You need to move R641 to R640 for mic audio.
View attachment 124707
View attachment 124708
MI/DI (MIC Signal Input/Output or Data Audio Input)
This pin has one of the two functions listed in Table 3 by
setting jumper resistors (0 ohm) R640 and R641 on the
control unit (X57-561 B/3) (Refer to page 21).
1) MIC signal input/output
This pin is directly connected to the MIC input pin of the
transceiver, so it has the same function as the MIC input
pin. When the input is 5mV/3 kHz, DEV (600 ohms)
modulation is obtained. The MIC input is output from the
transceiver panel as it is.
2) Data audio input
The signal from this pin passes through the LPF (fc: about
10kHz), is summed with the MIC AMP output, and goes
to the modulator. Therefore, it is not preemphasized.