Motorola PM400 Service Manual download pdf (Page 34)

100

101

Control Head Model for CM200 2-3

If the BOOT_RES (J802-7) line is connected to >5V (e.g. 9.3V) at turn-on, the uP will start in boot

mode instead of normal operation. This mode is used to programme new firmware into the FLASH

memory (U404 mainboard).

2.6 Speaker

The head contains a speaker for the receiver audio. The receiver audio signal from the differential

audio output of the audio amplifier located on the radio’s ler is fed via connector J803-1, 2 to the

speaker connector P801 pin 1 and pin 2. The speaker is connected to the speaker connector P801.

The control head speaker must be disconnected if an external speaker, connected on the accessory

connector, is used.

2.7 Electrostatic Transient Protection

Electrostatic transient protection is provided for the sensitive components in the control head by

diodes VR801, VR802, VR803 and VR804. The diodes limit any transient voltages to tolerable

levels. The associated capacitors provide Radio Frequency Interference (RFI) protection.

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Motorola PM400 Service Manual Page 34

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