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This (unofficial) page provides schematics for those great audio
products made by the Electronic Instrument Company, located originally in Brooklyn, later here in Queens, and then back to Brooklyn.
The following schematics are contained in the zip:
2080, AF-4, HF12, HF20, Hf22, HF30, HF32, HF35, HF50-60, HF61A, HF65A
HF81, HF85, HF86, HF87, HF92, HF94, HFT90, MX99, ST40, ST70, ST84, ST97
Download the Schematics