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Motorola VRS750 Service Manual

Vehicular repeater system
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VRS 750
Vehicular Repeater System
Detailed Service Manual
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Summary of Contents for Motorola VRS750

  • Page 1 VRS 750 Vehicular Repeater System Detailed Service Manual...

  • Page 2: Foreword

    This manual provides sufficient information to enable service shop personnel to troubleshoot and repair the VRS750 to the component level. Safety Information Before operating the VRS750, please read the “User Safety, Training, and General Information” section in the front of this manual. Manual Revisions Changes which occur after this manual is printed are described in “FMRs.”...

  • Page 3: Table Of Contents

    VHF VRS750 Performance Specifications ........
  • Page 4 VRS Mode Steering ............23 Time-Out Timer .

  • Page 5: User Safety, Training, And General Information

    STATION. Compliance with RF Energy Exposure Standards Your Motorola two-way radio is designed and tested to comply with a number of national and international standards and guidelines (listed below) regarding human exposure to radio frequency electromagnetic energy. This radio complies with the IEEE (FCC) and ICNIRP exposure limits at duty cycles of up to 50% talk-50% listen and should be used for occupational use only.
  • Page 6 • a. The requirements of the antenna manufacturer/supplier b. Instructions in the Radio Installation Manual Use only Motorola approved supplied antenna or Motorola approved replacement antenna. • Unauthorized antennas, modifications, or attachments could damage the radio and may violate FCC regulations.
  • Page 7 Vehicles To avoid possible interaction between the radio transmitter and any vehicle electronic control modules, for example, ABS, engine, or transmission controls, we recommend that the radio be installed by an experienced installer and that the following precautions be used when installing the radio: 1.

  • Page 8: Safe Handling Of Cmos Integrated-Circuit Devices

    This discharges any static charge you may have accumulated. NOTE: Wear a conductive wrist strap (Motorola part number RSX-4015A) to minimize the buildup of static charges on your person while you are servicing CMOS equipment.

  • Page 9: Model Chart For The Vrs750

    Model Chart for the VRS750 MODEL NUMBER DESCRIPTION P2080 VRS750 VHF (136-174 MHz) P2081 VRS750 UHF R1 (403-470 MHz) P2082 VRS750 UHF R2 (450-512 MHz) ITEM NUMBER DESCRIPTION X X X HHN4044* VRS750 Housing X X X HLN6855* VRS750 Mounting Assembly X X X †...

  • Page 10: Vhf Vrs750 Performance Specifications

    VHF VRS750 Performance Specifications GENERAL TRANSMITTER RECEIVER Model P2080 (136-174 MHz) RF Power Out: 275 mW to 2 W tunable Intermodulation per EIA: 70 dB † Number of Channels: 1, T1 = R1 Spurious and Harmonic Emissions: Hum and Noise: -40dBm @ 25 kHz -36 dBm <...

  • Page 11: Glossary Of Terms

    Glossary of The following glossary of terms and definitions help you to understand the VRS theory of operation. Terms Countdown A term that describes the incremental step-down function of the counter in the repeater. Approximately 500 milliseconds of time delay for conventional modes and 1500 milliseconds for trunked modes separate each successive delay state.

  • Page 12: List Of Abbreviations And Acronyms

    Portable Area Coverage Private Line Portable Priority Interrupt Portable to Base Radio Frequency Receive Serial Bus SBEP Serial Bus Expanded Protocol Time Out Timer Transmit Vehicle Interface Port Vehicular Repeater System VRS-EP Vehicular Repeater System—Expanded Protocol VRS750 Vehicular Repeater System—Model 750...

  • Page 13: Introduction

    Introduction Description The VRS750 Vehicular Repeater System is a mobile radio system component that provides on-site repeater capability between a portable radio and a base station (see Figure 1). The VRS gives the portable user the equivalent range of a mobile radio with the flexibility of a portable.

  • Page 14: Ordering Information

    The Global Tuning Tool (not included) can be used to tune the VRS output power in the field. For more information refer to “VRS750 Global Tuner,” in Chapter 2. Contact Customer Resources for information on how to obtain this...

