:
The plastic shards are caused by the return spring. A bad Korg design. One end of the return spring (V-shape, which is sharp as a blade) digs into the plastic key's spring receiver. More advanced stages, the key starts to drop as more of the plastic is cut away by the spring. The key drops because the spring receiver gets cut away, lengthening the distance of the spring mount.

The solution: Gain access to the keybed and retrofit the spring end with a cap bonded by a "Crazy Glue" like material. After owning other instruments, I have come to the conclusion that Roland and Yamaha have generally better builds. Not to mention some others companies.

The problem you mention affect only a number of Kronos LS models. For all "conventional" Kronos-2 with weighted RH3 actions, the V-shaped side of the springs are against the keys metal which is near indestructible.

I have repaired many electronic keyboards over the years and I consider the standard weighted RH3 action to be very solid and of better quality compared to other ones/brands, especially Fatar.
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Kronos : Custom velocity curves12345Kronos : Aftertouch hardware solution
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GregC
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Joined: 15 May 2002
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Location: Discovery Bay (San Francisco Bay Area)

PostPosted: Mon May 25, 2020 11:43 pm    Post subject: Re: What you have described is a Korg design problem. Reply with quote

KK wrote:
Bobcat22 wrote:
The plastic shards are caused by the return spring. A bad Korg design. One end of the return spring (V-shape, which is sharp as a blade) digs into the plastic key's spring receiver. More advanced stages, the key starts to drop as more of the plastic is cut away by the spring. The key drops because the spring receiver gets cut away, lengthening the distance of the spring mount.

The solution: Gain access to the keybed and retrofit the spring end with a cap bonded by a "Crazy Glue" like material. After owning other instruments, I have come to the conclusion that Roland and Yamaha have generally better builds. Not to mention some others companies.

The problem you mention affect only a number of Kronos LS models. For all "conventional" Kronos-2 with weighted RH3 actions, the V-shaped side of the springs are against the keys metal which is near indestructible.

I have repaired and modified many electronic keyboards over the decades and I consider the weighted RH3 action to be very solid and of much better quality compared to other ones, including Fatar.


thank you for quantifying the issue was the LS model.

My 9 yr old Kronos 88 has been perfect.
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KK
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PostPosted: Mon May 25, 2020 11:51 pm    Post subject: Re: What you have described is a Korg design problem. Reply with quote

GregC wrote:
thank you for quantifying the issue was the LS model.

My 9 yr old Kronos 88 has been perfect.

Same here, my Kronos 2 is only 4 years old but with lots of classical piano played on it almost daily I can assure anyone that the RH3 is very reliable. As a comparison, the Fatar action on my Kurzweil PC2X was falling apart after 2 years with similar practice.
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Bobcat22
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Joined: 12 Nov 2018
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PostPosted: Tue May 26, 2020 5:38 pm    Post subject: Another Botched Job is the Keybed on the 61/76 Versions Reply with quote

The pivot or fulcrum on the keys are not standard and restricts the position of the hand while playing. On the cheapest Casios, Yamahas and Rolands, this does not exist. So that rules out the 61/76 models.
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GregC
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PostPosted: Tue May 26, 2020 5:44 pm    Post subject: Re: Another Botched Job is the Keybed on the 61/76 Versions Reply with quote

Bobcat22 wrote:
The pivot or fulcrum on the keys are not standard and restricts the position of the hand while playing. On the cheapest Casios, Yamahas and Rolands, this does not exist. So that rules out the 61/76 models.


seems like you have experience on an important topic.

Do you have an opinion and analysis of the MODX88 key bed ?
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