EFJohnson 764X, 761X service manual VHF IC PIN Descriptions, Line Description, Pin Port Description

Page 48

VHF (7610) 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 R43-R45, C60, and C61. The output of this filter is the DC control voltage applied to the VCO. The phase detector increases or decreases this control voltage to change the VCO frequency.

5.3.2 VCO CIRCUIT

The VCO signal is amplified by buffer amplifiers Q6 and Q4 and is then applied to T/R switch D5 and D6. The VCO receive injection signal is applied to first mixer Q13 via bandpass filter L23, L24, and C116-C118. Likewise, the VCO transmit signal is applied to driver Q1 via buffer amplifiers Q2 and Q3. Part of the Q6 output signal is fed back to PLL IC2 as described in the preceding section.

5.4 VHF IC PIN DESCRIPTIONS

5.4.1 VHF POWER SUPPLY

Line

Description

 

 

VCC

Unswitched input voltage to the transceiver.

 

 

HV

VCC supply voltage switched by Q25 and Q26.

 

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 IC9. The

 

circuit outputs this voltage regardless of the

 

transceiver on-off condition.

 

 

8V

Common 8V supply produced from the HV

 

supply by 8V regulator Q36.

 

 

5V

Common 5V supply produced from the VCC

 

supply by 5V regulator Q29/Q30.

 

 

R5

Receive 5V supply produced by R5 regulator

 

Q27 using the “T5C” signal from I/O expander

 

IC IC11.

 

 

T5

Transmit 5V supply controlled by T5 regulator

 

Q28 using the “T5C” signal from I/O expander

 

IC11.

 

 

5.4.2 VHF 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 IC2 (main unit) and expanders IC5,

 

 

IC11 (main unit), etc.

 

 

 

13

SI

Input port for the data signal from

 

 

EEPROM IC3, etc.

 

 

 

14

SO

Outputs data signal to EEPROM IC3, PLL

 

 

IC2 (main unit) and expanders IC5, IC11

 

 

(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

 

 

IC3 (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 (Q35 on main unit).

 

 

Low = Attenuator function on.

 

 

 

36

UNLK

Input port for PLL unlock signal from the

 

 

PLL IC2 (main unit). High = unlock.

 

 

 

37

PWON

Outputs control signal for the power

 

 

switching circuit (Q25 on main unit) and

 

 

5V regulator Q29, Q30 (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 J3 (main unit). Low = Exter-

 

 

nal PTT switch on.

 

 

 

40

DIM

Input port for the LCD backlight control

 

 

signal from external connector J3 (main

 

 

unit). Low = External dimmer switch on.

 

 

 

41

PLST

Outputs strobe signals for PLL IC2 (main

 

 

unit).

 

 

 

42

DAST

Outputs strobe signals for level controller

 

 

IC5 (main unit).

 

 

 

43

EXST

Outputs strobe signals for the I/O

 

 

expander IC11 (main unit).

 

 

 

45,

KS1,

Output ports for the key matrix.

46

KS2

 

 

 

 

47-

KR3-

Input ports for the key matrix.

50

KR10

 

 

 

 

 

November 1998

5A-5

Part No. 001-7600-001

Image 48
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 75xx Accessories AccessoryToll-Free 800 Factory ReturnsReplacement Parts Internet HomeThis page intentionally left blank VHF and 7640 UHF Mobile Specifications GeneralGeneral Information Installation and Disassembly Transceiver InstallationInstalling Mounting Bracket Installing Microphone HangerPower Cable Installation Cable InstallationPower Cable Fuses Changing 20-Ampere Power Cable FusesUsing AN External Speaker Accessory Cable InstallationTransceiver Disassembly Removing PC BoardRemove shield E 2-TONE/5-TONE Module Installation Installation ProcedureSetting 5-Tone Deviation 2 2-TONE ProgrammingInstallation and Disassembly Features OperationControls and Display Transceiver Back PanelBasic Operation Direct Selection The F1-F4 Receiving and Placing Calls TIME-OUT Timer Programmable FunctionsOption Key Programmable Functions Function Key Label Description Section NoMonitor Mode Select Output Power SelectCall Guard Tone Select Channel SelectChannel Scan Priority Channel Sampling Programming Setup Section ProgrammingProgramming Cables Programming SoftwareStarting the Program Special Keys and FunctionsMenu Flow File MenuScreen Menu Program MenuPrint Menu Model MenuSetup Menu Memory Channel Screen Description LMR ModelsParameter Description Bank Select Timer Ch AtrFrequency Rx/TxAuto Reset LockoutScan ToneKey and Display Assign Screen Description Key DescriptionKey Description Label RF Power Dtmf Autodial Screen DescriptionSelection Bank/FreeContinuous Tone Screen Description Scan Function Screen DescriptionParameter Description Stop Timer 2-Tone Code Channel Screen DescriptionResume Auto CHEXO Timer Timer Auto TxAuto 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 CircuitPower Amplifier Module VHF Transmitter CircuitMicrophone Amplifier Circuit Modulation CircuitAPC Circuit VHF PLL CircuitPLL Circuit VHF IC PIN Descriptions Line DescriptionPin Port Description VHF I/O Expander IC5 Main Unit PinVHF Port Expander IC11 Main Unit 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 UnitAdjustment Procedure Test SetupSuggested Test Equipment Equipment Grade and RangeTest Channels Test CableCOMPUTER-AIDED Tuning VHF Test FrequenciesUHF Test Frequencies VHF Adjustments VHF AdjustmentsPreliminary Setup PLL Adjustment VHF ModelsVHF Adjustments CONT’D Output Power AdjustFM Deviation Adjust Dtcs Waveform Adjust Receiver Adjustments VHF ModelsBandpass Filter Adjust 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 Schematic Diagrams and Component Layouts VHF 7610 Block DiagramMain Unit 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