  • Page 15: Vrs Features

    • Over-the-air interoperability with VRS-EP units. All VRS features can be programmed in the field using ASTRO Spectra mobile CPS. For more information, refer to “VRS750 Programming,” in Chapter 2. IMPORTANT NOTE: All ASTRO Spectra VRS systems with the same VRS RF transmit/receive frequency need to be CPS programmed identically to ensure proper operation.
  • Page 16 • Message (from the Control Head)—Trunking or Conventional • Status (from the Control Head)—Trunking or Conventional • Emergency Call—Trunking or Conventional—Emergency Call and VRS are mutually exclusive. Even if the mobile is programmed for Alarm and Call, when the Alarm case is exited, the mobile will not transition into Emergency Call while the VRS is activated.

  • Page 17: Installation

    VRS Installation The VRS750 is installed using the HKN6153A interface cable. The molded DB-25 end connects to the ASTRO mobile front connector. The DB-25 end with the plastic housing connects to the VRS (see Figure 2).

  • Page 18: Installation Of The Mounting Trunnion, Hln6855

    5. Connect the VRS-to-Mobile cable to the 25 pin connector on the bottom of the VRS750. 6. Position the VRS750 in the trunnion. 7. Secure the VRS750 with the two wing screws, and the split and flat washers provided. Figure 4. Securing the Trunnion Mounting Bracket...

  • Page 19: Vrs Antenna Installation

    3. Connect the antenna cable mini-UHF connector to the antenna jack on the rear of the VRS750 (see Figure 5). A mini-UHF crimp connector is provided with each VRS750 unit for easier installation with a pre-existing antenna.
  • Page 20 (see Figure 7) to select the VIP to be used. However, the VRS button must still be added to the control unit if it is desired to have the indicator light when the VRS750 is enabled. See the ASTRO Spectra CPS user’s manual for details concerning programming the VIP.
  • Page 21 Access PL Code fields will become user selectable. These fields specify the one PL frequency transmitted by the portable that will be used to access the VRS750. The VRS750 will treat that access PL in the same manner as a “select mode” mode steering PL. To edit these fields click in the Access PL Freq.
  • Page 22 Figure 8. VRS Window (Radio Configuration --> Radio Wide --> VRS) Figure 9. VRS Private Line Window (Radio Configuration --> Radio Wide --> VRS Private Line)
  • Page 23 The VRS Personality sets the VRS Frequency Band, Simplex Frequency, Channel Spacing, and TX Output Power for the VRS750. The VRS750 can be programmed for 12.5, 20, or 25 kHz Channel Spacing with a High or Low output power (factory power settings are 2 W for High and 275 mW for Low).
  • Page 24 Figure 11. VRS Personality Window (Radio Configuration --> Radio Wide --> VRS Personality) The VRS Personality can be programmed directly into the VRS750 EEPROM using Professional Radio CPS and a new dip switch configuration, Professional CPS Mode. All other operating parameters will still be programmed using the ASTRO Spectra CPS.
  • Page 25 Normal Mode (see Table 6 in Chapter 6). In order to program the VRS750 using the Global Tuner it should be connected to the mobile and to a PC via its COM port as indicated in Figure 13.
  • Page 26 We recommend setting and using a Low transmit power setting of 275 mW for optimal performance. This output power provides the VRS750 with a similar range as the portable when attached to a mobile antenna. Any deviation from this setting could result in a loss of communication from the portable to the base.
  • Page 27 Figure 14. Transmit High Power Window in the Global Tuner 5. Press PTT Toggle again to key up the radio at the selected frequency point. 6. Repeat steps 3-5 for (F2-F7). 7. Press Program to store the softpot values into the radio’s codeplug.
  • Page 28 2. Set softpot to its maximum value to mute the radio. If the VRS750 remains totally unmute at this setting, leave it at the maximum setting and continue to step 4.
  • Page 29 The VRS750 firmware can be reprogrammed/reflashed using the VRS750 Upgrade Kit. In order to use the VRS750 Upgrade Kit the VRS750 should be connected to a desktop or laptop PC via a COM port as indicated in Figure 13. The Flash adapter (NTN4056A) should be placed between the VRS750 programming cable (3085031D02) and the SRIB (see Figure 16).
  • Page 30 Figure 16. Flashing Adapter NOTE: The VRS750 Upgrade Kit will request which baud rate to use when flashing the first radio. For the VRS750 the baud rate should not exceed 38,400 bps. Contact Customer Resources for information on how to obtain this...

