No Audio (Main Unit); Wireless Sa-Pt660; Outline Models; Mech Sa-Pt760 - Panasonic SA-PT660 Technical Manual

Audio – Speaker Output Waveforms
Units with a digital power output IC always outputs a sine wave at the speaker terminals
Normal "RF" waveform at the speaker
terminals even when there is no sound!
No Audio
Output IC is ON * but may be muted or
no audio is input.
Spk Terminal Output = background sine wave at
1.4Vp-p @ 375kHz. Duty cycle = 50%
Average spk DC voltage = 0Vdc
Same output with or without speakers.
* Output ICs can be turned off from the mute
input. 5V = norm, 3V = mute, 0V = Off.
Slide # 40
Digital Scope snapshot at the Speaker Terminals
@ spk term
Typical voice waveform
at the speaker terminals
Music or Voice Audio
There is a constant 1.4Vp-p minimum signal
with the digital (PAM) audio.
Background sine wave is modulated with
voice audio that averages above and
below the 0V center line (PAM).
PAM = Pulse Amplitude Modulation
@ spk term
Outline Models:
Wireless SA-PT660
Mech SA-PT760
Pwr Supply SA-PT960
Protection SA-PT1060
Audio SH-FX67, 85