Ah, one of the budget level Fluoroscan receiver from Pioneer, only a step up from the SX-3400. The SX-3500 just has more "fluoroscan" components over the SX-3400.
Basic testing shows the fluoroscan are still pretty bright. DC offset are good, controls are being cleaned, FM sounds okay and power meter works!
Still need to put it through it paces, I haven't heard one for a very, very long time. More to come!