  • Page 31: Vrs Operation

    VRS Operation General The VRS is a crossband repeater that repeats either UHF or VHF portable transmissions though a VHF, UHF, or 800 MHz ASTRO mobile. The repeater cannot be operated with a mobile radio operating in the same band as the VRS unit. In multiple-VRS sites, the VRS uses a priority algorithm to prevent other VRS units from repeating.

  • Page 32: Vehicle Interface Ports

    the same Single Tone frequency, as well as other VRS and ASTRO mobile features. Press the VRS button to disable the VRS option. When the system is turned off and then back on from the control head, the VRS option returns to the state it was in immediately before the control head was turned off.

  • Page 33: Mobile Audio Repeat

    ICM Transmissions VRS BASE: Press the mobile’s PTT to transmit on the frequency corresponding to the mode shown on the control head’s display. If this mobile’s VRS is the priority unit (in delay state zero), the VRS unit will then become non-priority upon the mobile PTT.
  • Page 34 Notes...

  • Page 35: Operation Of Vrs Options

    Operation of VRS Options The following sections describe the operation of CPS field- programmable options of the VRS. This includes information about when to use an option and compatibility between options. Base Repeater For two-frequency simplex systems using a fixed-site repeater, you can enable the base repeater option.
  • Page 36 The portable operator sets the channel or mode select switch to the position corresponding to the desired mobile mode and keys up the portable. The VRS unit decodes the PL tone and steers the mobile radio to the desired mode. There are two types of steering supported: Transmitter Steering/Receiver Latching, and Transmitter Steering/ Receiver Steering.
  • Page 37 Steering Destination There are five types of actions, or “steering destination types,” that the VRS can be programmed to perform as a result of receiving a portable Types transmission with the specified PL: NOTE: Each receive PL can only be used once and can only be programmed with one type of steering destination (for example, a single PL cannot be programmed to both change the mobile mode and send a message.)

  • Page 38: Time-Out Timer

    • momentarily press the PTT button, • wait for the confirmation tone, and return the channel selector to a voice channel. • The VRS will not perform a portable-to-base audio repeat while the portable is transmitting on a “message request” channel. NOTE: A message cannot be generated from the control head while the VRS is activated.

  • Page 39: Vrs Mobile-Tx Acknowledgment Tones (Conventional Only)

    VRS Mobile-TX When this option is enabled, the VRS transmits a 750 Hz feedback tone after it has received a repeatable message on the portable Acknowledgment frequency. This signals the portable operator that the transmission was Tones received. If the repeated message was cut short due to the mobile TOT (Conventional Only) being exceeded or the mobile channel being changed during the repeat, a lower-pitched tone (304 Hz) sounds.
  • Page 40 Notes...

