Hohner Pianet C – under the covers

The foolish part of me wants to believe there’s something romantic about 50 years of dust and dirt. Collected across time and space, layers of history waiting to reveal hidden secrets, like some daring archaeological dig …

dust part 1

In reality, it’s just dust and dirt. And the occasional silverfish.

more pianet dust

As keyboards go, the Hohner Pianet C is ridiculously easy to disassemble.

Each key is held in place by a simple t-bar on a spring. Push down, quarter turn (counter-clockwise), and the key pops up, propelled by the spring that acts as the rocker mechanism.

Each white key has a lip that locks in under the frame. To get this into place when you’re re-assembling the keyboard, you have to slide the key forward to position the rocker spring, then tuck the lip back under the frame, and finally lock down the t-bar. Because of the layout of the keys, this makes it important to disassemble them from right to left, and reassemble them in the opposite direction. You’ll learn this after you remove the key on the far left first, and then realise you can’t put it back in. As I did.

So this is what the inside of the Hohner Pianet C looks like once the keys have been removed (click for larger image):

Hohner Pianet C without keys

You can see the earth wire (below the top blue felt) that is meant to ground the keys has become disconnected from the frame on the left. Thanks to modern advances in copper tape I’ll be replacing that wire with some high-fidelity snail and slug barrier.

The felts themselves (two blue and one red) are in really good condition, but have become compressed over the years. I’ll probably keep the bottom two felts, but replace the one under the grounding wire so it makes better contact with keys.

Curiously, the centre rail where the t-bars connect is wired to ground (on one end at least), even though the t-bars don’t appear to have any other connection to close a circuit.

To the right of centre are the relay switch and electronics for the volume control

Hohner Pianet C volume bar electronics

and at the back right is the pre-amp and transformer.

It’s great to have easy access to the electronics. Fixing them is the next step.

One capacitor at a time.




  1. I actually think I may have two spare of those potentiometers if you ever need them. I got them with some salvaged paint parts years ago, but I don’t have pots like that in a Pianet N.

    1. Thanks for the offer. I got about 80% of the way through replacing the electronics before the project got delayed by …. life. Your comment is a good incentive for me to get back into it!

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