Over the years you accumulate stuff. Some good stuff, some bad stuff, and some stuff that just doesn’t make sense at the time. The good news is that, sometimes that stuff ends up making some sort of sense. With enough time and the right conditions, things that might have been confusing can suddenly become clear, and lead you down a path you hadn’t considered travelling.
And so it is, 20 or so years since my Dad tried to get me interested in electronics, I’ve finally discovered a reason to delve back into that world and expand on my basic knowledge by restoring, renovating and upgrading the electronics (and other parts) of classic keyboards.
The (first) instrument
The first instrument I was going to tackle is my sadly neglected Rhodes 73 Mark II Stage Piano. As luck would have it, just as I started to organise the parts and equipment I’d need to begin work, the opportunity came up to acquire an instrument I’d never really been aware of before – the Hohner Pianet C.
Unlike the Rhodes, which generates sound when the hammer of a key hits a tine, the Pianet generates sound by ‘plucking’ a metal reed. Each key is a simple rocker mechanism with a sticky pad attached to the end, which pulls the reed up when the key is pressed. Eventually the stickiness of the pad is not enough to hold the reed and it releases, vibrating at the appropriate frequency for the given key. This generates a unique tone that is darker than the more common Rhodes or Wurlitzer.
According to Wikipedia, the Hohner Pianet C is the second of the pianet models manufactured by the Hohner company, somewhere between 1963 and 1966. Considering the age of this instrument, it’s in pretty good condition and is a testament to how well things were made at Hohner.
The case
Cosmetically, the case is made of particle board with a timber veneer, which has generally held up well apart from the normal scuffs and scratches you’d expect after 50 years. The only exception is the left-hand side, where the veneer has been badly damaged and is separating from the particle board. This will have to be replaced, once I identify the type of timber the veneer is meant to be.
The particle board underneath is not veneered and is starting to shed. This will have to be sealed to prevent it deteriorating further. One side of the lid rest is missing, and both screws from the middle panel are gone. The screws should be easy to replace, but the piece of timber for the lid rest will be a challenge.
According to Wikipedia, the model C had a key lock in the middle of the lid, but this one has no sign of a lock ever being installed. I guess they could have made variations for different markets and/or price points. Wikipedia also states that this unit came with four matching legs. These are no longer with the instrument, and it looks like the original mounts have been replaced with alternative mounts, for alternative, missing legs.
This model has a Vibrato switch on the right-hand side of the keyboard and a bar under the base, operated by your knee, which acts as a volume control.
Apparently someone thought that would be a good idea.
The sound
In order to make a “here’s what it sounded like before restoration” recording, there has to be …. sound. Unfortunately, in its present state the pianet has 60 keys that generate the sounds of silence. The one key that does make a tone is so quiet against the ground loop and background noise that it can accurately be described as the key of HUMMMMNBBBBRRSSSSSST. So no recording.
The sound I’m hoping to achieve can be heard in this demo video from Ken Rich Sound Services:
The unit in the video is a model N, which came after the C, but the sound of this unit should be roughly the same.
I’m actually pretty surprised that the electronics are still working at all, given the age. Power goes through the unit, and the lamp in the circuit glows impressively – especially when the Vibrato is activated.
I suspect the two main fixes will be replacing all of the pads on the keys, and the capacitors in the circuit. Time will tell.
Next step
So that’s the current state of this instrument. The next steps will be to disassemble the entire unit for cleaning, inspect the pads, and test the electronics.
One note at a time.
24track.net 
hey man. Glad to have landed on your page I have an old Pianet N that I got working years back but am constantly looking to update. Seems like the C and the N look a lot alike inside. Some helpful information here. I too am planning to document my restoration on my site. http://hohnerpianet.wordpress.com
Nice Pianet C mate!
Just a kind word of warning, be careful poking around inside an old Pianet, there’s around 400 volts on that pickup next to the reeds and many other places with very bitey voltages.
I just got myself a ’64 Pianet N and it didn’t take much to get it back to working condition. These Hohners are surprisingly hardy, apart from the sticky hammers which all fall to pieces over time.
First, take all of the old pads off. The rubber part will have separated from the leather pad and all of the foam will have turned to sticky goo.
With the Pianet NOT plugged into mains power, clean the reeds with a Q tip (cotton bud), being careful not to leave any fluff behind. If some of the goo or oil from the pads is stubborn, use a little isopropyl alcohol on the Q tip, being careful not to get any on the pickup (if you do, don’t plug the Pianet in for at least an hour)
Once you’ve done this you can test if the output still works, just tap a reed gently with an insulated item (something hard and plastic preferably) and see if it makes a musical sound.
If it makes a sound, you’re most likely going to have a working Pianet on your hands, so buy a set of new hammers from Ken Rich Sound Services (http://kenrichsounds.com/) I have a set of these and they are great. Expensive, but worth it.
Don’t worry too much about hum and crackle if you’re listening to the output with the lid off the Pianet, the shielding on the inside of the lid reduces a LOT of noise when screwed in place.
Good luck with your project!
Hi Ben,
Thanks for your comment. My Ken Rich pads arrive next week. I ordered them after hearing the sound of their pads in the video.
The C has a different pre-amp to the N. I haven’t put a meter across it yet but I’ll definitely be careful. I’ve got a few ideas for improving the circuit and grounding, so hopefully I’ll end up with something quieter and louder.
Glad to hear you’re happy with your N.
Cheers,
Malcolm.