  • Page 41: Detailed Vrs Operation

    Detailed VRS Operation Multi-VRS The VRS is designed to accommodate multiple VRS units in the same area. This is accomplished by each VRS maintaining a priority level or Operation delay state. During either portable-to-base or base-to-portable transmissions, only the highest priority VRS will transmit or cause a mobile PTT.
  • Page 42 On conventional modes if the VRS <Base Repeater> option is enabled via CPS, then an additional 300 ms time delay is added to the delay states. This allows time for the mobile radios to transmit to and receive from a repeater site. Base-to-Portable When a base transmits, only the priority VRS unit will transmit to the portable.
  • Page 43 SINGLE TONE BURST UNIT A “DELAY STATE ZERO” PRIORITY UNIT MAEPF-26079-O Figure 18. Single VRS Unit Operation Two-Unit Operation The arrival of another VRS-equipped vehicle (unit B) into the coverage area of unit A has no effect on unit A’s radio operation until unit B’s VRS is enabled.
  • Page 44 TRANSMITS TO TRANSMITS TO BASE STATION AND ALL REPEATERS AND MOBILE RADIOS PORTABLE RADIOS IN AREA IN THE AREA UNIT B “DELAY STATE ZERO” PRIORITY UNIT UNIT A “DELAY STATE ONE” MAEPF-26081-O Figure 20. Two-Unit VRS Transmissions If unit B activates its VRS during portable transmissions, unit B does NOT transmit Single Tone or enable in delay state zero.
  • Page 45 TRANSMITS TO TRANSMITS TO BASE STATION AND ALL REPEATERS AND MOBILE RADIOS PORTABLE RADIOS IN AREA IN THE AREA UNIT C “DELAY STATE ZERO” PRIORITY UNIT UNIT B “DELAY STATE ONE” UNIT A “DELAY STATE TWO” MAEPF-26082 -O Figure 21. Three VRS Unit Transmission Sequence Departure of a VRS Unit The priority unit may change, depending upon the order in which they leave, as vehicles leave the coverage area.

  • Page 46: Rptr Ppi-Portable Priority Interrupt

    ~ 2 sec ~ 6 msec VRS REPEATER TRANSMITTER PORTABLE TRANSMITTER WITHOUT “PL” PORTABLE TRANSMITTER WITH “PL” MOBILE TRANSMITTER MAEPF-26083-O Figure 22. Priority Unit Reassignment Rptr PPI—Portable NOTE: When using Rptr PPI, the receiver squelch setting of the portable must be programmed for CSQ (carrier Priority Interrupt squelch).
  • Page 47 If a portable’s signal without PL tone is present when the repeater is interrupted, the repeater transmitter remains inhibited for the duration of the incoming signal. If the portable’s signal is modulated with a PL signal, the priority unit repeats the message back to the base station on top of the incoming signal.

  • Page 48: Tx Pl Self-Clearing

    TX PL is used. This feature will not operate properly unless all VRS units are programmed to transmit with the same frequency PL, and the receiver squelch of the VRS750 units is set to approximately -110 dBm.

  • Page 49: Icm Functions

    ICM Functions The in-car-monitor (ICM) allows limited use of the mobile while the VRS is enabled. <ICM Base> Mode In this mode pressing the mobile’s PTT will cause the mobile to transmit on the mode shown on the control head display. The VRS will not transmit the mic audio to the portable.

  • Page 50: Acknowledgment Tones

    • The mobile will key up and transmit mic audio to the base. 2. During a portable-to-base repeat operation, the mobile user initiates a mic PTT. • A momentary talk prohibit tone will be heard and the mic audio will be disabled. 3.
  • Page 51 • The “talk prohibit” tone (a long, low tone) indicates to the portable user that the mobile cannot access the trunking system. For portable transmissions lasting longer than one second (as opposed to a “quick-key,” which must be less than one second), the VRS will respond with one of the following tones.

  • Page 52: Non-Priority Vrs Rules

    Non-Priority VRS A priority VRS is placed into non-priority mode when one of the following occurs: Rules 1. It receives a Single Tone burst at the fixed frequency of 847.5 Hz. 2. During a base-to-portable repeat, it receives a VRS/portable frequency RF signal without proper PL during the PPI.

  • Page 53: Emergency

    3. Upon reaching delay state 0, the non-priority VRS will become the priority VRS and start repeating. The maximum delay for a non-priority VRS to countdown into priority is 3.4 seconds for conventional and 5.8 seconds for trunking. 4. If the VRS does detect another VRS system repeating within the delay state, it will stop the countdown process and stay non- priority.
  • Page 54 Emergency Feature Whether the mobile is programmed for silent or non-silent alarm is transparent to the VRS. However, the Emergency Alarm sequence Operation changes slightly between the silent and non-silent case. The main differences are listed below: 1. The alarm exit sequence For non-silent alarm, any of the following will cause the mobile to exit Emergency: •...

