PRO-120 Mark 1

Internal Power Supply and Protection Circuitry

The Pro-120 and Scoota series controllers have some sophisticated internal power supply circuitry which includes reverse polarity protection, pot fault detection and high pedal lockout. This is a description of the features and of some Read More

Pro-120 Mk1 History

This page refers to the very early Mark 1 Pro-120 which is now too old for factory repair. Warning: this listing was originally generated for 4QD internal use only, so is not as fully detailed Read More

Pro-120 Key Components

The Pro-120 series are card controllers, open to the elements – and users. They are similar to the VTX and older NCC series – but have several more sophisticated protection mechanisms built in. This page Read More

Earth Fuses: Why Do They Blow?

This page deals specifically with the Pro-120, but other controllers have a fuse in the earth, or can blow a pot earth connection. This page explains how. Wiring faults can cause the fuse in the Read More

Modifying the Pro-120 for other voltages

All controllers made by 4QD are generally wide voltage operating range: limits are the operating voltages on the MOSFETs and the relays, and the power dissipation in the current source transistor used for the internal Read More

PRO-120 Ramp Reduction

The Pro-120 series acceleration and deceleration ramps are adjustable down to as fast as about 330mS. It is possible to reduce this timing but any modifications should be done with extreme caution. The ramps are Read More

Fitting Expansion Connector

Pro-120, VTX and NCC series controllers. Retro-fitting expansion connector Contents, this page Introduction Mark 1 / Mark 2 mixes VTX Pro-120 NCC Double Heading Tacho feedback board Solder Side All Controllers Additional controllers Older issues Read More

Pro-120 Robot Wars Version

The Pro is available in two versions, the standard version and the -RW version. This page explains the differences. Input decoupling There is, on the input to the standard controller, a noise decoupling circuit – Read More

Pro-120 Ignition Options

The Power relay drive circuit on the Pro-120 can be factory configured in three different ways. This page explains them. The power relay is switched on and off by a transistor that detects the internal Read More

Battery Discharge Protection: PRO-120

The Pro-120 is fitted with under voltage cutback a.k.a. battery discharge protection which turns the controller off if the battery voltage falls too low. This operates at around 20v measured inside the controller. This means Read More

Pro 120 Mark 1 Speed Controller

Professional 120 Mark 1 4 Quadrant 12v, 24v, 36v & 48v Vehicle Controller This page is for reference only. This page describes the early Pro-120. It was upgraded in 2003 to become the Mark 2 Pro-120. Read More