Mellotron m400 emy restoration

The story of the Mellotron explained: https://en.wikipedia.org/wiki/Mellotron#:~:text=The%20concept%20of%20the%20Mellotron,tape%20heads%20for%20future%20Chamberlins.

There are very few m300/400 left in the world. I was fortunate to be given one as a present, faulty and in a very poor condition, many tried to repaired it but have failed.According to its s/n it is nymber 56/100 made by EMI.

So, it was a challenge for me to restore it in full functionality.

I did my research and based on this article below mine was one of the 100 made by EMI worldwide:

 List of models[edit]

·        Mk I (1963) – double manual (35 notes on each). Very similar to the Chamberlin Music Master 600. About 10 were made.[19]

·        Mk II (1964) – double manual. 18 sounds on each manual. Organ-style cabinet, two 12-inch internal speakers and amp. Weight 160 kg.[12] About 160 were made.[19]

·        FX console (1965) – double manual with sound effects. Designed to be quieter than the Mk II, with a different DC motor and a solid-state power amplifier.[8]

·        M300 (1968) – 52-note single manual, some with pitch wheel-control, and some without. About 60 were made.[19]

·        M400 (1970) – 35-note single manual. The most common and portable model. About 1,800 units were made. It has three different sounds per frame.[12]

·        EMI M400 (1970) – a special version of the M400 manufactured by EMI music company in Britain under licence from Mellotronics. 100 of this model were made.[8]

So, I started the painful reverse engineering of this instrument without any schematics.

The biggest challenge for me was to repair and modify the motor controller board. I also had to recap the preamplification state. Service the motor ,align the sound heads and demagnetise them and adjust the pinch rollers .