Motorola Cm Radio Controlheads Manual

							Controlhead Model for CM160 and CM3602-5
3.3 Keypad Keys
The control head keypad is a four-key design. All keys are configured as two analog lines read by 
µP. The voltage on the analog lines varies between 0V and 3.3 V depending on which key is 
pressed. If no key is pressed, the voltage at both lines is 3.3V. The key configuration can be thought 
of as a matrix where the two lines represent one row and one column. Each line is connected to a 
resistive divider powered by 3.3V. If a button is pressed, it will connect one specific resistor of each 
divider line to ground level and thereby reduce the voltages on the analog lines. The voltages of the 
lines are A/D converted inside the µP (ports PE 6 - 7) and specify the pressed button. To determine 
which key is pressed, the voltage of both lines must be considered.
The same analog lines also support a keypad microphone. A microphone key press is processed in 
the same manner like a control head key press.
3.4 LCD Driver
The LCD (36 x 4 segemnts) is controlled by U3. It has an on onboard clock controlled by R28 
(typically 20kHz measured on pin 2). U3 is operated from the 5V supply and is controlled over the 
SPI bus (SPI_CLK J103-17, SPI_MOSI J103-16, LCD chip select J103-18). Chip select is active low. 
U2 is used to provide level shifting between the 3.3V logic from the uP and the 5V required by U3.
3.5 Status LED’s and Back Light Circuit
All indicator LEDs (red, yellow, and green) are driven by current sources. To change the LED status 
the host radio sends a data message to the control head shift register via the SPI bus. The control 
head shift register determines the LED status from the received data and switches the LEDs on or 
off via Q8-Q10. 
Backlighting for the LCD and keys is provided by a matrix of 21 LEDs arranged in 7 columns of 3 
rows. The LEDs are driven from a constant current circuit (Q12, U1 and associated parts).  There are 
4 levels of baclight: off, low, medium and high, which are controlled by two outputs (pins 15, 1) from 
the shift register (U8). The current is controlled by transistor Q12. The op amp U1 monitors the 
current by measuring the voltage drop across R26, R27 and adjusting the bias of Q12 to achieve the 
required level as set by the combined shift register o/ps. When in the off state, Q11 is also turned on 
to clamp the base of Q12 so as to force it off. This ensures that the LEDs are fully off. Q11 is 
controlled by pin 3 of the shift register U8.
3.6 Microphone Connector Signals
The MIC_PTT line (J102-3) is grounded when the PTT button on the microphone is pressed. When 
released, this line is pulled to 9.3V by R33. Two transistor stages (Q14, Q13 and associated parts) 
are used to level shift between 9.3V and 3.3V required for the uP while keeping the same sense 
(active low for PTT pressed).
Two of the mic socket lines (J102-2, 7) have dual functions depending on which type of microphone 
or SCI lead that is connected. An electronic switch (U41) is used to switch these two lines between 
mic keypad operation or SCI operation. The switch (mux) is controlled by the uP through J103-20 
with level shifting (and inversion) provided by transistor Q41. When MUX_CTRL (103-20) is low the 
electronic switch is in the mic keypad mode. The mic socket (J102) pin 2 is connected to the keypad 
row line that goes to J103-13 and pin 7 is connected to the keypad column line that goes to 103-12. 
When MUX_CTRL (103-20) is high the electronic switch is in the SCI mode. The mic socket (J102 
pin 2) is connected to the SCI line that goes to J103-4 and pin 7 is connected to the BOOT_RES line 
that goes to J103-11. 
						

							2-6THEORY OF OPERATION
The HOOK line (J102-6) is used to inform the uP which type of microphone or SCI lead is connected 
to the microphone socket. The voltage of the HOOK line is monitored by the uP (port PE0, 
MIC_SENSE) through a resistor divider on the main board. When the HOOK line is grounded (on 
hook condition) or floating (2.8V nominal), the uP sets the mux (U8) for keypad operation to allow the 
use of microphones with a keypad. When the HOOK line is connected to 9.3V, the uP sets the mux 
for SCI operation. This mode is also used to select low cost mic operation where the gain of the 
microphone path is increased (on the main board) to compensate for not having a pre-amp in the low 
cost mic.
If the BOOT_RES (J102-7) line is connected to >5V (e.g. 9.3V) at turn-on then 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). 
3.7 Speaker
The controlhead 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 controller is fed via connector 
J103-1, 2 to the speaker connector P101 pin 1 and pin 2. The speaker is connected to the speaker 
connector P101. The controlhead speaker can be disconnected if an external speaker, connected on 
the accessory connector, is used.
3.8 Electrostatic Transient Protection
Electrostatic transient protection is provided for the sensitive components in the controlhead by 
diodes VR1 - VR4. The diodes limit any transient voltages to tolerable levels. The associated 
capacitors provide Radio Frequency Interference (RFI) protection. 
						

