Author Topic: Modifying A Hohner Pianet E-Piano  (Read 176 times)

sarakisof

Modifying A Hohner Pianet E-Piano
« on: October 20, 2022, 02:19:29 PM »
Hello everyone, i recently got a Hohner Pianet M electric piano.
The Pianet M is actually the same as the Pianet T (same electromagnetic pickups , pluck reeds and mechanism) but the M was designed for home use in a veneer wooden body with legs, build in phaser, amp and speakers.

On the other hand the T is completely passive. T's pickups go straight to a mini audio output transformer, 15:1 wired backwards and then to out jack so to connect with an amp.

Pianet T diagram:


T's transformer/board:
https://reverb.com/item/50516387-hohner-pianet-t-output-transformer-pcb-clavinet-duo

M is a different story. Its pickups go to an old grey male RCA cinch, (let's call it the "grey pickups RCA plug"), this one gets inserted into a female RCA socket and from there to the circuit input (C9 10uF cap in the M's scheme).
At the amp output stage it uses a DIN stereo out (not pre out, but amp out, so you get hum and it's not appropriate for driving an amp/mixer etc.) and another DIN out for headphones.

Pianet M diagram:


I want to completely bypass the M's circuit, mod it to a T passive one, but be able to return back to M when i want to use its circuit/phaser effect and play through speakers.

I'm thinking of just getting an output transformer equivalent to T's original one and make a small board with the 2nF cap (exactly like in T) and another female RCA socket.
The "grey pickups RCA plug" will be left intact as is.
I will only add an extra female RCA socket alongside with the T's board/trafo.
So, when i want to use it like a T i will connect the "grey pickups RCA plug" into my new female RCA socket and when i want M i will plug it into its old original female RCA socket like it was before.

Am i thinking it right? Any wrong doing this?

The appropriate replacement transformer according to this topic (and clavinet.com) is the Calrad 45-703.
200K : 1K
https://ep-forum.com/smf/index.php?topic=9679.0

Trafo: https://www.onlinecomponents.com/en/calrad-electronics/45703-11139585.html

A similar topic discussed here (it helps if you have auto Google Translate):
http://forum.anafrog.com/phpBB/viewtopic.php?t=6060

Peace.
« Last Edit: October 20, 2022, 10:27:29 PM by sarakisof »