Mikado posted:GRJ,
I do not believe they are compatible (RS 3.0 power boards and any audio board versions beyond RS 3.0). The older RS 3.0 Power boards do not generate the 5V on pins 5 and 6 as the 691RSPRA00 Universal sound power board does, hence RS 4.0 and beyond does not work.
Besides, space is the real premium inside a loco, why would you want to try to stuff something so large into a loco? If you had to have RS 3.0 sounds just take the PIC and ROM from the RS 3.0 audio board and drop them into a RS 4.0 audio board coupled with the 691RSPRA00 power board!
Mike
So with something said earlier, RS 3.0 is known to be different slightly. We know the PIC and ROM use 5V likely generated by the RS3.0 power board, however not on pins 5 and 6. Does someone have an updated diagram pinout specific to RS3.0?? Just wondering what voltages are present (maybe 8V or 9V for audio amp?) and what pins are 5V. Just trying to complete my little book of knowledge for troubleshooting and repair or mod purposes. Also potentially produce modern repair PCBs as replacements become exhausted. Again, it has been noted and understood RS3.0 is unique. You can put RS3.0 PIC and ROM into other RS versions- they all are 5V "systems".
