I've been asked to repair the central locking controller on an early Rover
SD1.

Bit of history. That car was pretty early in the UK in having electric
central locking. It uses solenoids, rather than motors which are the norm
today. Later SD1 changed to motors.

The solenoid units ain't Lucas. Not quite sure who makes them.

The control unit is pure Lucas, and very odd.

What the control unit does is provide a pulse about a couple of seconds
long to operate the solenoids, then back to zero. Even when the switch is
still made. Same as all, really.

The Lucas one uses two massive Lucas starter motor relays with 1/4" screw
termimals - rated at about 300 amps. And massive caps and a resistor box
to time them. The fuse for the entire circuit 20 amps.

I realise the early 70s was a bit early for electronic timers (although
the car has points-less electronic ignition) - but why not use the smaller
and cheaper horn type relays rated at 30 amps? They have been around since
the 50s and likely earlier.

It's not a problem repairing the thing as all bits easily available. Just
curious about the design.

--
*We never really grow*up, we only learn how to act in public.

Dave Plowman London SW
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