On Wednesday I have a guy from a Yamaha certified repair center coming over to fix a little issue with a black key. It makes a woody noise when released, probably some damping material missing.

I will try to get some fotos of the inside. I'm posting this now to ask if anyone wants me to do additional stuff, maybe measure the key length or something?

Edit: Alright, here are all the images I could take.

As for measurements, since he ended up not needing to remove the whole action (merely changing the angle of one of those screws between the keys in the front fixed the noisy release sound of that one black key) I could only measure little, and not very accurately. Basically holing the tape measure in the air.

The length of the key, the whole thing from front to back, seems to be about 480 mm (about 18.9 inches), key depth measured at the front of white key was 26 mm (little more than an inch). Hope that helps a bit.

It wasn't too bad exposing the action. Basically unscrew the top row of screws on the back, then you can remove the top cover with the speakers (there is one cable to be unplugged first, seen in image 7). Then you have to remove the black thing in the middle as in image 12 and 13. Then remove the lid in the front which can be lifted out easily.

We talked about how much more work it would be to completely remove the action and we didn't think it'd be much more effort. In the last image there is one of the screws that would probably need to be loosened, and a couple more around the middle of the action which would need a long screw driver. Most likely the whole action could then be slided out.

He had a service manual describing everything. Asked him to email it to me, but sadly he's not allowed to do that.

The "guide pin" he offered to lube to lighten the action are those visible in picture 16 to 19 with the red felt material around them. After examining them we both concluded that it would probably not help much since there is very little friction there to begin with.

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4 (sensors)


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[img]http://i44.tinypic.com/35mjzx0.jpg[/img]

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[img]http://i40.tinypic.com/add8pw.jpg[/img]

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[img]http://i44.tinypic.com/v6q2xz.jpg[/img]

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[img]http://i44.tinypic.com/2edtxzl.jpg[/img]

Yes as a fellow N1 owner and looking to get my action regulated, I would love to see photos, measure the key depth, etc. may I ask how you or the technician is getting to the action? I hear the N1s are tricky to get to the action.

If you can take a good picture of the under-key sensors and the hammer sensors, that would be great.

There's a lot of talk and uncertainty about this dual sensor system: (1) whether the hammer sensors are optical or they the rubber type that most DP's have (2) which set of sensors does velocity and which does damper, etc.

Since people have been talking about regulation, if you could take pictures of as much as the regulatable parts of the action too, that would be great. Basically it would be nice to know things like if you changed the keyboard weight, would it affect the velocity calculation somehow.

Measuring key length is also great, though we have a good idea of what is probably is.

I'm looking forward to whatever photos you are able to get!

I second the key length (pivot to played end of a white key). Yamaha implied it was the same as that of a large grand action, but others have said it is shorter, so it would be nice to be able to resolve this.

I second the key switch as well, wondering mainly if it is optical or rubber.

Pics of the main brain board might be useful too.

I have no idea, I will try to watch how he opens the thing. He is n't a piano technician, just a general service guy for Yamaha and other brands. I chose him from a list on the Yamaha site that they pointed me to after I wrote to their support.

I asked him if he would be able to lighten the touch, but as expected I would need a proper piano technician who would probably spend a whole afternoon changing the weight on each key.

He did talk to Yamaha about it apparently. They said he could try to lube some kind of "guide pin" or something? I can't properly translate it, nor do I know what exactly they meant by it. I know precious little about piano actions. He offered to do it for CHF 150 (about $160 at current rates), but I really doubt it will help much.

Updated the original post. Last 4 images don't show up for some reason, but you can click the links.

Great job on the pics! Thank you for sharing. I'm going to just play my N1 for a while longer and see if it loosens up some. If not, no big deal. I would guess taking the N1 apart must have been a task with the speakers and wiring, etc. what did you have done to your N1? Did the guy do anything to your action? Is it back together? Does it play any differently? Sorry for all the questions just a very curious fellow N1 owner. Thanks again Gigantoad.

Sorry I got ahead of myself, did he do anything else to your action other than the fix to your key? Also how long have you had your N1?

Thanks!

Too bad you didn't measure the key length to the key pivot post, that's the most important in terms of mechanical advantage as perceived by the player. Overall length doesn't mean too much.

Comparing #5 to #11 there seems to be a huge difference in hammer weight grading from bass to treble. Those bass weights look particularly massive, I can imagine why people say the AG has a heavy feel.

