B737 Acp degraded mode

[Pin Head]

Hi

Comms wise, when would you go into degraded mode (ALT) on your ACP panel.

Thanks

[Avenger]

If the remote electronics unit or ACP malfunctions, the ACP cannot control the remote electronics unit. Audio system operation can be switched to a degraded mode by placing the ALT–NORM switch to ALT. In this mode, the ACP at that station is inoperative and the crew member can only communicate on one radio.
The ACP transmitter selectors are not functional.
The transmitter selector for the usable radio illuminates when a station is operating in the degraded mode. The receiver switches are not functional, and only the usable radio is heard at a preset volume, through the headset. The speaker and speaker switch are not functional at that station. In addition, the flight interphone and service interphone cannot be used. The control wheel PTT switch INT position and the ACP PTT switch I/C position are not functional since the flight interphone is not functional.

[Pin Head]

What does the remote electronics unit do?