I believe his radio is not a Galaxy, but this radio.The printed-circuit board type number determines exactly which "old" Saturn radio you have.
The very-oldest will have this number printed in the actual copper foil, usually towards the front from the TA7222P audio chip.
If that's where you find it, the most likely number you'll see is "EPT3600-10", followed by a single letter of the alphabet.
Like this:
Later versions are "-11" and "-12". Eventually this number appears on the front edge of the circuit board, on the component side printed in the white screen-print ink.
The "-13" version dates to the early 1990s.
The "-14" was used with the suffix letters A, B or C until the early 2000s.
The schematic is different from one circuit-board type to the next, so that number is the only way to obtain an accurate road map for your radio.
73
It's not a Galaxy. It looks like it was a short run radio that was sold in the European market, Every page I found that had anything to do with it appears to be in Spain.Like finding a wiring diagram for a car that was in production for 20 years.
Gotta know the model year.
But for this kind of radio, that circuit-board number is the only real guide.
73
I went through all my saturn manuals and did not find one that showed a PB499 board.
see if this one on cbtricks matches your radio. all of mine show a number like 360010A etc.
the only PB numbers were PB999 and PB042.
http://www.cbtricks.com/radios/galaxy_other/ssb_base/index.htm
Who made the radio?Seems hard to find info about PB499 that seems its chasis... maybe few radios on the market with that chasis, i continue my finding..