“Here are the L100 series and Porta-B modifications in including the very large article discussing the modifications in great detail and the various schematics. The schematics include the stock schematics as well as the modified schematics so that you can easily compare the differences between the stock circuits and the modified circuits.
The article is now up to date however there is one section which mentions the potential possibility of being able to slow down the vibrato/chorus speed rate so that it would be at a similar speed as the slow Leslie speed, but I have not yet actually tried this out so therefore that section is inconclusive.
There are a few differences in the Vibrato amplifier circuit of the earlier L100 series organs and the later L100 series organs so therefore the appropriate schematics will be needed. The L-series service manual includes the schematics of the different versions of the L100 series circuits.”
WARNING AND DISCLAIMER:
There are dangerous and potentially lethal high voltages inside the L100 series organs and the Porta-B organs including the AC wiring panel of the Tone Wheel Generator, the TG synchronous motor and it’s associated starting capacitor, the Power amplifier, the Preamplifier / Percussion amplifier module, the Vibrato amplifier module, the organ Off/On switch, and in some of the various wires that are inside the organ.
As well as that, the power supply filter electrolytic capacitors inside the Power amplifier, the Percussion amplifier module and the Vibrato amplifier module can store lethal high DC voltages for an unspecified amount of time after the organ has been switched off and the mains AC plug disconnected from the mains line AC so therefore in order to allow the stored charge to safely drain away from the power supply electrolytic capacitors, it is necessary to leave the organ switched off for at least 24 to 48 hours before attempting any of the modifications that involve the Power amplifier, the Percussion amplifier module or the Vibrato amplifier module.
If you are electrically competent to do so then you can safely discharge all of the power supply filter electrolytic capacitors so that any potentially lethal stored charge is removed before you attempt any of the modifications that involve the Power amplifier, the Preamplifier / Percussion amplifier module or the Vibrato amplifier module.
With this in mind you must proceed with caution and to observe the proper safety precautions if you decide to try out any of the modifications discussed in this article.
If you are not electrically competent to do these modifications then you will need to get a proper qualified technician or someone else who is electrically competent to do any of these modifications.
To attempt any of these modifications is to do so at your own risk and I do not accept any responsibility or liability if you damage the organ or you injure yourself in any way.