LUCAS Opus Type AB3 Ignition amplifier.
Replacement Amplifier Circuit Board.

The original Opus circuit was an elegant solution to the problems of mechanical ignition points and high revving Multi-cylinder engines.
Unlike today where semiconductor components are designed specifically for car electronics the Opus engineers had to rely on the availability of small selection of electronic parts with which to design their circuit.

Some of the electronic components originally used in the OPUS amplifier will have shifted in value or even partially failed over time and therefore your OPUS amplifier is attempting to operate outside its designed limits.

The OPUS circuit uses the first pulse it ÔÇÿseesÔÇÖ when the ferrite passes the pickup to fire the coil. If the oscillator output frequency or voltage shifts the primary voltage on the Pickup will be insufficient to produce the necessary stable output when the ferrites pass the trigger point in the distributor. When this happens you get a weak and irregular spark, this problem usually appears when the engine is hot.
The OPUS amplifier did not have sufficient temperature compensation or voltage regulation for reliable operation therefore accurate ignition timing was never achieved.

In redesigning the electronics we have kept with the original approach of the Opus team but used state-of-the-art electronics. The circuit still functions in a similar manner to the way it was first designed, except now the ignition amplifier, is voltage regulated and the semiconductor oscillator is temperature compensated. When coupled with the hybrid transistors specifically designed for firing ignition coils this translates to precise timing and a powerful spark every-time.

We have completed a considerable amount of road and dynamometer testing of the REOPUS circuit in my V12 E Type over the last few months to ensure reliability and performance. To date we are more than pleased with the improvement in starting, smooth running and performance using the new REOPUS circuit board. The circuit has been tested up to 6,000 rpm on our test jig and the coil firing observed on an oscilloscope.
The coil waveforms are stable, clean and synchronised to the pickup signal.

The new REOPUS circuit is installed inside the existing Opus amplifier case, it uses the original pickup, ignition coil and existing wiring. To install;
´éÀ Remove the amplifier unit from your car.
´éÀ Remove the base plate, Remove the circuit board
´éÀ Cut the wires from the OPUS circuit as per our detailed instructions
´éÀ Fit the new cable plate and install the REOPUS circuit board.
´éÀ Solder the 6 wires onto the new REOPUS circuit as detailed in our instructions.
´éÀ Reconnect the connectors from the Pickup and the ballast unit.
´éÀ We have included 2 diagnostic LEDÔÇÖs on the REOPUS board so you can test the unit to ensure your wiring and static timing is correct before restarting the engine.
´éÀ Refit the base plate and reinstall the amplifier module into your car.

Submitted by dcurry@xtra.co.nz on Wed, 06/14/2006 - 04:44

Jeff
I have tried to send you a email reply and the email was returned.
The answer is yes we are building the circuit boards for sale. Could you forward to me your postal address or email address that I can access and I will send you price details.
Dave Curry

Submitted by jsmith@pathfire.com on Mon, 06/12/2006 - 13:17

David, read your email on the redesigned circuit board for OPUS ignition. Great description, but do you (your company) offer this service? If so, what is the price? I've got an extra OPUS unit that still works, but I would not mind getting it upgraded.
Thanks,
Jeff Smith
Atlanta, GA
74' etype OTS