[Milsurplus] RT-353 circuit info?

[MWM]

RT-353 circuit info?


Would anyone have details of the circuits on the 4 plug in pcb's inside the RT-353, only I have a tone being generated all the time which goes on and off when these boards are touched. The tone, presumably a fault signal, does not seem to affect anything, rx and tx are ok, but this constant tone in the headset makes the set unusable. 


Any circuit info would be great. 


thanks. Ben G4BXD