La Trobe Univerity Serge
From what I can determine, this instrument was built in1975 for La Trobe university by Serge, to Warren Burt's specification. To quote Warren: "we had specified a very large Serge Synthesizer to be built by Serge"*1. It became the centerpiece for studio at for the La Trobe University of Melbourne, Victoria, Australia.
It uses a combination of R series PCBs, and very early second generation "1" series boards, from before the standard board numbering system was adopted.
The first panel I repaired was this sequencer module, of which there are two in the system. It consists of a R9 Negative Slew to provide a clock for the sequencer, an R16 Sequencer, and two R15 Programmers wired as a single 8 way programmer.
The Programmers were fitted with very early orange LEDs. Even under dim lighting, they were barely visible. The first LED is lit in both photos.
Note the four white/blue striped wires that run between the two programmer boards. These are what couples them into an 8 stage programmer.
The original LED wiring. They share a common resistor, and are driven directly off the Gate outputs.
Overview of the insides of the Sequencer Panel.
Post repair and upgrade. The Sequencer had a new Reset button and a new 4017 fitted. High brightness LEDs were added to the outputs of the Sequencer, with 4k7 resistors, giving them workable brightness at very low currents, thus with minimal load on the circuitry. LEDs were added to the ramp outputs of the Negative Slews. Cycle switches were added so they could be used as LFOs without needing to be patched. LEDs in the Programmer were replaced. An 8 pole switch was added to connect the first eight outputs of the sequencer to the programmer inputs, allowing a flick of the switch to couple the two together, instead of the previously required 8 patch cords. Patch cords can still be used if the switch is off.
The Sequencer panel, with new LEDs and switch.
*1. From the vicmod/blog Warren Burt interview.
Photographs copyright by Ken Stone.
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