In early 2003 we released a redesigned Pro-120 controller. However - in general it's such a popular and good controller that not a huge redesign was possible! The main change is that it uses sub-miniature resistors, to give room to add alterations!

Etched in the copper of the Pro-120 Mk 2 is a number such as 30-3B-2-04, there the '04' is the Issue number of the circuit board.

The table below links to the issue numbers.

01

02

03

04

These are the features that are added:

Pro-120 2 Issue 01
Released January 2003

• Regen brake defeat: two pinstrips and headers can be adjusted to inhibit regenerative braking.
• Dual Ramp reversing on/off. The feature may be turned off by a header to engage preselect reversing. This should be done if regen braking has been defeated, but can be done in any situation as desired.
• High pedal lockout defeat: the feature may now be disengaged by a removable link.
• Dead band at zero demand speed reduced (and adjustable to zero if required). There are two main events that happen when the speed pot is turned from zero: first the appropriate direction relay activates (Relay Activation Threshold = RAT). Secondly, modulation starts (Modulation Start Threshold = MST) and voltage is fed to the motor.
  • RAT preset added: this voltage was about 400mV on early Pro-120 controllers. It is now adjustable from 0 to 100mV. Factory preset will be about 50mV.
  • MST preset added: this voltage was about 550mV on early Pro-120 controllers. It is now adjustable from approximately between -200mV and 500mV. Factory preset will be approx 150mV.
  
  Factory preset values almost completely remove the present deadband (which is not beneficial in some applications) yet should suit almost all users.

Pro-120 2 Issue 02

June 2003. Most of the changes are minor tidying up of issue 1.

• Ignition switch circuitry altered: there have for a long time been factory options on the ignition. These are now more easily accessible.
• Current limit circuitry changed to new version (which has been in use on NCC and other controllers for a time).

Pro-120 2 Issue 03

September 2003. More tidying!

• The direction relay catching diodes had been beneath the relays: this makes replacing them difficult (but they rarely fail). Now moved.
• 100R added in series with top of pot - this will make the circuit even more tolerant of wiring faults back to the pot.

Pro-120 2 Issue 04
February 2004

• Some rearranging to put the two regen defeat links next to each other. The links are now not fitted as standard to simplify production and because getting the links wrong can blow the controller.
• Ignition circuit modified. See Pro-120 Ignition. The relay coil is now wired via a diode from Battery positive.
• Components moved round to allow proper fitting of extra components for 12v version. See Pro-120 series, internal power supply.
• Spacing between relays has been increased to allow fitting of a different manufacturer's relays. Note: these new relays will not fit the earlier circuit boards.

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