MGB Opus Ignition

Later MGB cars ('77-'79) came with the Lucas Electronic Ignition distributor with integral amplifier (also known as Opus ignition) . Most of these were replaced due to poor reliability. It is possible to repair these amplifiers, but there is no guarantee of improved reliability. The part that fails is the epoxy circuit board. By using special chemicals in an area designed for this type of work, I was able to remove all the epoxy and get a glimpse inside.

The circuit is made of a simple printed circuit board. For appliations where ruggedness is important and where vibration and alternating hot and cold are encountered the PC board should have through-hole plating. This means that the parts are not only soldered on top of the board where the trace is, but also inside the hole for maximum strength. The boards for the Lucus Opus ignition are not through hole plated. This is a major shortcoming. In the amplifier I took apart, the problem was a crack in the trace at Q2 where the part is attached. The PC board inside looks something like this.