If ever there was a service manual printed for this radio, I have not heard of it.
Would be nice.
The main circuit board in that radio is the latest (more or less) version of the RCI-made "3600" series. Oldest version dates back to the 1980s.
The "15" tells us that it was designed for MOSFET final/driver transistors, not just adapted from the old design. And the speaker-amplifier chip is a 5-pin TDA2003 chip, not the 10-pin TA7222P they used for decades.
Just one problem. The only radio data I can find on line with this circuit board is the Connex 4400. It's an AM/FM-only model, and has blank space where all the SSB components would go. Not too helpful.
But that's the closest I came at CB Tricks. Looked at Ranger's download site
http://www.rangerusa.com/downloads.html
But no joy there.
That model is pretty unique. The two 4008 chips that normally select the band on that circuit board are missing. The channel selector/display board has a computer chip to take the place of the old diode-switching band select circuit. Should be more reliable.
Should be.
But I have never seen that setup in any other model, so be nice to it. I prefer the old-style selector that takes 40 clicks to go around one turn of the knob. Computer-operated channel selector/display radios use a rotary encoder that feeds up and down commands to the chip. They just don't have the same feel.
Hadn't realized that our library had such a big hole in it as this. There haven't been a lot of SSB radios sold with the "15C" main board, but we don't service data for any of them on file.
Darn!
73