Mackie CR1604-VLZ 16 ch mixer
 

More out of curiosity than necessity for repair.
I only have the user manual, block diagram, that shows reference to an 8 way
relay for SOLO LED indicators and related signal routing.
No sign of a relay - are a number of the ubiquitous 4560 dual op-amps tied
together and used as gates ?

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Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/