EFJohnson 764X, 761X service manual UHF Power Supply, UHF CPU IC1 Port Allocation

Page 54

UHF (7640) CIRCUIT DESCRIPTION

The phase detector determines the phase differ- ence between these signals and then produces output pulses on pin 8 which are filtered by the loop filter.

This filter consists of Q34, R180, R181, and C202- C204. The output of this filter is the DC control volt- age applied to the VCO. The phase detector increases or decreases this control voltage to change the VCO frequency.

5.7.2 VCO CIRCUIT

Separate receive and transmit VCOs are used. The receive VCO consists of Q23/D20/D34 and the transmit VCO consists of Q25/D22/D33. The signal from these VCOs is amplified by buffer amplifiers Q28 and Q29 and is then applied to T/R switch D18 and D19. The VCO receive injection signal is applied to first mixer Q3, and the VCO transmit signal is applied to driver Q21. Part of the Q28 output signal is amplified by Q29 and fed back to PLL IC10, pin 2 as described in the preceding section.

5.7.3 UHF POWER SUPPLY

Line

Description

 

 

VCC

Unswitched input voltage to the transceiver.

 

 

HV

VCC supply voltage switched by Q14 and Q15.

 

When the [POWER] switch is pressed, the CPU

 

outputs the “PWON” control signal to this circuit

 

to turn the HV supply on.

 

 

CPU5V

Common 5V supply for the CPU produced from

 

the VCC supply by CPU5V regulator IC3. The

 

circuit outputs this voltage regardless of the

 

transceiver on-off condition.

 

 

8V

Common 8V supply produced from the HV

 

supply by 8V regulator IC2.

 

 

5V

Common 5V supply produced from the HV

 

supply by 5V regulator Q12/Q13.

 

 

R8

Receive 8V supply produced by R8 regulator

 

Q10/Q11 using the “TXC” signal from I/O

 

expander IC13.

 

 

T8

Transmit 8V supply controlled by T8 regulator

 

Q8/Q9 using the “TMUT” signal from I/O

 

expander IC13.

 

 

5.7.4 UHF CPU IC1 PORT ALLOCATION

Pin

Port

Description

No.

Name

 

 

 

 

1

VIN

Input port for overvoltage detection from

 

 

the vehicle power source.

 

 

 

12

SCK

Outputs clock signal to EEPROM IC3,

 

 

PLL IC10 (main unit) and expanders

 

 

IC12, IC13 (main unit), etc.

 

 

 

13

SI

Input port for the data signal from

 

 

EEPROM IC3, etc.

 

 

 

14

SO

Outputs data signal to EEPROM IC3, PLL

 

 

IC10 (main unit) and expanders IC12,

 

 

IC13 (main unit).

 

 

 

16

CLIN

Input port for cloning signal.

 

 

 

17

CLOUT

Output port for cloning signal.

 

 

 

18

POSW

Input for the POWER switch. Low =

 

 

POWER switch pushed.

 

 

 

19

NOIS

NOIS signal input port from the FM IF

 

 

IC1 (main unit) for noise squelch

 

 

operation.

 

 

 

26

PTT

Input port for the PTT switch. Low = PTT

 

 

switch pushed.

 

 

 

32

RFATT

Outputs RF attenuator control signal to the

 

 

attenuator switch (Q1 on main unit).

 

 

Low = Attenuator function on.

 

 

 

36

UNLK

Input port for PLL unlock signal from the

 

 

PLL IC10 (main unit). High = unlock.

 

 

 

37

PWON

Outputs control signal for the power

 

 

switching circuit (Q14/Q15 on main unit).

 

 

 

38

DIM

Outputs control signal for LCD backlight.

 

 

Low = LCD backlight on.

 

 

 

39

EXTPTT

Input port for the PTT switch from exter-

 

 

nal connector J5 (main unit). Low =

 

 

External PTT switch on.

 

 

 

40

DIM

Input port for the LCD backlight control

 

 

signal from external connector J5 (main

 

 

unit). Low = External dimmer switch on.

 

 

 

41

PLST

Outputs strobe signals for PLL IC10 (main

 

 

unit).

 

 

 

42

DAST

Outputs strobe signals for level controller

 

 

IC12 (main unit).

 

 

 

43

EXST

Outputs strobe signals for the I/O

 

 

expander IC13 (main unit).

 

 

 

45,

KS1,

Output ports for the key matrix.

46

KS2

 

 

 

 

47-

KR3-

Input ports for the key matrix

50

KR10

 

 

 

 

 