  • Page 55: Hardware Detailed Theory Of Operation

    Power Regulation The VRS750 is powered by the mobile’s Radio_SWB+ (13.8 VDC) at the connector P102-22. L101 and C137 are used to filter alternator whine from this signal before providing it as SWB+ to the interface board. The VRS750 utilizes the mobile’s analog (P102-2, 10, 11, 21) and digital...

  • Page 56: Audio Routing Circuitry

    Audio Routing There are four paths which are used to route audio between the mobile and the transceiver: AUX_RX_AUD, TX_AUDIO, MOB_MIC_HI and Circuitry FIL_AUD. During the three types of communications of the VRS (Portable-to-Base, Base-to-Portable, and In-Car-Monitor), the routing is as follows: Portable-to-Base On channel RF signals are received by the transceiver through the connector, W101.

  • Page 57: Single Tone Encoder

    The VRS750 Single Tone Encoder (U100-1, U124-3, U124-2, and U124- 4) is used to produce a tone which is transmitted by the transceiver when the VRS750 is activated. Other VRS750 repeaters that are on in the operating area receive this Single Tone transmission. The other...

  • Page 58: Program Sense

    Normal mode is the default and standard configuration for the VRS750. The Test Mode configuration is used when the transceiver requires tuning. The VRS750 can be put into Test Mode by placing S1 Pins 1, 2, and 3 to the OFF position before system power-up. When this setting is detected by the VRS µP at power up, the following will occur:...
  • Page 59 To exit Test Mode, power down the VRS750 and reconfigure S1 for Normal mode. The ATE Test Mode configuration is used by Motorola for testing purposes. Professional CPS Mode is available for when the user requires the transmit and receive frequencies to differ. Operation during this mode is not advised and if required please contact your Motorola sales representative for details about this mode.
  • Page 60 Notes...

  • Page 61: Maintenance And Troubleshooting

    VRS. A list of recommended test equipment is found in the “Recommended Test Equipment, Service Aids, and Tools” section of the ASTRO Spectra Basic Service Manual, Motorola publication 68P81076C20. Additional information may be found in the Troubleshooting Chart in this manual.
  • Page 62 PROG VRS—The VRS750 is in programming configuration. This is only an error if the programming cable is not plugged into the front connector of the VRS750. Reset the ASTRO Mobile radio and if the problem is not corrected check P101 Pin 9 and the PROG_SENSE line for any shorts to ground.

  • Page 63: Disassembly And Reassembly Procedures

    • Check the VRS750’s codeplug for incorrect programming. • Re-flash the VRS750 with new firmware using the VRS750 Upgrade Kit. Common Operational 1. Common Portable-to-Base Repeat Problems. Problems • Check portable for correct transmit frequency and PL. • Check portable for low battery.
  • Page 64 Front Housing Main Chassis See Detail "A" Depress Snap Here Detail "A" Figure 25. Removing the Front Housing Remove the Top Cover 1. Insert a wide flat-blade screwdriver or like instrument in the recess area on the side of the main chassis near the RF connector end (see Figure 26).
  • Page 65 Front Pry Clip Off Here Figure 27. Removing the Antenna Connector Retaining Clip 4. Retain the heat conductive insulator from under the regulator. 2) Pull board forward out of chassis 1) Push up on board through accessory connector opening Figure 28. Removing the Interface Board Transceiver Disassembly 1.
  • Page 66 VRS750 Reassembly NOTE: Replace all gaskets at each servicing to ensure proper sealing of unit. Transceiver Reassembly 1. Screw the RF adapter plug into the transceiver. Tighten until the stop on the adapter is fully seated in the RF jack.
  • Page 67 Figure 29. VRS750 Torque Sequence Table 8. VRS750 Torque Sequence Step Screw P/N Torque Notes 0310907A20 Torx T10 — Start Only — — — Place Antenna Conn. Clip 0310907A20 Torx T10 8 in-lb Number 6 Inclusive 0310907A20 Torx T10 8 in-lb...

