I wish! I'm currently repairing an 800 and manually tracing the circuit. R20 is the output balance adjustment. @APBT , is there anything specific you're looking for?
Hello everyone. I'm hoping for some help. I have an old Unitrol 800 series siren that has 2 blown SP3099 power output transistors. They are a TO-3 style matched pair located on the bottom of the unit. Does anyone know of equivalent replacements for these transistors? I can't seem to find them...
Shues, that's a very helpful post. Thank you. I spent a lot of time in the past week or so looking for actuals as well as substitutions for that rare matched pair. But my very early, low serial number 800 uses 2N1554 (date code from 1974) rather than SP3099.
Still plugging away at it in between my other projects,