The brain board pics unfortunately don't have enough resolution to read any of the IC numbers.

Those look like individual amplifier boards in #2.

#4 is very interesting, the optical sensors on the hammers use fiber optics, not something I would have expected. It looks like the fibers are terminated at that block in #13. And I wonder if this is just a single sensor on the hammer? Perhaps they have a sensor on the key and then use the time difference between them instead of a third sensor?

Where are the speakers in #7, #8, and #9 located? They look rather small, perhaps 5" diameter max?

I assume those round wooden things in #16 - #18 are the letoff buttons.

I'll add this to the "DPs Exposed!" thread - thanks again!

I have edited the text of the original post as well to describe the procedure as best as I could. It wasn't too bad really

He fixed an issue with a black key that made a louder noise than the other keys when releasing it. Turned out it hit one of those screws between the keys (best visible in image 19). By adjusting that screw a little the key now moves freely again.

There is definitely an optical key sensor...if it's very dark in the room you can see a gentle red light emanating from between the keys, which I assume is something to do with the sensors. Seeing these very welcome pictures from Gigantoad seems to answer the question about whether the hammer sensors are optical or rubber buttons.

Yeah, I think we've always known the key sensors are optical, but the hammer sensors we didn't know about.

So can you guys explain how you know the hammer sensors are optical? It seems like the sensor is out of sight. Or are those yellow tabs attached to the hammer shanks in #4 a way of breaking a beam of light? And then the light goes down the optical fibers and is actually sensed in some location all together. Is that right?

Are we still thinking that hammer sensors calculate the velocity while key sensors govern the damper? I only see one fiber coming out of each key (and one going in) which makes me wonder if the hammer sensors govern the dampers (you would need two paths to be broken in order to calculate velocity).

It seems those tabs on the hammers move up through those slits and the yellow thingies on top somehow measure that movement in some optical way. I don't think there is anything more hidden underneath.

On the GranTouch, the first generation hybrid from Yamaha, there is a metal tab under every key that breaks the optical beam when the key is depressed.

I'm sure the N series is the same.

Well, they are connected with fibre optic cabling - this is not my area but I assume they are therefore optical sensors?

Thanks Gigantoad, very interesting pictures indeed!



I measured the length of the keys on my C3 and they are also 480mm long (more or less). So it's possible that this action has the same geometry as the C3's.
It's interesting that the repetition levers are not made of wood (photo #4 and #11, the white levers between the hammer shanks) - looks like nylon or something similar.



Dewster, I remember seeing the action of a silent grand from Yamaha. There is a hole in the shutter.
If I remember correctly, when you press the key at one point, as the shank goes up, the light is interrupted. At the end of the stroke the light passes through the hole again. So the time the sensor goes dark is proportional to the speed of the hammer, similar to two sensor.
I think the sensor under the key, besides "lifting" the dampers, allows the system to know when the light interruption is from the hammer coming down, so that no note is triggered.

That doesn't seem entirely foolproof. What if you play a note light enough for the edge of shutter to just barely obscure the beam before falling back - couldn't that cause a false trigger?

If they have some trick in software to somehow guard against this, might that sometimes quash a valid trigger?

The way to do this unambiguously (i.e. correctly) is to have two sensors, not two events with a single sensor.

That's a good point.
Then maybe it's the key that triggers the note, and the hammer sensor is used only to compute the speed? Or a combination of both?
In the case you describe, the key would be up and no note would be triggered.

Here is an image of the shutter of a C3S:


The oval shape of the hole seems to account for hammer checking, as the hammer goes down a little bit after hitting the string.
In any case, it would be interesting to know exactly why (and how) they use two set of sensors, while it seem to be possible to make the whole thing work with sensors under the key only (e.g. PNOscan).

This is what Yamaha says in the specs for the C3S:

Hammer Sensors
88 one-beam, two-point optical fiber sensors
Key Sensors
88 two-beam, four-point optical fiber sensors (key-release velocity sensing)

The 'key release velocity sensing' bit makes things even more interesting....

I believe on my GranTouch there were two sets of optical sensors, one to measure the velocity of the hammer and the other to register key on\key off - the piece of metal embedded into the bottom of the key which interrupted the light.

There were also, of course, sensors for the three pedals.

I'm fairly certain this is a mature technology.