  • Page 68: Vrs Transceiver

    3. Install the remote front housing over the 18 position connector onto the front of the chassis ensuring that both snaps are engaged. 4. Place the gasket within the recessed area for the 18-pin programming connector. 5. Connect the Programming Connector Cover to the main chassis. VRS Transceiver Field repair of the transceiver is not recommended.
  • Page 69 Mobile Communication Analyzer DC Supply Communication Analyzer ASTRO Spectra Mobile Speaker VRS750 HKN6153A Mobile Microphone W7 Control Head Figure 31. General Cabling Diagram R148 R146 R150 Figure 32. Tuning Potentiometers...
  • Page 70 b. Set the Mobile Communications Analyzer frequency to the current mobile mode. c. Switch on the Mobile Communications Analyzer RF. d. Adjust R150 on the VRS board until 3.0 kHz deviation is obtained on the VRS Communications Analyzer. e. Switch off the Mobile Communications Analyzer RF. 3.
  • Page 71 The transceiver board can be tuned using the Global Tuner when the Procedure VRS750 is in ATE Test Mode. Connect the VRS750 to the test box (RLN5394A) instead of the ASTRO Spectra mobile using the VRS750 ATE Cable (3080384N02) as shown in Figure 33. Before applying power, set dipswitch S1 pin 1 to ON and pins 2, 3, and 4 to OFF.
  • Page 72 1. Inject a -70 dBm RF Signal with Frequency F1 (for UHF)/F3 (for VHF) modulated with 1 kHz tone at 60% rated deviation (see Table 10) into the VRS750. A 1 kHz tone must be detected at the RX Audio connector on the test box to verify that the radio is receiving.
  • Page 73 C189. 1. Inject a -47 dBm RF Signal modulated with 1 kHz tone at the 60% rated deviation (see Table 10) into the VRS750. 2. Adjust the softpot value by using the slider, keying in the edit box (press ENTER to confirm selection/send a softpot value), or via...
  • Page 74 ENTER to confirm selection/send a softpot value). 3. Inject a 1 kHz at 80 mVrms signal into the external mic connector on the test box (VRS750 input). 4. Note down the deviation obtained. 5. Adjust the slider, adjust the spin control or key in softpot values (press ENTER to confirm) for the frequency point until the...
  • Page 75 6. Press PTT Toggle to dekey the radio. 7. Program the softpot value by pressing the Program button. 8. Exit the VCO Attn. 12.5 kHz function. Table 12. Deviation Specifications for VRS750 UHF/VHF Radios Band Channel Spacing (kHz) Deviation (kHz) UHF/VHF 12.5...
  • Page 76 8. Press Toggle Bias 1 in order to enable the PA Bias softpot. 9. Increase the softpot value to obtain Z until Z-Y is within the range for Bias Current as indicated in Table 13. 10. Press Toggle Bias 1 again to disable the PA Bias softpot. 11.
  • Page 77 ****** If a failure occurs, go to STEP 3 otherwise proceed 9. Press Toggle Bias again to disable the PA Bias softpot. 10. Program the Bias softpot into the radio’s codeplug via pressing Program. 11. Exit the PA Bias Low Power function. STEP 2 1.
  • Page 78 10. Press Toggle Bias again to disable the PA Bias softpot. 11. Program the Bias softpot into the radio’s codeplug via pressing Program. 12. Exit the PA Bias Low Power function. NOTE: After tuning a transceiver, go back and tune the interface board (details in this chapter) and then adjust the output power and squelch settings (see Chapter 2).

  • Page 79: Troubleshooting Charts

    Troubleshooting Charts Introduction to this This section contains detailed troubleshooting flowcharts. These charts should be used as a guide in determining problem areas. They Section are not a substitute for knowledge of circuit operation and astute troubleshooting techniques. It is advisable to refer to the related circuit descriptions in the “Hardware Detailed Theory of Operation,”...

