hifi engine

Sony SQ Checker model 0005 (Test Equipment)

Hi guys,

I have just acquired the above piece of test equipment. I believe this was an item of in-house test gear. So far i have been unable to find any information on this. It would appear to be a signal generator for checking or aligning SQ quadraphonic decoders.
I'm looking for any information such as how to use it, schematic, manuals etc.