Introduction:

I really like the Colas livery on Class 60 locos, so treated myself to a resprayed unit from Olivia's Trains in Sheffield as an early Christmas present :-) .  Paul's Class 60 Protodrive sound project may well be refined during the life of the loco, so I've decided to fit a plugable 21 pin MX644D, via an ESU 21 pin adapter PCB, to simplify any future sound project upgrades. As a Hornby DCC ready loco, the lighting assemblies use a common negative supply, so the usual array of PNP transistor invertors are fitted on the rear of the cab bulkheads at each end. The hardware circuit is identical to the earlier MX645 equipped loco, except that as FO7 is a low current logic output on the 21 pin MX644D, I need to add an N-channel MOSFET buffer to make this output behave as a normal FO. The lighting is a similar comprehensive fit to that developed on the previous Zimo equipped DB Schenker Class 60.

This time I have completely removed the original Hornby main PCB assembly, to ensure adequate head height for the plug-in decoder and to accommodate 4000uF of stay alive capacitors.

The wiring needs a bit of planning.

All connections are soldered to the underside pads

Driver added in No.2 end cab.

Note outer marker LEDs painted with water colour yellow.

White painted cab roof with white LED Cab light fitted.

Removing the main PCB assembly from the chassis block, makes the motor flywheels and some of the drive shaft parts vulnerable to contact with the wiring. Thin plasticard sheets are therefore fitted to provide additional protection.

Overall view of the upper body shell and chassis assemblies.

Showing the three PNP transistor stages on the rear of the number one end cab.

Also, part of the 40mm x 20mm ESU 50334 speaker.

The 21 pin adapter PCB and supporting tag strip assembly, both bonded in place using Glue 'n Glaze.

Four 1000uF 25 Volt capacitors connected in parallel to provide 4000uF of stay alive capacitance.

Motor connector (male) and wheel contacts connector (female) on the chassis assembly.

A big plus point for Paul Chetter's "Protodrive" sound projects is that the driving arrangements can be as simple or as advanced as the user wishes to make them.

The previous protodrive Class 60 is programmed for full notch control, which enables the user to adjust the power settings of the diesel sounds quite independently of the locomotive speed. This is particularly useful when pulling maximum load trains, as the engine can be run up to full power before the heavy train starts to move.  However, it does require additional work on the part of the driver (or the PC schedules) to maintain the engine power at an appropriate setting as the train progresses around a layout.

I'm currently trying a more automated arrangement on the Colas 60, which allows me to select full power for the initial start, but can be returned to speed related power at the touch of a button. (With the usual Zimo sound power modification facilities active) including of course the coast button, to force the engine into idle at appropriate times.

A light engine key is also provided.... very useful, to enable acceleration and deceleration delays set via CV3 and CV4 to be reduced proportionally at the touch of a key, when operating with no train on the hook, although, as I like the feel of plenty of momentum, even in a light engine, I've made the change somewhat less than Paul's original setting.

I'm going to run with the semi-automated approach, which apart from the issue described immediately above, use Paul's original settings. These work well for me now thanks to Paul kindly shifting the speed thresholds between notch sounds up a little compared to the original.  (This remains about the only characteristic in the Zimo settings that the user cannot adjust!)   So thanks Paul!   An excellent job!