  • Page 80: Vrs Enable Failure

    VRS ENABLE FAILURE START Is VRS Is the mobile button enabled in Program mobile codeplug for codeplug programmed the mobile VRS VIP. for VRS VIP? codeplug? the mobile Program mobile codeplug for codeplug programmed for proper VRS VIP active state. VRS VIP active state? Is switch in...

  • Page 81: Error 12/10

    ERROR 12/10 ERROR 12/84 START START Reflash the VRS750 with the correct version firmware. Is the VRS Reconnect the mobile interface cable cable. connected? Reset the system. Are the Troubleshoot the regulated voltages Is the regulator circuit. Problem is present? 12/84 error still corrected.

  • Page 82: Vrs 001, Vrs Synthesizer Lock Failure

    VRS 001 FAILURE START Does the Correct the freq. band Freq. Band field in field for the VRS750 in ASTRO CPS match the freq. Band the ASTRO mobile of the VRS750 attached to codeplug. the mobile? Replace the transceiver board.

  • Page 83: Single Tone Encode Failure

    SINGLE TONE ENCODE FAILURE START there continuity 3.3VDC square wave Replace the flex between J30-6 and at R114 during Single cable. J40-21 on the flex Tone burst? cable? Replace the transceiver. Check and/or 80mVpp sinewave replace U100, at TP104? U124. Verify that pin 10 of U101 is Is the 0VDC during the Single...

  • Page 84: Single Tone Failure

    SINGLE TONE FAILURE START Verify that the VRS750 dip switches are set to normal operation. Verify that J30-20 (boot control) is ~3.3VDC. Does TP105 pulse ~5VDC Check the mobile when the volume button to VRS cable. is pressed? Does J30-21...

  • Page 85: Base-To-Portable Repeat Failure

    BASE TO PORT. AUDIO ISSUES Verify that the VRS750 Activate the START dip switches are set to VRS750. normal operation. Provide an Is "VRS The VRS750 is not on-channel RF BOTH" displayed enabled and audio signal to the mobile. briefly? will not be heard.

  • Page 86: Portable-To-Base Repeat Failure

    PORTABLE-TO-BASE AUDIO ISSUE Verify dip switches are set to normal operation. Activate the VRS750. Is "VRS The VRS750 is not BOTH" displayed enabled and will briefly? not repeat. Provide an on channel RF signal with an Access or Mode Steering PL to the VRS750.

  • Page 87: Vrs Icm Audio Failure

    IN-CAR-MONITOR AUDIO ISSUES Verify that the VRS750 Is "VRS Activate the dip switches are set BOTH" displayed VRS750. for normal operation. briefly? During Base-to-Portable Refer to the PTT the mobile's local communications, is audio heard Base-to-Portable mic and talk into it.

  • Page 88: Serial Bus Failure

    SERIAL BUS FAILURE START Verify that the VRS750 dip switches are set to normal operation. Verify that J30-20 (boot control) is ~3.3VDC. Does TP105 pulse ~5VDC Check the mobile when the volume button to VRS cable. is pressed? Does J30-21...

  • Page 89: Portable Audio At Local Speaker Issue

    PORTABLE AUDIO AT LOCAL SPEAKER ISSUE START Verify that the VRS750 dip switch settings are set to normal operation. Activate the VRS750. Is "VRS The VRS750 is not BOTH" displayed enabled and audio briefly? will not be heard. Provide an on-channel RF...

  • Page 90: Programming/Tuning Failure

    Flashing Adapter being the VRS750. used? Plug the Cycle power to the VRS750 programming cable and try again. If the problem the mobile radio back in to the persists, try a different...
  • Page 91 Replace the Flashing Adapter 2805347X01, on the front of the header block. being used? VRS750? Is the Place the switch in the B cathode of Replace the position and reset the the switch in the B VR121 grounded when programming cable.
  • Page 92 Notes...

