Kawai PN80 E-Piano Reparatur

Repair: Kawai PN 80 E-Piano

Lesedauer: 

ungefähr 4:19 Minuten

Since there is no service manual available on the internet by the time of writing this blog post I thought it might be a good idea to sum up some recommendations. This writeup is about a PN 80 but applies to all pianos of the PN series (like PN 60, PN 70, PN 81, PN 90 and PN 100), since they use the same hardware, basically.

The PN 80 is a 24-note polyphonic piano designed by Kawai in the early 1990ies. In Germany it cost about 3500 DM (~ 1800 €) at the time. It features eight 16-Bit Sounds (2 Piano, 2 E-Piano, Vibes, Harpsichord, Strings, Organ) and has 88 weighted keys. It's not as heavy as comparable e-pianos of that size. It's body is built of less wood and more light metal and it features weighted keys instead of hammer action, that's why.

The sound is a bit cheap in 2018, compared to modern E-Pianos with lots of memory. Memory was expensive back then and Kawai did their best to find a good compromise. But it still sounds a lot better than the sound of cheap newer pianos like the Hemingway DP series.

"Cheap" regarding the PN 80 means from a today point of view, the sustain sample loop starts a bit early and the piano lacks an equalizer to lower the typical japanese sound brilliance. Inside there are only two speakers (loud enough, though) compared to the four and more used today.

The overall manufacturing is very well made and robust. Tidy wiring, separate metal box for the mainboard and controls. Plus not much dust inside despite of me being the first one ever opening it. That's why you can still use it after more than 20 years of intensive playing. Well played, Kawai.

Still, this PN 80 had two major problems.

  • no sound at all
  • ⅔ of the key weights had fallen off the keys

Opening the piano

Do NOT start opening the piano on the rear. The six screws on the backside hold hinges.

Instead, start with 6 screws (bottom side) holding the front metal sheet covering the keys on the front side but DO NOT lift the sheet before having read the next sentences. Hold it safely while removing the screws and KEEP holding it. Note! There are 4 metal screws and two wood screws in the order M-W-M-M-W-M. Lift the metal sheet carefully since the power LED is attached to it on the left side. Get rid of its screw and finally put the sheet aside.

Now screw off 4 screws close to the edge on the left and right bottom. Lift up the piano top like a foldable cover. Remove the ground leads if you need to enlarge the opening angle, e.g. to reach the mainboard in the metal box inside.

Fixing the issues

Oh so quiet

The no-sound-issue was solved quickly. After the usual cleaning plus button and fader maintenance (I use Kontakt Chemie Tuner 600 spray for potentiometer issues) there was sound on one stereo side. It turned out to be a torn volume fader. I got a replacement fader from synth-parts.com. The offered Korg 30 mm fader has the same size and specification.

Weights

The PN 80 has quite heavy weights (21 g) in each plastic key to imitate a real piano feeling. Kawai did glue them below the tip of a key. Unfortunately, the glue used here fails after some years of usage so you have to find a sustaining solution.

I've come up with two ideas and I used hot glue for both.

Take the weight (I warmed it before in the sun light), put some hot glue on the bottom and press it back into the designated space in the key. Do that fast since hot glue tends to cool fast when in contact with metal (thats why I warmed it in the sun). While pressing it deep into the key hold the key on the upperside (now bottom side because of upside down; to prevent breaking it) and use some tool to push the metal block down. The back of pliers e.g. will do.

Now

  • either scratch some scratches into the key hole (haha) above the block with some sharp knife and put some more hot glue into the whole on the left and right side. The scratches will hopefully make the glue stick better to the plastic.
  • or take a short peace of straight spring steel, slightly longer than the diagonal width of the key hole. Press that metal piece in the whole and fix it with hot glue.
Kawai PN80 E-Piano Weight Repair

You need to do some cleaning afterwards and cut away all hot glue strings between the keys. For the piano I serviced in May 2018 I used the first of these two methods. I'll report back if this does not work in the long run.

 

Comments/ Kommentare

#01

Hi , yesterday i bought the used Kawai PN 70 from my friend it was working great at my friend place before i bought it , when i try to connect the Kawai PN 70 through power cord and try to swith on the piano the power is not passing to piano it doesn't on.

please can you help me what would be the problem why the power is not passing to the keboard?

Thanks
Kumar

Hi Kumar,
hard to tell from here what the problem might be. What happened once you connected it and switched on? Did the LED light up for a short time? Did it smell? Did you hear something that could indicate a problem? Did something happen during the transport? Did it fall down? Did you transport it on a pretty uneven road?

It could simply be the power adapter. Check the voltage and polarity with a meter. Also check if the connection is solid. If the adapter fails, get a new one with the exact same parameters regarding voltage, +/- polarity and power in mA. The mA value may be higher but not lower.

If it's not the adapter, disconnect the piano, open it up. I do not know exactly what the PN 70 looks like from the inside, but I guess you might have to open a metal box to find the main board.

It could be a blown fuse, though I don't think there are fuses because it's adapter driven. If a fuse is blown, this might have been a problem from outside (wrong voltage) or a short on the amp board. Change the fuse(s) and see what happens. Only use the recommended type of fuse(s), it's usually written on the board or the fuse holder. If you use the wrong type severe damage can happen to components that are still working.

If the fuses are ok (if there are any) check if all wiring is still in the right place (transport vibrations?). Look if something looks burnt. Look first at the amplifier IC that usually is attached to a large heat sink. It could also be a voltage regulator, also attached to a heat sink. A lot more could have gone wrong, so one should check this with proper equipment, starting by checking the voltages inside.

If the LED still lights up and you just don't hear anything, connect the piano to a MIDI device to check if the keyboard is working. If so, check if MIDI is set to LOCAL OFF. Look in the Owner's Manual to set MIDI to LOCAL ON. Alternatively check with proper equipment (oscilloscope) if there is output from the D/A converter. To find it, check the types of ICs (look for a rather small one) and do a search "datasheet XYZ123456". Then trace the signal and see which component blocks it.

Hope this helps. Good luck!
Ulf

Adapter for Kawai is special. Where other have + pole Kawai have - pole.

If you can't get an adapter with correct polarity you'll have to resolder the connector by cutting the wire and switching the poles. I know that switchable adapters are no choice in this case because there is not enough space around the jack on the piano, which is a pity.

Add new comment/ Neuen Kommentar schreiben

Weiteres
[Boah!
Haben Sie
einen großen
Bildschirm]