Motorola Gm Series Detailed 6864115b62 B Manual

Controller Board Audio and Signalling Circuits 1-13
may be as high as 250 Hz, which is audible to the human ear. However, the radio receiver filters out 
any audio below 300Hz, so these tones are never heard in the actual system.
Only one type of sub-audible data can be generated by U0221 (ASFIC CMP) at any one time. The 
process is as follows, using the SPI BUS, the µP programs the ASFIC CMP to set up the proper low-
speed data deviation and select the PL or DPL filters. The µP then generates a square...

1-14THEORY OF OPERATION
2.4 Receive Audio Circuits
Refer to Figure5-5 for reference for the following sections.
Figure 4-1 Receive Audio Paths
2.4.1 Squelch Detect
The radio’s RF circuits are constantly producing an output at the discriminator (IF IC). This signal 
(DISC AUDIO) is routed to the ASFIC CMP’s squelch detect circuitry input DISC (U0221-2). All of 
the squelch detect circuitry is contained within the ASFIC CMP. Therefore from a user’s point of view, 
DISC AUDIO enters the ASFIC CMP, and the...

Controller Board Audio and Signalling Circuits 1-15
2.4.2 Audio Processing and Digital Volume Control
The receiver audio signal enters the controller section from the IF IC on DISC AUDIO. The signal is 
DC coupled by R0228 and enters the ASFIC CMP via the DISC pin U0221-2.
Inside the ASFIC CMP, the signal goes through 2 paths in parallel, the audio path and the PL/DPL 
path.
The audio path has a programmable amplifier, whose setting is based on the channel bandwidth 
being received, then a LPF filter to...

1-16THEORY OF OPERATION
2.4.4 Handset Audio
Certain hand held accessories have a speaker within them which require a different voltage level 
than that provided by U0271. For those devices HANDSET AUDIO is available at controlhead 
connector J0401-7.
The received audio from the output of the ASFIC CMP’s digital volume attenuator and buffered by 
U0211-1 is also routed to U0211-3 pin 9 where it is amplified 20 dB; this is set by the 10k/100k 
combination of R0261 and R0262. This signal is routed from the...

Controller Board Audio and Signalling Circuits 1-17
2.5 RECEIVE SIGNALLING CIRCUITS
Refer to Figure 5-6 for reference for the following sections.
Figure 4-2 Receive Signalling Paths
2.5.1 Sub-audible (PL/DPL) and High Speed Data Decoder
The ASFIC CMP (U0221) is used to filter and limit all received data. The data enters the ASFIC CMP 
at input DISC (U0221-2). Inside U0221 the data is filtered according to data type (HS or LS), then it 
is limited to a 0-5V digital level. The MDC and trunking high speed...

1-18THEORY OF OPERATION
2.6 Voice Storage (optional)
The Voice Storage (VS) option can be used to store audio signals coming from the receiver or from 
the microphone. Any stored audio signal can be played back over the radio’s speaker or sent out via 
the radio’s transmitter.
The Voice Storage option can by placed on the controller section or on an additional option board 
which resides on option board connector J0551. Voice Storage IC U0301 provides all required 
functionality and is powered from 3.3...

Chapter 2
TROUBLESHOOTING CHARTS
1.0 Controller Troubleshooting  Chart 
Controller Check
Power Up 
Alert Tone
 OK?
Speaker & 
Control 
Head OK?
U0101
EXTAL= 
7.3728 MHz/ 
14.7456 
MHz? 
BUS+
activity when 
volume knob 
rotated?
MCU is OK
Not able to 
program 
RF Board ICsBefore replacing 
MCU, check SPI 
clock, SPI data, 
and RF IC select 
Replace 
Speaker / Con-
trol Head
U0221 Pin 34 = 
16.8 MHz?
Check 
FGU
Reprogram the 
correct data. & 
Check ASFIC 
and MCU
Check Control 
Head and MCU 
(U0101, U0121,...

2-2TROUBLESHOOTING CHARTS 

Chapter 3
CONTROLLER SCHEMATICS / PARTS LIST
1.0Allocation of Schematics and Circuit Boards
1.1 Controller Circuits
This Chapter shows the Schematics and the the Parts Lists for the Controller circuits. 
1.2 Voice Storage Facility
The Voice Storage is fitted on all MPT radios GM640/660/1280 and on GM380 as standard.
The schematics, component layout and parts list for these circuits are shown in this chapter. 
The Voice Storage schematic is shown in Tables below.
.
.
Table 3-1   Controller T2 Diagrams and...

3-2Controller schematics / parts list
.
.
.Table 3-4   Controller T9 Diagrams and Parts Lists
Controller T9 used on PCB :
8486172B08 VHF, 1-25W
8486140B13 VHF, 25-45W
8485670z03 UHF B1, 1-25W
8485908Z02 LB3, 25-60W
SCHEMATICS
Controller Overall
Supply Voltage
Audio
I/O
Microprocessor
Voice Storage (if fitted)
Page 3-27
Page 3-28
Page 3-29
Page 3-30
Page 3-31
Page 3-32
Parts List
Controller T9Page 3-33
Table 3-5   Controller T11 Diagrams and Parts Lists
Controller T11 used on PCB :
8486206B08 LB1, 25-60W...