  • Page 93: Diagrams And Parts Lists

    Printed Circuit Board Electrical Parts List Printed Circuit Board Component Location Diagram 84-85 Printed Circuit Board Schematic Diagram 86-87 Exploded View and Exploded View Parts List VRS-to-Mobile Cable VRS-to-Siren Cable VRS750 Programming Cable VRS750 Programming Cable Schematic Diagram VRS750 Flashing Adapter Schematic Diagram...
  • Page 94 Notes...
  • Page 95 Pot, 20 k For optimum performance, order replacement diodes, transistors, C195 2113740F59 R149 0662057A91 56 k and circuit modules by Motorola part number only. C196 2113743E20 0.1 µF R150 1813905A11 Pot, 20 k When ordering crystals, specify carrier frequency, crystal frequency,...
  • Page 96 C204 TP110 U102 C104 TP102 R213 Q110 Q103 U103 R211 C202 TP114 R107 R210 R137 C122 TP112 C203 R106 C145 C138 TP120 U107 C191 R224 C189 VRS750 Vehicular Repeater System Printed Circuit Board Component Location Diagram (Sheet 1 of 2)
  • Page 97 C195 C196 C137 L101 C183 C103 C157 C133 C132 C159 C162 W102 VRS750 Vehicular Repeater System Printed Circuit Board Component Location Diagram (Sheet 2 of 2)
  • Page 98 J30 12 22.1K R172 C180 1000pF 9.6V C206 R131 TEST_MODE-IN (J40-24) 100K 220pF R156 TONES-MOBILE_AUD (J40-23) TX_RX_AUDI O (J20-14) (J40-2) (J20-15) C125 R166 4.7K 220pF TP120 TP111 TP113 VRS750 Vehicular Repeater System Printed Circuit Board Schematic Diagram (Sheet 1 of 2)
  • Page 99 R157 GND2 GND 2 GND3 GND1 Q114 C156 C157 MMBT3904 100uF C159 C162 220pF C201 R182 220pF 100uF Q106 MIC_FIL_SEL 220pF J30 15 MMBT3904 R183 C184 220pF VRS750 Vehicular Repeater System Printed Circuit Board Schematic Diagram (Sheet 2 of 2)
  • Page 100 VRS750 Vehicular Repeater System Exploded View Parts List ITEM MOTOROLA DESCRIPTION PART NUMBER 1505764X01 COVER ASSEMBLY, Midpwr Top 3205931V02 GASKET, Front Cover 1505905V02 HOUSING, Remote Front 2805347X01 CONNECTOR, 18 Position 4205395X01 RETAINER, Programming Connector 3205789W01 GASKET, Remote Cable 3385950D01 LABEL, Front...
  • Page 101 VRS-to-Mobile Cable HKN6153A VRS-to-Siren Cable HKN6154A Pin Number Pin Number ASTRO Spectra Signal Name Siren Signal Name VRS750 VRS750 Mobile DB25 (HLN1439A) P102 P102 Female 39 pin J1 FIL_Audio_GND FIL_Audio_GND Bus+ Bus+ FLT_Audio FLT_Audio Rx_Audio Rx_Audio Tx_Audio Tx_Audio AGND AGND...
  • Page 102 VRS750 Programming Cable 3085031D01 VRS750 Programming Cable 3085031D01 VRS750 Programming Cable 3085031D01 Pin Number Pin Number Signal Name Signal Name VRS750 SRIB DB25 VRS750 SRIB DB25 P101 Female P101 Female Ground Boot_Cntl Prog_Sense VRS750 Programming Cable Schematic (3085031D01) VRS750 Flashing Adapter Schematic (NTN4056A)

  • Page 103: Replacement Parts Ordering

    Send written orders to the following addresses: Replacement Parts/ Federal Government Orders: International Orders: Test Equipment/Manuals/ Crystal Service Items: Motorola Inc. Motorola Inc. Motorola Inc. United States and Canada United States and Canada United States and Canada Accessories and Aftermarket...
  • Page 104 *6881094C84* *6881094C84* Motorola 8000 West Sunrise Boulevard Fort Lauderdale, Florida 33322 68P81094C84-O...

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