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Piano World forum member "Jdiggity1" was recently schooled in multiculturalism via a run-in with the wildly different wall voltage "standards" (i.e. hazardous legacy) used in various countries. He was lured into this rocky scenario, nay entrapped, by another charming divergence of said countries, that insidious and overly complex melange of market protection mechanisms and taxation schemes found at the various borders, which tends to jack import retail prices sky high. The full tale of woe is recounted here.

Jdiggity's pain is our gain, however - he took many high quality photos of his Kawai MP10 in the buff after the electrician got it naked (but then had to go home to get his soldering iron, likely story) and posted them at Imageshack so we could all leer and drool together. Let's take a lascivious look!


Here is the top of the case flipped over to show the innards. That's the trouble maker (power supply) on the left, the pitch & mod wheels on the right, the front panel display / control printed wiring boards (PWBs) at center, the "brain board" PWB above them at center, and some misc. PWBs at the upper right.


The power supply - the big chunk of iron at the fore clearly indicates that this is an older linear design. Upper center is where the IEC power (mains) jack would normally be if it didn't flame out, to the right of that is the power switch, both of which are connected to a fuse and capacitor board on the right. AC then flows to the boat anchor (power transformer), the low voltage windings of which are routed to the board at upper left where rectification, filtering, and regulation occur. Note the big fat gray cable that terminates on the small PWB to the right, this is for the front panel USB thumb drive.

Anyway, say what you will about "wall warts" but the modern switching variety are a lot lighter and more efficient than these older designs, and they normally can handle any voltage found leaking from wall outlets the world 'round.


A close-up of the fuse and capacitor board. The usual way to handle multiple insane world voltages here is to play series / parallel games with the power transformer primary windings (bottom connector) along with resizing the fuse amperage rating.

Jdiggity adds: "The three vertical lines to the lower right of the board are the voltage selector things, the middle line is the 120V 'option'. The electrician configured the board to process 240V with a simple solder job involving the far-right line there."


The linear regulator board. The large upright chip located at the bottom (behind the big electrolytic cap) is the full wave rectifier. The three regulator chips have no heatsinks, which is interesting. I wonder what that big rectifier and choke are up to?


The pitch & mod wheels seem to be using the pot shafts as their main bearings (not the best, but par for the course). The PWBs at center have I/O jacks and stuff on them, and there is a large analog board located above.


The large analog board. Many dual op-amps (NE5532N, 45800), several 8-to-1 analog switches (74HC4051), and some random transistors and caps. The center left connector has three stereo audio co-ax wires connected to it - these lead to the volume and line-in faders on the front panel. And there is a strangely empty connector at the upper right. From the high jumper count this looks like a single layer PWB.


There certainly are a lot of wiring harnesses in here! The left blue one goes to the LCD display board. There is another small I/O board located beneath the brain board.


Mmmm, brains! I see three large proprietary (house marked) QFPs. The two marked "Kawai K022-FP" appear in the MP6, as does the one marked "72030W200FP" (this may be marked "72030K200FP" on the MP6?). The two TSOP II chips marked "M12L2561616A" are 4M x 16 Bit x 4 Banks Synchronous DRAM, and these also reside on the MP6 brain board. In fact, if you look at the MP6 brain board, it seems to be identical to this, with a few minor component population differences. Finally, and apropos of nothing I suppose, a total of 12 screws are employed to hold this smallish board down - that's some serious fastening power!

To be continued... (PW only allows 8 pix/post)

Continued from previous post:


The key assembly. Note the slot formed between the center E & F keys, and the green wiring harness.


A close-up of the keys, which are individually numbered. I like the way Kawai locates the pivot point farther back for the black keys like real pianos do, which helps to even out the mechanical advantage. The keys appear to be solid wood, with pins and felt lined slots for the pivots. I assume the resting heights can be adjusted via paper washers under the keys at the pins?


Side view of the key mechanism, with tape measure to show key pivot locations.


The highest key depressed. Let-off feel is provided by a piece of rubber that a prong on the hammer must brush past. The hammer impact cushion is really thick.


Close-up of the mechanism. The hammers are plastic with steel weights riveted to the ends. Each hammer has an adjustable jack in contact with the back of the key. An inclined PWB holds the ubiquitous rubber switches which are activated by the hammers. The rubber & prong let-off mechanism is clearer here. Note the highly complex one-piece aluminum extrusion holding everything together - it even forms the hinge for the hammers!

Hats off to Jdiggity for these most excellent nekid pichures!

Look at that action! That is exactly why the RM3 is the so impressive. It looks much like a shrunken down acoustic piano action. Thanks for sharing!

That action is indeed impressive looks like a real Kawai piano actually.

Canon EOS 60D - nice camera!

I see what you did there!
It's a ripper of a camera.

For those not versed in Aussie:

http://www.word-detective.com/2011/01/28/ripper/

(I'm British, but was raised on a diet of Australian TV soaps, and therefore speak fluent Aussie.)

Dewster, not a good idea to use a switching regulator in an audio device like this.

I can tell there will be more lessons to come!

Hmm. I disagree. The switching frequency is usually way outside human hearing. You could have clocks alias down into the audio, but that's always something to consider in a digital audio device.

Not always (10Khz in some cases).

Anyways the power quality is way lesser, the web is full of examples, and you know, every hi-fi amplifier uses a linear power supply for a reason. Quick link:

http://www.amb.org/forum/thomass-beta24-build-t1178-20.html#p12536

Of course, without knowing the PSRR of the Kawai circuitry speaking about the power is useless. Other problem with SMPS is the electromagnetic field they generate, etc...

I for one, much prefer a linear power supply for professional audio, unless I have to use different voltages.

Nice thread thanks to Dewster and Jdiggity.

Great photos, thanks so much for posting!


For appliances with lots of exposed analogue circuitry, such as a mixer, I too would consider using a linear power supply. But for a DP, which does all processing in the digital domain and then converts to analogue at the output jack, switch mode supplies are perfectly okay. The analogue circuits in a DP consume so little current it's quite easy to filter the supply lines using passive components (unlike a mixer or power amp).

Great photos! Thanks for posting.

I KNEW IT!!!!

Well, stone the flamin' crows!

Rack off you dag...me too...teenage years spent marvelling at Neighbours and the like. I'm sure it was the Aussies that first thought it might be a good idea to paint walls brown. All the sets had brown walls, especially Sons and Daughters.

So is this similar to the action inside an ES6?

Do you think there would be enough room to put a Nord Piano sound engine (bain) board inside this? May be it is possible to have a two character piano in one case.

Thanks for sharing