As removed from a classic Pioneer Cassette Deck Model: CT-506
This Dolby processing sub-board has been tested - functioning fine
Offered as spare parts for that model or possibly other Pioneer or non-Pioneer equipment
Pioneer Dolby Processor Board (Single Channel)
Discrete semiconductors plus the PA4005 integrated circuit
Single Channel (two boards are required for a typical 2 channel machine)
Pioneer Part number: GCMK-77X
Vertical mounting from the mainboard via 10 heavy duty soldered pins
Perfect for servicing where Dolby is not working on one or both channels (two boards required in this case) and it could be easier to "drop in" one of these replacement boards instead of component level diagnosis and repair.