Though PNOscan is a flawed technology in that you can tap the key fast so that the hammer flies up and hits the string, but if you don't press the key all the way down, it doesn't register as a strike. Measuring velocity on the hammer seems like it would be sufficient (this is how most DP's work) but I can't think of how under-key sensors alone can do a sufficient job.

I wonder why the C3S has two sensors (four beams) under the keys. Isn't one two-beam sensor enough to measure velocity? I guess I don't understand how they are distributing the work here.

I'll be honest, I don't really care much for the tech specs of my N1. It plays as fast as I want, it doesn't drop notes, and offers the best playing and practicing experience I've had on a non acoustic grand. I'd have to say without a doubt, because of the N1, and the ability to spend my time practicing on its acoustic action, my technique has progressed leaps and bounds. And there's no transition going to and fro acoustic pianos like there always used to be.

Thanks for that picture Erard!


As long as the key and hammer sensors are somehow physically calibrated together. However, there's a fair amount of slop in a key/hammer mechanism which might limit the precision of this calibration or make it difficult to carry out. No one likes to manufacture products that need excessive tweaking on the assembly line.


When they say "two-point" for a single sensor I believe they are describing the way a detected beam at the hammer can either mean the hammer is down or up but not within a certain region in between, the transitions in and out of the region marking two distinct positions/times. Doing this with two beams at the key gives what they call "four-point". Not sure what Yamaha is doing under the key, but with two beams you could easily do a Gray Code on the position and know for certain which of four quadrants it currently resides in, and the transitions would give you three distinct position/time detections.

If they are using the key-up velocity then I can see why they have two sensors on each key. And they probably convinced themselves that this, combined with a single sensor on the hammer with two positions, was sufficient to differentiate the various hammer/key scenarios. My feeling is that it is a bit too tricky.


It could still have quirks and bugs, particularly if there is software involved.

Has anyone here experienced an AG misfiring (note not playing when it should, note velocity obviously incorrect, etc.)?

Thankfully no. It has never done anything untoward at all. Neither did the GranTouch I owned for a few years previously. I think Dave is right, the technology is both mature and in my experience extremely reliable.

Cheers,

Steve

I haven't experienced droppped notes like what has been widely documented with the RD700GXF/RD700NX but I have played a note that didn't sound. It's very very rare, but it has happened. The AGs aren't bug proof and they aren't perfect, but they're the closest thing to playing a quality acoustic grand piano you can get out of the non acoustic world. I am very happy with mine.

I've had a few notes that I expected to hear and they didn't sound. To be fair, I've had the same happen on an acoustic so I assume the problem was me.

Interesting. Not saying that's necessarily what's going on, but killing a note rather than playing it due an ambiguous hammer sensor scenario is what I would probably do faced with the AG sensor configuration. But if I designed it I think I'd put a second real sensor on each hammer. And if money was no object I'd put continuous positional sensors on the hammers and keys.

Dewster, I'm confident with your expertise, you'd most certainly come up with oe real monster of a DP. The only problem, is none of us coud afford it!

That's my experience too. It's easy to conclude it's performer error, but I have experienced instances with the N2 where I was surprised the note didn't sound. I haven't gone back and tried to repeat the issue.

I just completely dismantled my (brand new) N1 because one of the keys regularly got stuck. (The problem was that the felt in the middle hole of the key in question was sticking out a little, preventing the key from moving smoothly.)

There was the question above as to how the position of the keys is tracked: There are two light barriers for each key, one easily visible on top of the keys in this bridge running across, and the other below the keys where you press them. From the way it's built, it's not clear to me why two sensors are needed.

There was also the question above as to how to take the N1 apart. It's fairly simple: Loosen the four screws along the upper edge of the back wall and you can slide the lid forward, disconnect the speaker cable and then lift the lid off. Everything else is just as simple and mostly self-explanatory. The only tricky thing for me was when reassembling the whole thing, I had trouble with the two long screws that adjust the heigth of this slat right above the keyboard in the front. You've got to leave the screws in there and just remove the (funny looking and ackwardly shaped) nuts - or you might end up ruining the screws as I did.)

And you've just voided your warranty. Why would you do this yourself instead of calling the dealer you bought it from, or Yamaha? Crazy....

He did not void his warranty.

When I had work done on my GranTouch, I opened the piano for the tech and showed him what I had done which was to stuff foam to prevent rattles and apply tape and\or plastic ties to keep wires and cable from vibrating against something.

I've made minor changes to my N3 ... and posted those improvements here and to Yamaha. There was no talk of voiding my warranty.