							Chapter 3
TROUBLESHOOTING CHARTS
1.0 Controlhead CM140/CM340 Troubleshooting Chart
1.1 Control Head Failure
Back light
OK ?Check 9.3V on 
R808, R809No
Control Head Check
Power-up
Alert Tone
OK ?Check Speaker
ConnectionNo
Power-up
Red LED
Flash ?Check 
D801, Q806, U801No
Channel
Display
OK?Check
DS801, U801, U802No
Up/Down
P1 and P2
Alert Tone
Buttons OK?
Check R845, R846
R810, R811No
EXT
PTT
OK ?
Check Q801, Q802No
Communication OkCheck Q803, Q812
Control Head is OK
YES
YES
YES
YES
YES
YES
No 
						

							3-2TROUBLESHOOTING CHARTS
1.2 Button/Tones Select Error (Page 1 of 2)
No
Check Voltage Levels on
TP401 (Keypad Col)
and TP402 (Keypad Row)
(see table on next page)
Right
Voltage
Up Key
No
Check R846, R811
on Control Head
Right
Voltage
on Down Key
?
Check Control Head
connectivity continuity 
and R429, R430, D401
(main board)
Connect DTMF Mic
to TELCO Connector
YES
Button/Tones Check
Check R845, R810
on Control Head
Right
Voltage
on P1/P2
Keys ?
Is there
0.75 Vdc on
MIC_SENSE
R429, on radio
Check R813, R814
on Control Head
?
A
YES
No
YES
No 
						

							Controlhead CM140/CM340 Troubleshooting Chart 3-3
1.3 Button/Tones Select Error (Page 2 of 2)
Key_Col
Vo l t a g e
(TP401)Key_Column Voltage TP401
0.008 V0.675 V1.346 V1.997 V2.650 V3.300 V
0.008 VUp
0.675 V 1 2 3
1.346 V  4 5 6 7
1.997 V 8 9 0 *
2.650 V # C B A
3.300 V
DownLeft Key
P1Right Key
P2Idle
Key_Row Voltage TP402
NoRight
Voltage
on DTMF keys
?
Replace
Q812
YES
Button/Tones Keys
Okay
A
Does Q812
on Control Head
operates well
?
Replace U803
on Control Head
YESNo 
						

							3-4TROUBLESHOOTING CHARTS
2.0 Controlhead CM160/CM360 Troubleshooting Chart
2.1 Control Head Failure
Back light
OK ?Check 9.3V on 
Q12, U1 and associated
parts and U8No
Control Head Check
Power-up
Alert Tone
OK ?Check Speaker
ConnectionNo
Indicator
LED’
S
OK ?
Check 
Q8-Q10, U8 and 9.3VNo
Display
OK?Check LCD
connections, U3 for 5V, 
Osc. pins 1 & 2 activity
SCI thru via U4 No
Up/Down
P1 and P2
Alert Tone
Buttons 
OK?
Check keypad resistorsNo
EXT
PTT
OK ?
Check Q13, Q802No
Communication OkCheck Q803, Q14 and 
associated parts
Control Head is OK
YES
YES
YES
YES
YES
YES
No 
						

							Controlhead CM160/CM360 Troubleshooting Chart 3-5
2.2 Button/Tones Select Error (Page 1 of 2)
No
Check Voltage Levels on
TP401 (Keypad Col)
and TP402 (Keypad Row)
(see table on next page)
Right
Voltage
Up Key?
No
Check R13, R45
on Control Head
Right
Voltage
on Down 
Key?
Check Control Head
connectivity continuity 
and R429, R430, D401
(Main Board)
Connect DTMF Mic
to TELCO Connector
YES
Button/Tones Check
Check R12, R49 
on Control Head
Right
Voltage
on P1-P4
Keys ?
Is there
0.75 Vdc on
MIC_SENSE
R429, on radio
Check R31, R29
R51, R11 
on Control Head
A
YES
No
YES
No 
						

							3-6TROUBLESHOOTING CHARTS
2.3 Button/Tones Select Error (Page 2 of 2)
Key_Col
Vo l t a g e
(TP401)Key_Column Voltage TP401
0.008 V0.675 V1.346 V1.997 V2.650 V3.300 V
0.008 VUp
0.675 V 1 2 3
1.346 V  4 5 6 7
1.997 V 8 9 0 *
2.650 V # C B A
3.300 V
DownLeft Key
P1Right Key
P2P3 P4 Idle
Key_Row Voltage TP402
NoRight
Voltage
on DTMF keys
?
Replace
Q41
YES
Button/Tones Keys
Okay
A
Does Q41
on Control Head
operates well
?
Replace U8
on Control Head
YESNo 
						

							Chapter 4
CONTROLHEAD PCB / SCHEMATICS / PARTS LISTS
1.0 Allocation of Schematics and Circuit Boards
Ta b l e 4 - 1Controlhead Diagrams and Parts Lists
PCB :
Controlhead CM140/CM340
8488998U01Main Board Top Side
8488998U01Main Board Bottom SidePage 4-3
Page 4-3
SCHEMATICS
Sheet 1 of 1
Page 4-4
Parts List
8488998U01Page 4-5
Ta b l e 4 - 2Controlhead Diagrams and Parts Lists
PCB :
Controlhead CM160/CM360
8489714U01Main Board Top Side
8489714U01Main Board Bottom SidePage 4-6
Page 4-6
SCHEMATICS
Sheet 1 of 1
Page 4-7
Parts List
8489714U01Page 4-8 
						

							4-2 CONTROLHEAD PCB / SCHEMATICS / PARTS LISTS
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