Regency MCA 611a
 

Does anybody have a service manual or schematic for these old
non-scanning monitors? I have the little yellow user manual, but it
doesn't have any real tech info. The units apparently will decode
two-tone signals, but there is no info on how to adjust the frequencies
for this. It does not take reeds, but seems to have adjustable pots.
Also, the models I have do not have a monitor/reset button, only a reset
button, so unless there is a two-tone decoding, the unit stays
squelched. And there is no external squelch control on the front of the
unit. There must be one inside, but I am hesitant to start moving pots
without a good drawing.