November 1998

5B-11

Part No. 001-7600-001

Image 54
Contents 761x VHF 764x UHF Conventional Mobile Conventional FM TWO-WAY Radio Table of Contents Table of Contents CONT’D Schematic Diagrams and Component Layouts General Information Toll-Free 800 75xx AccessoriesAccessory Factory ReturnsReplacement Parts Internet HomeThis page intentionally left blank VHF and 7640 UHF Mobile Specifications GeneralGeneral Information Installation and Disassembly Transceiver InstallationPower Cable Installation Installing Mounting BracketInstalling Microphone Hanger Cable InstallationUsing AN External Speaker Power Cable FusesChanging 20-Ampere Power Cable Fuses Accessory Cable InstallationTransceiver Disassembly Removing PC BoardRemove shield E Setting 5-Tone Deviation 2-TONE/5-TONE Module InstallationInstallation Procedure 2 2-TONE ProgrammingInstallation and Disassembly Features OperationControls and Display Transceiver Back PanelBasic Operation Direct Selection The F1-F4 Receiving and Placing Calls Option Key Programmable Functions TIME-OUT TimerProgrammable Functions Function Key Label Description Section NoCall Guard Tone Select Monitor Mode SelectOutput Power Select Channel SelectChannel Scan Priority Channel Sampling Programming Cables Programming SetupSection Programming Programming SoftwareMenu Flow Starting the ProgramSpecial Keys and Functions File MenuPrint Menu Screen MenuProgram Menu Model MenuSetup Menu Memory Channel Screen Description LMR ModelsParameter Description Bank Select Frequency TimerCh Atr Rx/TxScan Auto ResetLockout ToneKey and Display Assign Screen Description Key DescriptionKey Description Label Selection RF PowerDtmf Autodial Screen Description Bank/FreeContinuous Tone Screen Description Scan Function Screen DescriptionParameter Description Resume Stop Timer2-Tone Code Channel Screen Description Auto CHAuto Tx EXO TimerTimer Auto Tx StunCommon Screen Description Expert Screen Description Unique PMR European Screens Unique PMR ScreensCloning Programming ONE Transceiver with Another Memory Channel Screen PMR Models This page intentionally left blank VHF 7610 Circuit Description VHF Receiver CircuitAudio Amplifier Circuit Receiver Mute CircuitMicrophone Amplifier Circuit Power Amplifier ModuleVHF Transmitter Circuit Modulation CircuitAPC Circuit VHF PLL CircuitPLL Circuit VHF IC PIN Descriptions Line DescriptionPin Port Description VHF Port Expander IC11 Main Unit VHF I/O Expander IC5 Main UnitPin Pin Port Description NameUHF 7640 Circuit Description UHF Receiver CircuitSecond if System IC1 UHF UHF Transmitter Circuit PLL Circuit UHF UHF PLL CircuitUHF Power Supply UHF CPU IC1 Port AllocationUHF I/O Expander IC12 Main Unit UHF Port Expander IC13 Main UnitSuggested Test Equipment Adjustment ProcedureTest Setup Equipment Grade and RangeTest Channels Test CableCOMPUTER-AIDED Tuning VHF Test FrequenciesUHF Test Frequencies Preliminary Setup VHF AdjustmentsVHF Adjustments PLL Adjustment VHF ModelsVHF Adjustments CONT’D Output Power AdjustFM Deviation Adjust Bandpass Filter Adjust Dtcs Waveform AdjustReceiver Adjustments VHF Models Squelch AdjustBeep Tone Level Adjustment Beep Tone LevelUHF Adjustments PLL Adjustment UHF ModelsTransmitter Adjustments UHF Models UHF Adjustments CONT’D UHF Adjustment PointsUHF Adjustments CONT’D Receiver Adjustments UHF Models Parts List Æçìíýõ9+ôý0$,1ý81,7Íäç HUDPLFý&ìçíåý-%ýì+ýìíë.ð7ð$ Íëëðêäíçðíçí Íäæ Ìää HUDPLFý&ìçíåý-%ýì&ýìíé.7ð1 Íëëðêäíçðçìé Ëíí Ëäí HUDPLFý&ìçíåý-%ýìýìíê.ð7ð$ Íëëðêäíçðíçê Ëäì RLOý0/ìçíå$ýì5í.ð7 Íëëðêäíçðçèç 03ì Ýìäëëý9&2ýFDVH 5íéé 5HVý5-ê*-ýìííý9ýõìíýRKPô Íëëðêäíçðìêå 5íéè 5ìèé 5HVý5-ê*-ýìíéý9ýõìííýNýRKPô Æçéíýõ8+ôý0$,1ý81,7 Íêì HUDPLFý&ìçíåý-%ýì+ýìíë.ð7ð$ Íëëðêäíçðíçí Íêë Íäé HUDPLFý+0çí6-ý&+ýíêíýèíí9ý Õéäíðèìëý0+ô Ìèì 5HIý1Rï Êëç Íëëðêäíçðäèë 4éì 7UDQVLVWRUý7&êçê.ý7ìéæ 5íæé 5ìçå 5HVý5-ê*-ýìíéý9ýõìííýNýRKPô 5217ý81,7 Õ9+ý$1ý8+ý02/6ô =HQHUý0$åíèìð0ýõ7ô Æçìíýõ9+ôý&+$66,6ý3$576 VHF 7610 Exploded View Front UnitUHF 7640 Exploded View Main Unit Schematic Diagrams and Component LayoutsVHF 7610 Block Diagram Front UnitVHF 7610 Transistor Basing Diagrams Foldout → VHF 7610 Main Board TOP View VHF 7610 Main Board Schematic VHF Main UnitUHF 7640 Block Diagram UHF 7640 Main Board Bottom View UHF 7640 Main Board TOP View J4 T o O p tion al Un itUHF 7640 Main Board Schematic VHF/UHF Front Unit Board TOP View VHF/UHF Front Unit Board Bottom ViewVHF/UHF Front Unit Schematic UHF 7640 Transistor Basing Diagrams